Topic: Muscle Physiology; Subtopic: Rigor Mortis
Keyword Definitions:
Rigor mortis: Stiffening of muscles after death due to lack of ATP and permanent cross-bridge formation between actin and myosin.
Myosin head: Part of the thick filament that forms a cross-bridge with actin to cause contraction.
ATP: Energy molecule required for detachment of myosin heads from actin during muscle relaxation.
Actin: Thin filament in muscle fibers that interacts with myosin for contraction.
Contraction: Shortening of muscle fibers due to actin-myosin interaction and ATP hydrolysis.
Lead Question - 2024 (Jhajjhar)
Given below are two statements: One is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): After death, the body muscles get stiff as a state of partial contraction of muscles.
Reason (R): Attachment of myosin head to unexpected sites on actin can take place partially.
In the light of the above statements, choose the correct answer from the options given below:
1. Both (A) and (R) are True and (R) is the correct explanation of (A)
2. Both (A) and (R) are True but (R) is not the correct explanation of (A)
3. (A) is True but (R) is False.
4. (A) is False but (R) is True.
Explanation (Answer: 3. (A) is True but (R) is False): After death, due to the absence of ATP, actin and myosin remain firmly bound, causing rigidity known as rigor mortis. This stiffness begins within a few hours post-mortem and gradually disappears as tissue decomposition starts. The myosin head does not attach to “unexpected sites” but remains fixed to actin, leading to contraction and stiffness.
Guessed Questions:
1. Which molecule is essential for detachment of myosin heads from actin after muscle contraction?
A. ADP
B. ATP
C. Calcium ion
D. Phosphate ion
Explanation: ATP is required for the detachment of myosin heads from actin during relaxation. In its absence, actin-myosin bridges remain locked, leading to stiffness, as seen in rigor mortis. ATP binds to the myosin head, allowing detachment and re-cocking of the cross-bridge during the contraction cycle.
2. Which enzyme catalyzes the hydrolysis of ATP during muscle contraction?
A. Actinase
B. Myosin ATPase
C. Creatine kinase
D. Lactate dehydrogenase
Explanation: Myosin ATPase enzyme hydrolyzes ATP to ADP and inorganic phosphate, releasing energy that powers the sliding of actin over myosin filaments. This enzyme activity is crucial for contraction and is absent after death, contributing to rigor mortis in muscle fibers.
3. Which phase marks the disappearance of rigor mortis?
A. Immediately after death
B. After tissue decomposition
C. Before ATP depletion
D. During anaerobic glycolysis
Explanation: Rigor mortis disappears after tissue decomposition due to enzymatic breakdown of actin and myosin proteins. Initially, lack of ATP causes stiffness, but as decomposition progresses, muscle proteins degrade, leading to relaxation of the body after 24–48 hours post-mortem.
4. Which ion regulates the binding of myosin to actin during contraction?
A. Sodium
B. Calcium
C. Potassium
D. Chloride
Explanation: Calcium ions play a regulatory role in muscle contraction. They bind to troponin, causing a conformational change that exposes binding sites on actin for myosin attachment. After death, calcium leakage and ATP depletion together cause sustained contraction and muscle stiffness.
5. Which structure stores calcium ions in skeletal muscle cells?
A. Sarcolemma
B. Sarcoplasmic reticulum
C. Myofibril
D. T-tubule
Explanation: The sarcoplasmic reticulum (SR) serves as a calcium ion reservoir in muscle fibers. Upon stimulation, SR releases Ca2+ to initiate contraction. After death, Ca2+ leaks continuously into the cytoplasm, causing prolonged contraction and the development of rigor mortis.
6. Which of the following best explains why muscles relax after ATP is resynthesized?
A. Myosin heads detach from actin
B. Calcium binds troponin
C. ADP accumulates in cytoplasm
D. Sarcoplasmic reticulum releases ions
Explanation: Muscle relaxation occurs when ATP binds to myosin heads, leading to their detachment from actin filaments. ATP-driven reuptake of Ca2+ into the sarcoplasmic reticulum also stops contraction, restoring resting muscle length and preventing continuous stiffness.
7. Assertion-Reason Type:
Assertion (A): Calcium ion release triggers actin-myosin cross-bridge formation.
Reason (R): Troponin binds calcium ions and exposes myosin-binding sites on actin.
1. Both (A) and (R) are True and (R) is the correct explanation of (A)
2. Both (A) and (R) are True but (R) is not the correct explanation of (A)
3. (A) is True but (R) is False
4. (A) is False but (R) is True
Explanation: Both statements are true, and (R) correctly explains (A). Calcium ions released from the sarcoplasmic reticulum bind to troponin, causing tropomyosin to shift and expose myosin-binding sites on actin, allowing cross-bridge formation and contraction initiation.
8. Matching Type: Match the following muscle types with their properties:
A. Skeletal muscle – I. Involuntary and striated
B. Cardiac muscle – II. Voluntary and striated
C. Smooth muscle – III. Involuntary and non-striated
1. A-II, B-I, C-III
2. A-I, B-II, C-III
3. A-III, B-II, C-I
4. A-II, B-III, C-I
Explanation: The correct match is A-II, B-I, C-III. Skeletal muscles are voluntary and striated; cardiac muscles are involuntary but striated; smooth muscles are involuntary and non-striated. Each type performs specific roles in movement, heart contraction, and internal organ functioning.
9. Fill in the Blanks: The neurotransmitter responsible for stimulating skeletal muscle contraction is ________.
A. Serotonin
B. Dopamine
C. Acetylcholine
D. Adrenaline
Explanation: Acetylcholine is released at the neuromuscular junction from motor neuron terminals. It binds to receptors on the sarcolemma, triggering depolarization and initiating contraction. After death, neurotransmitter activity stops, but intracellular events like ATP depletion continue causing rigor mortis.
10. Choose the Correct Statements (Statement I & II):
Statement I: Myofibrils are composed of repeating units called sarcomeres.
Statement II: Sarcomeres shorten during contraction, leading to overall muscle shortening.
1. Both I and II are True
2. Both I and II are False
3. I is True but II is False
4. I is False but II is True
Explanation: Both statements are true. Myofibrils consist of repeating sarcomeres, the functional units of contraction. During muscle contraction, actin and myosin filaments slide past each other, shortening sarcomeres and thus contracting the entire muscle fiber effectively.
Topic: Skeletal System; Subtopic: Ribs and Pectoral Girdle
Keyword Definitions:
Ribs: Curved bones forming the chest wall, protecting thoracic organs.
Vertebrochondral Ribs: The 8th, 9th, and 10th ribs attached indirectly to the sternum via cartilage of the 7th rib.
Floating Ribs: The 11th and 12th ribs, which are not attached anteriorly to the sternum.
Scapula: Flat triangular bone forming the back part of the pectoral girdle.
Coxal Bone: Hip bone formed by fusion of ilium, ischium, and pubis.
Lead Question - 2024 (Jhajjar)
Match List-I with List-II
List-I List-II
A. Vertebrochondral Ribs I. IIum, Ischium, Pubis
B. Floating Ribs II.
C. Scapula III. Acromion
D. Coxal Bone IV.
1. A-I, B-III, C-II, D-IV
2. A-III, B-IV, C-II, D-I
3. A-II, B-IV, C-III, D-I
4. A-I, B-IV, C-II, D-III
Explanation: The correct answer is Option 4 (A-I, B-IV, C-II, D-III). Vertebrochondral ribs (8th–10th) connect indirectly to the sternum via cartilage of the 7th rib. Floating ribs (11th–12th) remain unattached anteriorly. The scapula possesses the acromion process, which articulates with the clavicle. The coxal bone comprises the ilium, ischium, and pubis fused to form the hip girdle, aiding locomotion and stability.
1. The total number of ribs in the human body is:
1. 10 pairs
2. 11 pairs
3. 12 pairs
4. 13 pairs
Explanation: Humans have 12 pairs of ribs, making a total of 24 ribs. The first seven pairs are true ribs directly attached to the sternum. The next three pairs (8th–10th) are false ribs connected indirectly via costal cartilage, while the last two pairs (11th and 12th) are floating ribs not connected anteriorly.
2. The floating ribs are connected to:
1. Sternum
2. Costal cartilage
3. Vertebral column only
4. Clavicle
Explanation: The correct answer is vertebral column only. Floating ribs (11th and 12th pairs) are attached posteriorly to thoracic vertebrae but have no anterior attachment to the sternum or cartilage. They provide protection for kidneys and other organs located in the upper abdominal cavity.
3. The scapula articulates with which of the following bones?
1. Humerus and clavicle
2. Sternum and clavicle
3. Radius and ulna
4. Humerus and sternum
Explanation: The scapula articulates with the humerus at the glenoid cavity and with the clavicle at the acromion process, forming the shoulder girdle. This joint provides wide mobility for the upper limb movements such as rotation, abduction, and flexion, essential for functional arm motion.
4. The pectoral girdle consists of:
1. Clavicle and scapula
2. Scapula and humerus
3. Clavicle and sternum
4. Scapula and rib
Explanation: The correct answer is clavicle and scapula. These bones form the pectoral girdle, attaching the upper limbs to the axial skeleton. The clavicle acts as a strut, while the scapula supports the arm. This arrangement allows maximum mobility of the shoulder joint in multiple planes.
5. The pelvic girdle is formed by:
1. Ilium, ischium, and pubis
2. Femur and tibia
3. Sacrum and coccyx
4. Sternum and ribs
Explanation: The correct answer is ilium, ischium, and pubis. These three bones fuse to form the coxal bone, constituting each half of the pelvic girdle. It supports the vertebral column, connects lower limbs to the trunk, and provides protection for urinary and reproductive organs.
6. Which of the following bones forms the shoulder joint with the humerus?
1. Clavicle
2. Scapula
3. Sternum
4. Rib
Explanation: The correct answer is scapula. The glenoid cavity of the scapula articulates with the head of the humerus to form the shoulder joint. This ball-and-socket joint allows rotational movements and is supported by muscles and ligaments ensuring stability and flexibility during arm movement.
Assertion-Reason Question
7. Assertion (A): Floating ribs do not attach to the sternum.
Reason (R): They are connected only to the vertebral column posteriorly.
1. Both A and R are true, and R explains A
2. Both A and R are true, but R does not explain A
3. A is true but R is false
4. A is false but R is true
Explanation: The correct answer is both A and R are true, and R explains A. Floating ribs (11th and 12th) are attached posteriorly to the vertebral column and have no anterior connection, giving flexibility and allowing expansion of the thoracic cavity during respiration.
Fill in the Blanks Question
8. The ______ ribs are attached indirectly to the sternum through the cartilage of the 7th rib.
1. Floating
2. True
3. Vertebrochondral
4. False
Explanation: The correct answer is vertebrochondral ribs. These are the 8th, 9th, and 10th pairs of ribs that connect indirectly to the sternum through the costal cartilage of the 7th rib. They provide flexibility to the thoracic cage and assist in protecting vital thoracic organs.
Choose the Correct Statements Question
9. Statement I: Scapula connects upper limbs to the axial skeleton.
Statement II: Coxal bones connect lower limbs to the vertebral column.
1. Both statements are correct
2. Both statements are incorrect
3. Statement I is correct, II is incorrect
4. Statement I is incorrect, II is correct
Explanation: Both statements are correct. The scapula forms part of the pectoral girdle, linking upper limbs to the axial skeleton, while the coxal bones form the pelvic girdle, joining lower limbs to the vertebral column through the sacrum, providing strength and balance for standing and walking.
Matching Type Question
10. Match the following:
A. True ribs I. Directly attached to sternum
B. False ribs II. Indirectly attached to sternum
C. Floating ribs III. Not attached anteriorly
1. A-I, B-II, C-III
2. A-II, B-I, C-III
3. A-III, B-II, C-I
4. A-II, B-III, C-I
Explanation: The correct answer is A-I, B-II, C-III. True ribs (1st–7th) directly attach to the sternum via costal cartilage, false ribs (8th–10th) are indirectly attached through cartilage of the 7th rib, and floating ribs (11th–12th) are not connected anteriorly, aiding flexibility during respiration.
Topic: Types of Joints; Subtopic: Structure and Function of Human Joints
Keyword Definitions:
Fibrous joints: Immovable joints where bones are connected by dense connective tissue, e.g., skull sutures.
Cartilaginous joints: Partly movable joints connected by cartilage, allowing limited movement, e.g., intervertebral discs.
Hinge joints: Uniaxial joints allowing movement in one plane, e.g., knee and elbow.
Ball and socket joints: Multiaxial joints allowing movement in multiple directions, e.g., shoulder and hip.
Synovial joints: Freely movable joints with a synovial cavity filled with fluid for lubrication.
Lead Question – 2024
Match List I with List II
List-I List-II
A. Fibrous joints I. Adjacent vertebrae, limited movement
B. Cartilaginous joints II. Humerus and Pectoral girdle, rotational movement
C. Hinge joints III. Skull, don’t allow any movement
D. Ball and socket joints IV. Knee, help in locomotion
Choose the correct answer from the options given below:
(1) A-I, B-III, C-II, D-IV
(2) A-II, B-III, C-I, D-IV
(3) A-III, B-I, C-IV, D-II
(4) A-IV, B-II, C-III, D-I
Answer and Explanation:
The correct answer is (3). Fibrous joints are immovable and found in the skull (A-III). Cartilaginous joints join vertebrae and allow limited movement (B-I). Hinge joints like the knee allow back-and-forth movement aiding locomotion (C-IV). Ball and socket joints in shoulder and hip permit rotation in multiple planes (D-II). These provide flexibility and strength to the skeleton.
1. Which of the following joints allows movement in all directions?
(1) Hinge joint
(2) Ball and socket joint
(3) Pivot joint
(4) Fibrous joint
Answer and Explanation:
The correct answer is (2). Ball and socket joints allow movement in all directions—flexion, extension, rotation, and circumduction. Found in the shoulder and hip, these joints consist of a spherical head fitting into a cup-like socket, offering maximum mobility and stability, essential for free limb movements like rotation and lifting.
2. Which joint connects the atlas and axis vertebrae?
(1) Hinge joint
(2) Pivot joint
(3) Saddle joint
(4) Ball and socket joint
Answer and Explanation:
The correct answer is (2). The pivot joint between the atlas (C₁) and axis (C₂) vertebrae enables rotation of the head. The odontoid process (dens) of the axis acts as a pivot around which the atlas rotates. This specialized joint provides head rotation while maintaining cervical stability.
3. The sutures of the skull are examples of:
(1) Cartilaginous joints
(2) Fibrous joints
(3) Synovial joints
(4) Ball and socket joints
Answer and Explanation:
The correct answer is (2). The sutures of the skull are fibrous joints that are immovable. They tightly join the cranial bones, protecting the brain. The dense connective tissue between bones prevents movement but allows slight flexibility during early development for brain growth and skull shaping.
4. Which joint helps in flexion and extension of the forearm?
(1) Ball and socket joint
(2) Hinge joint
(3) Pivot joint
(4) Gliding joint
Answer and Explanation:
The correct answer is (2). The hinge joint at the elbow allows uniaxial movement—flexion and extension. It functions like a mechanical hinge, permitting motion in one plane while restricting other directions. This ensures precise control and stability during activities like lifting or throwing.
5. Which type of joint is found between carpals of the wrist?
(1) Saddle joint
(2) Gliding joint
(3) Pivot joint
(4) Ball and socket joint
Answer and Explanation:
The correct answer is (2). Gliding joints between carpal bones allow limited sliding movements in multiple directions. They facilitate wrist flexibility, shock absorption, and smooth hand motions. The flat articular surfaces glide over each other without rotation, enabling fine adjustments during grip and wrist rotation.
6. Which joint is an example of biaxial movement?
(1) Saddle joint
(2) Hinge joint
(3) Pivot joint
(4) Fibrous joint
Answer and Explanation:
The correct answer is (1). The saddle joint, found in the thumb (carpometacarpal joint), allows biaxial movement—flexion-extension and adduction-abduction. Its unique shape permits opposition of the thumb, a feature essential for grasping and holding objects. This joint gives humans superior manual dexterity.
7. Assertion-Reason Type:
Assertion (A): Cartilaginous joints allow partial movement between bones.
Reason (R): These joints are held together by fibrous ligaments.
(1) Both A and R are true, and R is the correct explanation of A.
(2) Both A and R are true, but R is not the correct explanation of A.
(3) A is true, R is false.
(4) A is false, R is true.
Answer and Explanation:
The correct answer is (3). Cartilaginous joints allow partial movement because bones are joined by cartilage, not fibrous ligaments. Examples include intervertebral discs and pubic symphysis. Cartilage cushions and limits motion, ensuring both stability and flexibility in the skeletal framework.
8. Matching Type:
Match the following:
A. Pivot joint → (i) Skull
B. Fibrous joint → (ii) Atlas and axis
C. Hinge joint → (iii) Knee
D. Ball and socket joint → (iv) Hip
(1) A-(ii), B-(i), C-(iii), D-(iv)
(2) A-(iv), B-(ii), C-(i), D-(iii)
(3) A-(i), B-(iii), C-(ii), D-(iv)
(4) A-(ii), B-(iii), C-(iv), D-(i)
Answer and Explanation:
The correct answer is (1). Pivot joints are found between atlas and axis vertebrae enabling rotation, fibrous joints occur in the skull providing rigidity, hinge joints in the knee allow uniaxial movement, and ball and socket joints in the hip permit rotation and free movement in multiple directions.
9. Fill in the Blanks Type:
The joint that allows rotation of the head is the ______ joint.
(1) Hinge
(2) Pivot
(3) Ball and socket
(4) Gliding
Answer and Explanation:
The correct answer is (2). The pivot joint between the atlas and axis vertebrae enables head rotation. The odontoid process acts as a pivot, allowing rotational movement without lateral displacement. This articulation maintains spinal alignment while facilitating smooth rotation of the skull.
10. Choose the Correct Statements:
Statement I: Synovial fluid lubricates the joint surfaces.
Statement II: Synovial fluid is produced by cartilaginous tissue.
(1) Both statements are true
(2) Both statements are false
(3) Statement I true, Statement II false
(4) Statement I false, Statement II true
Answer and Explanation:
The correct answer is (3). Synovial fluid lubricates joint surfaces, reducing friction during movement. It is secreted by the synovial membrane, not cartilaginous tissue. This fluid nourishes cartilage and absorbs shocks, maintaining smooth and pain-free joint function during locomotion.
Topic: Muscular System; Subtopic: Types and Structure of Muscles
Keyword Definitions:
Skeletal Muscles: Voluntary, striated muscles attached to bones responsible for body movements such as walking and lifting.
Smooth Muscles: Involuntary, non-striated muscles found in walls of internal organs like the stomach, intestines, and blood vessels.
Cardiac Muscles: Striated, involuntary muscles found exclusively in the heart, responsible for rhythmic contractions that pump blood.
Triceps and Biceps: Skeletal muscles in the upper arm controlling forearm movement and extension.
Lead Question – 2024
Three types of muscles are given as a, b, and c. Identify the correct matching pair along with their location in the human body.
Name of muscle / location
(1) (a) Skeletal – Triceps
(b) Smooth – Stomach
(c) Cardiac – Heart
(2) (a) Skeletal – Biceps
(b) Involuntary – Intestine
(c) Smooth – Heart
(3) (a) Involuntary – Nost tip
(b) Skeletal – Bone
(c) Cardiac – Heart
(4) (a) Smooth – Toes
(b) Skeletal – Legs
(c) Cardiac – Heart
Explanation: The correct answer is (1) (a) Skeletal – Triceps, (b) Smooth – Stomach, (c) Cardiac – Heart. Skeletal muscles like triceps are voluntary and striated, smooth muscles in the stomach are involuntary and non-striated, and cardiac muscles in the heart are involuntary but striated. Each performs specialized functions vital for locomotion and circulation.
1. Which of the following is a voluntary muscle?
(1) Smooth muscle
(2) Skeletal muscle
(3) Cardiac muscle
(4) Intestinal muscle
Explanation: The correct answer is (2) Skeletal muscle. Skeletal muscles are voluntary as their movements are under conscious control. They attach to bones through tendons and show a striated appearance under a microscope. These muscles help in walking, posture maintenance, and body movement.
2. The muscle present in the walls of alimentary canal is:
(1) Cardiac muscle
(2) Smooth muscle
(3) Skeletal muscle
(4) Voluntary muscle
Explanation: The correct answer is (2) Smooth muscle. Smooth muscles line hollow organs such as the stomach and intestines. They are involuntary, meaning they contract automatically to regulate digestion and other internal movements without conscious control.
3. Which type of muscle is found in the heart?
(1) Smooth muscle
(2) Skeletal muscle
(3) Cardiac muscle
(4) Voluntary muscle
Explanation: The correct answer is (3) Cardiac muscle. Cardiac muscles are involuntary and striated with intercalated discs that synchronize heart contractions. These muscles are unique to the heart and function continuously throughout life to circulate blood efficiently.
4. Which of the following muscles is multinucleated?
(1) Cardiac muscle
(2) Smooth muscle
(3) Skeletal muscle
(4) None of these
Explanation: The correct answer is (3) Skeletal muscle. Skeletal muscle fibers are long, cylindrical, and multinucleated, meaning they contain more than one nucleus per cell. This helps in efficient protein synthesis and coordinated contraction for movement.
5. Which muscle type shows intercalated discs?
(1) Smooth
(2) Skeletal
(3) Cardiac
(4) None
Explanation: The correct answer is (3) Cardiac. Intercalated discs are unique junctional structures present in cardiac muscles. They allow rapid transmission of impulses between cardiac cells, ensuring coordinated and rhythmic contractions essential for effective pumping of blood by the heart.
6. Which muscles help in peristalsis?
(1) Skeletal muscles
(2) Cardiac muscles
(3) Smooth muscles
(4) Voluntary muscles
Explanation: The correct answer is (3) Smooth muscles. Smooth muscles in the digestive tract walls contract rhythmically in a wave-like motion known as peristalsis. This process propels food through the alimentary canal, facilitating digestion and absorption of nutrients.
7. (Assertion-Reason Type)
Assertion (A): Cardiac muscles are involuntary but striated.
Reason (R): They have intercalated discs that synchronize heart contractions.
(1) Both A and R are true, and R correctly explains A.
(2) Both A and R are true, but R does not explain A.
(3) A is true, R is false.
(4) A is false, R is true.
Explanation: The correct answer is (1). Both statements are true and related. Cardiac muscles are involuntary yet striated due to alternating light and dark bands. Intercalated discs allow coordinated rhythmic contractions ensuring continuous heartbeat and blood flow.
8. Match the muscle types with their characteristics:
A. Skeletal muscle — I. Non-striated, involuntary
B. Smooth muscle — II. Striated, voluntary
C. Cardiac muscle — III. Striated, involuntary
(1) A-I, B-II, C-III
(2) A-II, B-I, C-III
(3) A-III, B-I, C-II
(4) A-II, B-III, C-I
Explanation: The correct answer is (2). Skeletal muscles are striated and voluntary, smooth muscles are non-striated and involuntary, while cardiac muscles are striated and involuntary. These classifications are based on microscopic structure and control mechanism.
9. Fill in the blanks:
________ muscles are involuntary and non-striated, found in the walls of hollow organs.
(1) Skeletal
(2) Smooth
(3) Cardiac
(4) Voluntary
Explanation: The correct answer is (2) Smooth muscles. These muscles are spindle-shaped, lack striations, and work involuntarily to control movements in organs like the stomach, intestines, and blood vessels. They respond to autonomic nervous signals rather than conscious control.
10. Choose the correct statements:
Statement I: Skeletal muscles are voluntary and striated.
Statement II: Smooth muscles are involuntary and non-striated.
(1) Both statements are true.
(2) Both statements are false.
(3) Statement I is true, Statement II is false.
(4) Statement I is false, Statement II is true.
Explanation: The correct answer is (1). Skeletal muscles are voluntary, striated, and attached to bones enabling movement, while smooth muscles are involuntary, non-striated, and control internal organ functions. Their differences reflect adaptation to specialized physiological roles.
Topic: Skeletal System; Subtopic: Bones of Upper and Lower Limbs
Keyword Definitions:
• Palm bones (Metacarpals): The five long bones forming the middle part of the hand between the wrist and fingers.
• Wrist bones (Carpals): Eight small bones forming the wrist, connecting the hand to the forearm.
• Ankle bones (Tarsals): Seven bones forming the ankle, connecting the foot to the leg.
• Digit bones (Phalanges): Bones of fingers and toes; each finger has three, thumb has two.
• Skeletal system: The framework of bones that supports, protects organs, and facilitates movement.
Lead Question - 2023 (Manipur)
Match List - I with List - II
List-I List-II
(A) Palm bones (I) Phalanges
(B) Wrist bones (II) Metacarpals
(C) Ankle bones (III) Carpals
(D) Digit bones (IV) Tarsals
Choose the correct answer from the options given below:
Options:
1. II III I IV
2. IV I II III
3. III IV I II
4. II III IV I
Explanation:
The palm bones are the metacarpals, located between wrist and fingers (A-II). The wrist bones are carpals that form the joint connecting hand and forearm (B-III). The ankle bones are tarsals linking foot and leg (C-IV). The digit bones are phalanges, constituting fingers and toes (D-I). Understanding this mapping clarifies bone arrangement in upper and lower limbs, important for movement and structural support. Therefore, the correct option is 1.
1. Single Correct Answer MCQ:
Which bone connects the hand to the forearm?
1. Metacarpals
2. Carpals
3. Phalanges
4. Tarsals
Explanation:
The carpals form the wrist, connecting the hand to the forearm. They provide flexibility and articulation for hand movements. Metacarpals form the palm, phalanges are digits, and tarsals are ankle bones. Hence, option 2 is correct.
2. Single Correct Answer MCQ:
Which bones form the toes?
1. Carpals
2. Metacarpals
3. Phalanges
4. Tarsals
Explanation:
Phalanges constitute the fingers and toes. Each toe has three phalanges, except the big toe, which has two. They are distal to metatarsals in the foot. Hence, option 3 is correct.
3. Single Correct Answer MCQ:
Which bones make up the palm of the hand?
1. Carpals
2. Metacarpals
3. Phalanges
4. Tarsals
Explanation:
The metacarpals are the five long bones forming the palm between wrist and fingers. They are essential for hand structure and movement. Hence, option 2 is correct.
4. Single Correct Answer MCQ:
Which bones form the ankle joint?
1. Carpals
2. Metacarpals
3. Tarsals
4. Phalanges
Explanation:
The tarsals are seven bones forming the ankle, connecting the leg to the foot. They support body weight and allow movement. Hence, option 3 is correct.
5. Single Correct Answer MCQ:
Which is the distal bone of fingers?
1. Metacarpals
2. Carpals
3. Phalanges
4. Tarsals
Explanation:
The phalanges are the distal bones of fingers and toes. They are arranged as proximal, middle, and distal for each finger (except thumb). This structure aids in gripping and manipulation. Hence, option 3 is correct.
6. Single Correct Answer MCQ:
Which bone group forms the base of the hand?
1. Carpals
2. Metacarpals
3. Phalanges
4. Tarsals
Explanation:
The carpals form the base of the hand, articulating with the radius and ulna. They provide flexibility for wrist movement. Hence, option 1 is correct.
7. Assertion-Reason MCQ:
Assertion (A): Tarsals are weight-bearing bones.
Reason (R): Tarsals form the ankle and support the body's weight.
1. Both A and R are true and R is correct explanation of A
2. Both A and R are true but R is not correct explanation of A
3. A is true but R is false
4. Both A and R are false
Explanation:
The tarsals form the ankle and foot base, bearing body weight and allowing movement. This explains the assertion accurately. Hence, option 1 is correct.
8. Matching Type MCQ:
Match the bones with their location:
A. Metacarpals — (i) Palm
B. Phalanges — (ii) Fingers
C. Carpals — (iii) Wrist
D. Tarsals — (iv) Ankle
1. A-(i), B-(ii), C-(iii), D-(iv)
2. A-(ii), B-(i), C-(iv), D-(iii)
3. A-(iii), B-(iv), C-(i), D-(ii)
4. A-(iv), B-(iii), C-(ii), D-(i)
Explanation:
Metacarpals form the palm (A-i), phalanges form fingers (B-ii), carpals form wrist (C-iii), tarsals form ankle (D-iv). This correspondence ensures correct skeletal mapping. Hence, option 1 is correct.
9. Fill in the Blanks MCQ:
The bones of the wrist are called __________.
1. Metacarpals
2. Tarsals
3. Carpals
4. Phalanges
Explanation:
Carpals are the eight bones that form the wrist, connecting the forearm to the hand, allowing flexibility and movement. Hence, option 3 is correct.
10. Choose the correct statements MCQ:
Statement I: Metacarpals form the palm of the hand.
Statement II: Tarsals are part of the foot.
1. Both statements are true
2. Statement I is true, Statement II is false
3. Statement I is false, Statement II is true
4. Both statements are false
Explanation:
Metacarpals form the hand's palm (Statement I true) and tarsals form the ankle and part of the foot (Statement II true). Both statements accurately describe bone locations. Hence, option 1 is correct.
Topic: Muscular System; Subtopic: Skeletal Muscle Structure and Function
Keyword Definitions:
Skeletal muscle: Type of striated muscle attached to bones responsible for voluntary movements.
Fascicle: Bundle of muscle fibers surrounded by collagenous connective tissue.
Sarcomere: Functional contractile unit of a muscle fiber.
Sarcoplasmic reticulum: Specialized endoplasmic reticulum storing calcium ions in muscle fibers.
Actin: Thin filament protein involved in muscle contraction.
Myosin: Thick filament protein generating force during contraction.
M-line: Central part of sarcomere anchoring myosin filaments.
Striated appearance: Alternating light and dark bands seen in skeletal muscle.
Muscle fiber: Single elongated multinucleated cell of skeletal muscle.
Contraction: Shortening of muscle fibers generating force.
Collagen: Structural protein providing strength and support in connective tissue.
Lead Question (2023):
Which of the following statements are correct regarding skeletal muscle?
A. Muscle bundles are held together by collagenous connective tissue layer called fascicle.
B. Sarcoplasmic reticulum of muscle fibre is a store house of calcium ions.
C. Striated appearance of skeletal muscle fibre is due to distribution pattern of actin and myosin proteins.
D. M line is considered as functional unit of contraction called sarcomere.
(1) A, C and D only
(2) C and D only
(3) A, B and C only
(4) B and C only
Answer & Explanation: Option 3 is correct. Statements A, B, and C are true: muscle bundles are held together by fascicles, sarcoplasmic reticulum stores calcium ions necessary for contraction, and striated appearance results from alternating actin and myosin filaments. Statement D is incorrect; the sarcomere, not M-line, is the functional contractile unit. Understanding skeletal muscle organization, protein distribution, and calcium handling is essential for explaining muscle contraction mechanics, physiology, and disorders such as myopathies, muscular dystrophies, and excitation-contraction coupling abnormalities.
1. Single Correct Answer MCQ: Which filament forms the thin filaments in skeletal muscle sarcomere?
A) Myosin
B) Actin
C) Troponin
D) Tropomyosin
Answer & Explanation: Option B is correct. Actin is the thin filament in sarcomeres, interacting with myosin thick filaments during contraction. Troponin and tropomyosin regulate actin-myosin interactions, while myosin forms thick filaments generating force. Correct knowledge of filament types and their roles is critical for understanding muscle contraction, sliding filament theory, excitation-contraction coupling, and the effects of calcium release from sarcoplasmic reticulum on contraction dynamics.
2. Single Correct Answer MCQ: The sarcoplasmic reticulum stores which ion essential for muscle contraction?
A) Sodium
B) Potassium
C) Calcium
D) Magnesium
Answer & Explanation: Option C is correct. Sarcoplasmic reticulum stores calcium ions, which are released upon excitation to bind troponin, enabling actin-myosin cross-bridge formation and contraction. Sodium and potassium are critical for action potential propagation, but calcium is the primary ion directly regulating contraction. Calcium reuptake into the sarcoplasmic reticulum leads to muscle relaxation, highlighting its central role in excitation-contraction coupling and overall skeletal muscle physiology.
3. Single Correct Answer MCQ: What is the functional contractile unit of skeletal muscle?
A) Myofibril
B) Sarcomere
C) Fascicle
D) Muscle fiber
Answer & Explanation: Option B is correct. The sarcomere, delineated by Z-lines, is the smallest contractile unit, containing organized actin and myosin filaments. Myofibrils are chains of sarcomeres, fascicles are bundles of fibers, and muscle fibers are individual multinucleated cells. Understanding sarcomere structure is fundamental to explaining muscle contraction mechanics, striated appearance, cross-bridge cycling, and effects of calcium, ATP, and regulatory proteins in skeletal muscle physiology and pathology.
4. Single Correct Answer MCQ: Which connective tissue surrounds individual skeletal muscle fibers?
A) Epimysium
B) Perimysium
C) Endomysium
D) Fascicle
Answer & Explanation: Option C is correct. Endomysium is a thin layer of connective tissue surrounding individual muscle fibers, supporting capillaries and nerve fibers. Perimysium surrounds fascicles, and epimysium encloses the whole muscle. Proper organization of connective tissue ensures structural integrity, force transmission, and coordination during contraction. Knowledge of these layers is crucial for understanding muscle anatomy, mechanics, and pathological conditions such as muscular dystrophies.
5. Single Correct Answer MCQ: Which protein forms the thick filament of skeletal muscle?
A) Actin
B) Myosin
C) Troponin
D) Tropomyosin
Answer & Explanation: Option B is correct. Myosin forms the thick filaments that interact with actin thin filaments to generate force during contraction. Actin, troponin, and tropomyosin are components of thin filaments and regulatory proteins. Understanding filament composition is essential for explaining sliding filament theory, force generation, ATP usage, and muscular diseases involving protein mutations or cross-bridge defects.
6. Single Correct Answer MCQ: What is responsible for striated appearance of skeletal muscle?
A) Arrangement of myofibrils
B) Connective tissue layers
C) Mitochondrial distribution
D) Nerve innervation
Answer & Explanation: Option A is correct. The striated appearance results from the regular arrangement of sarcomeres in myofibrils, producing alternating A-bands (dark) and I-bands (light) visible under a microscope. Connective tissue, mitochondria, and nerve fibers support function but do not create striations. Recognizing this structural pattern is key for understanding muscle physiology, contraction mechanics, and microscopic identification of normal and pathological muscle tissue.
7. Assertion-Reason MCQ:
Assertion (A): Sarcomere is the functional unit of skeletal muscle contraction.
Reason (R): Actin and myosin filaments within sarcomere slide past each other during contraction.
A) Both A and R are true and R is the correct explanation of A
B) Both A and R are true but R is not the correct explanation of A
C) A is true but R is false
D) A is false but R is true
Answer & Explanation: Option A is correct. Sarcomeres, bordered by Z-lines, are the contractile units of skeletal muscle. During contraction, actin thin filaments slide over myosin thick filaments, shortening the sarcomere length and generating force. This sliding filament mechanism explains muscle shortening and force production, making sarcomere the functional unit. Understanding this principle is fundamental to muscle physiology, excitation-contraction coupling, and interpreting muscle pathology.
8. Matching Type MCQ: Match muscle structures with their functions:
List I - List II
A. Sarcoplasmic reticulum - I. Stores calcium ions
B. M-line - II. Anchors myosin filaments
C. Z-line - III. Delimits sarcomere
Choose correct option:
1) A-I, B-II, C-III
2) A-II, B-III, C-I
3) A-III, B-I, C-II
4) A-I, B-III, C-II
Answer & Explanation: Option 1 is correct. Sarcoplasmic reticulum stores calcium ions (A-I), M-line anchors myosin filaments (B-II), and Z-line demarcates sarcomere boundaries (C-III). Matching structural elements with their functions is essential to understand contraction mechanics, calcium regulation, and sarcomere organization in skeletal muscles, which underpins studies of physiology, histology, and muscular disorders.
9. Fill in the Blanks MCQ: The _______ surrounds a bundle of muscle fibers forming a fascicle.
A) Epimysium
B) Perimysium
C) Endomysium
D) Sarcolemma
Answer & Explanation: Option B is correct. Perimysium is connective tissue surrounding a fascicle, supporting blood vessels and nerves. Endomysium surrounds individual fibers, epimysium encloses the entire muscle, and sarcolemma is the muscle fiber membrane. Knowledge of connective tissue organization is critical for understanding structural integrity, force transmission, and functional properties of skeletal muscles in physiology and pathology.
10. Choose the Correct Statements MCQ:
Statement I: Sarcoplasmic reticulum stores calcium ions required for contraction.
Statement II: M-line is the functional contractile unit of skeletal muscle.
A) Both statements are correct
B) Both statements are incorrect
C) Only Statement I is correct
D) Only Statement II is correct
Answer & Explanation: Option C is correct. Sarcoplasmic reticulum stores calcium ions necessary for actin-myosin interactions during contraction. The M-line, however, only anchors myosin filaments and is not the functional contractile unit; the sarcomere serves that role. Understanding these distinctions is crucial for comprehending contraction mechanisms, excitation-contraction coupling, and the structural-functional relationship in skeletal muscles.
Keyword Definitions:
Cartilaginous Joint: A joint where bones are connected by cartilage, allowing limited movement.
Ball and Socket Joint: A highly movable joint where a spherical head fits into a cup-like cavity.
Fibrous Joint: A joint connected by fibrous tissue, generally immovable.
Saddle Joint: A joint where articulating surfaces are shaped like a saddle, allowing movement in two planes.
Vertebral Column: The spine or backbone consisting of vertebrae.
Pectoral Girdle: The set of bones connecting the arm to the axial skeleton, includes scapula and clavicle.
Carpal Bones: The wrist bones.
Humerus: The upper arm bone articulating with scapula at the shoulder.
Flat Skull Bones: Bones of the skull that are flat in shape, connected by sutures.
Joint: A point where two or more bones meet, providing stability and mobility.
Metacarpal: The bones of the hand between wrist and fingers.
Lead Question - 2023
Match List I with List II.
List I (Type of joint) | List II (Found between)
A. Cartilaginous Joint | I. Between flat skull bones
B. Ball and Socket Joint | II. Between adjacent vertebrae in vertebral column
C. Fibrous Joint | III. Between carpal and metacarpal of thumb
D. Saddle Joint | IV. Between Humerus and Pectoral girdle
Choose the correct answer from the options given below:
(1) A-I, B-IV, C-III, D-II
(2) A-II, B-IV, C-III, D-I
(3) A-III, B-I, C-II, D-IV
(4) A-II, B-IV, C-I, D-III
Answer & Explanation: (1) A-I, B-IV, C-III, D-II.
Cartilaginous joints are found between flat skull bones (sutures in adults fuse). Ball and socket joint is at the shoulder (Humerus and Pectoral girdle) allowing rotational movement. Fibrous joints, like between carpal and metacarpal of the thumb, are strong and limited in motion. Saddle joints, such as between adjacent vertebrae in the vertebral column, allow slight movement in two planes, providing flexibility and support. These classifications explain the relation between structure and function in human joints, ensuring stability, mobility, and proper biomechanical function for daily activities.
1. Which type of joint allows the greatest range of motion?
(1) Fibrous Joint
(2) Cartilaginous Joint
(3) Ball and Socket Joint
(4) Saddle Joint
Ball and socket joints, such as shoulder and hip, allow the widest range of motion in multiple directions including rotation, flexion, extension, abduction, and adduction. Fibrous joints are immovable, cartilaginous joints allow limited motion, and saddle joints permit movement in two planes. This functional design enables complex limb movements necessary for daily activities.
2. Which of the following joints is immovable?
(1) Fibrous Joint
(2) Cartilaginous Joint
(3) Ball and Socket Joint
(4) Saddle Joint
Fibrous joints, such as sutures in the skull, are immovable (synarthroses). Their fibrous connective tissue tightly binds bones together, providing stability and protecting the brain. In contrast, cartilaginous joints allow slight movement, while ball and socket and saddle joints are highly movable, facilitating complex motions.
3. Cartilaginous joints are mainly found in:
(1) Skull bones
(2) Vertebrae
(3) Shoulder
(4) Wrist
Cartilaginous joints are mainly found between vertebrae, where intervertebral discs of cartilage allow limited movement, absorb shock, and provide flexibility to the spine. While some flat skull bones fuse with sutures (fibrous), true cartilaginous joints connect bones with hyaline or fibrocartilage for stability and slight motion.
4. Assertion-Reason Type:
Assertion (A): Saddle joints allow movement in two planes.
Reason (R): Articulating surfaces resemble a saddle, enabling biaxial motion.
(1) Both A and R are true and R explains A
(2) Both A and R are true but R does not explain A
(3) A is true but R is false
(4) A is false but R is true
Both A and R are true and R explains A. Saddle joints, like the carpometacarpal joint of the thumb, have concave and convex articulating surfaces, permitting movement in two planes: flexion-extension and abduction-adduction, which is critical for precise thumb function and grasping.
5. Fill in the blanks:
The ______ joint connects Humerus with Pectoral girdle, while the ______ joint is found between carpal and metacarpal of the thumb.
(1) Ball and Socket, Fibrous
(2) Saddle, Cartilaginous
(3) Ball and Socket, Saddle
(4) Fibrous, Ball and Socket
The ball and socket joint connects Humerus with Pectoral girdle (shoulder), enabling rotational motion. The saddle joint is found between carpal and metacarpal of the thumb, allowing biaxial movement essential for gripping and precision handling. These joints are structurally adapted for mobility and function.
6. Which joint type is found between flat skull bones in adults?
(1) Ball and Socket Joint
(2) Fibrous Joint
(3) Cartilaginous Joint
(4) Saddle Joint
In adults, flat skull bones are joined by fibrous joints called sutures. These immovable joints provide stability and protect the brain while allowing minimal growth during childhood. They ossify with age but retain limited flexibility to absorb mechanical stress.
7. Which joint type allows biaxial movement?
(1) Ball and Socket Joint
(2) Saddle Joint
(3) Fibrous Joint
(4) Cartilaginous Joint
Saddle joints allow biaxial movement, including
Topic: Musculoskeletal System; Subtopic: Bones, Ligaments, Tendons, and Adipose Tissue
Keyword Definitions:
• Bone: Rigid organ forming part of the vertebrate skeleton, supports and protects tissues.
• Limb bones: Bones of arms and legs that support weight and facilitate movement.
• Ligament: Fibrous connective tissue connecting bones to other bones.
• Tendon: Fibrous tissue attaching muscles to bones.
• Adipose tissue: Specialized connective tissue for fat storage.
• Hematopoiesis: Production of blood cells, occurs in bone marrow.
• Cartilage: Flexible connective tissue found in joints, rib cage, and ear.
• Osteocytes: Mature bone cells maintaining bone tissue.
Lead Question - 2022 (Ganganagar)
Choose the correct statements:
(a) Bones support and protect softer tissues and organs
(b) Weight bearing function is served by limb bones
(c) Ligament is the site of production of blood cells
(d) Adipose tissue is specialised to store fats
(e) Tendons attach one bone to another
Choose the most appropriate answer from the options given below:
1. (a), (b) and (d) only
2. (b), (c) and (e) only
3. (a), (c) and (d) only
4. (a), (b) and (e) only
Explanation: The correct answer is option 1. Bones provide structural support to the body and protect vital organs, while limb bones bear the body's weight during standing and movement. Adipose tissue functions as an energy store and insulation. Ligaments connect bones to other bones and do not produce blood cells, which occurs in bone marrow. Tendons connect muscles to bones, not bone to bone. Understanding these distinctions is crucial in anatomy and physiology as each connective tissue has specialized roles in movement, support, protection, and metabolic functions, maintaining overall skeletal and systemic health.
1. Single Correct Answer MCQ:
Which connective tissue attaches muscles to bones?
1. Ligament
2. Tendon
3. Cartilage
4. Bone marrow
Explanation: The correct answer is tendon. Tendons are fibrous connective tissues that attach muscles to bones, transmitting force to enable movement. Ligaments connect bones to bones, cartilage cushions joints, and bone marrow produces blood cells.
2. Single Correct Answer MCQ:
Which tissue stores energy in the form of fat?
1. Cartilage
2. Ligament
3. Adipose tissue
4. Bone
Explanation: The correct answer is adipose tissue. Adipose tissue is specialized to store energy as fat, provide insulation, and cushion organs. Cartilage supports joints, ligaments connect bones, and bones provide structural support.
3. Single Correct Answer MCQ:
Hematopoiesis occurs in which site?
1. Ligament
2. Tendon
3. Bone marrow
4. Adipose tissue
Explanation: The correct answer is bone marrow. Hematopoiesis, the production of blood cells, occurs in the red bone marrow within bones. Ligaments and tendons do not produce blood cells, and adipose tissue stores fat.
4. Single Correct Answer MCQ:
Which bones primarily bear the body's weight?
1. Skull bones
2. Rib bones
3. Limb bones
4. Vertebrae
Explanation: The correct answer is limb bones. Limb bones, including femur and tibia in the legs, support and bear the body's weight during standing and locomotion. Skull bones protect the brain, ribs protect thoracic organs, and vertebrae support the torso.
5. Single Correct Answer MCQ:
Which structure connects one bone to another?
1. Tendon
2. Ligament
3. Cartilage
4. Bone
Explanation: The correct answer is ligament. Ligaments are fibrous connective tissues that join bones together at joints, providing stability and preventing excessive movement. Tendons attach muscle to bone, cartilage cushions joints, and bone itself provides support.
6. Single Correct Answer MCQ:
Bones serve primarily to:
1. Store fat
2. Produce tendons
3. Support and protect organs
4. Produce enzymes
Explanation: The correct answer is support and protect organs. Bones form the skeleton providing structural framework and protecting vital organs such as brain, heart, and lungs. Fat storage occurs in adipose tissue, tendons are fibrous tissues, and enzymes are produced by glands, not bones.
7. Assertion-Reason MCQ:
Assertion (A): Ligaments connect bones at joints.
Reason (R): Ligaments are elastic and help stabilize joints.
1. Both A and R are correct and R explains A
2. Both A and R are correct but R does not explain A
3. A correct, R incorrect
4. A incorrect, R correct
Explanation: The correct answer is option 1. Ligaments are fibrous connective tissues that connect bones at joints, providing stability and preventing excessive movement. Their elasticity allows controlled flexibility, making R a correct explanation for A.
8. Matching Type MCQ:
Match tissue with its function:
(a) Bone - (i) Energy storage
(b) Ligament - (ii) Connect bones
(c) Tendon - (iii) Attach muscle to bone
(d) Adipose tissue - (iv) Support and protect organs
1. (a)-(iv), (b)-(ii), (c)-(iii), (d)-(i)
2. (a)-(i), (b)-(iv), (c)-(ii), (d)-(iii)
3. (a)-(ii), (b)-(iii), (c)-(i), (d)-(iv)
4. (a)-(iii), (b)-(i), (c)-(iv), (d)-(ii)
Explanation: The correct answer is option 1. Bone supports and protects organs, ligaments connect bones, tendons attach muscles to bones, and adipose tissue stores energy in the form of fat, fulfilling their specific structural and metabolic functions.
9. Fill in the Blanks MCQ:
The ________ is specialized to store fats and provide insulation.
1. Ligament
2. Adipose tissue
3. Tendon
4. Bone
Explanation: The correct answer is adipose tissue. Adipose tissue stores triglycerides, provides insulation, and cushions organs. Ligaments connect bones, tendons attach muscles, and bones provide structural support and protection.
10. Choose the Correct Statements MCQ:
Statement I: Bones protect vital organs.
Statement II: Tendons connect bones to bones.
1. Only Statement I correct
2. Only Statement II correct
3. Both correct
4. Both incorrect
Explanation: The correct answer is option 1. Bones provide protection to vital organs, whereas tendons connect muscles to bones. Ligaments, not tendons, connect bones to bones. This distinction is important in understanding the musculoskeletal system and its functions in movement and support.
Topic: Disorders of Bones and Joints; Subtopic: Gout and Related Conditions
Keyword Definitions:
• Gout: Metabolic disorder characterized by accumulation of uric acid crystals in joints causing inflammation.
• Uric acid: End product of purine metabolism, high levels can form crystals in joints.
• Inflammation: Body's response to injury or infection, causing redness, swelling, and pain.
• Osteoporosis: Condition of weakened bones due to decreased bone mass.
• Cartilage degeneration: Breakdown of cartilage in joints leading to osteoarthritis.
• Joints: Sites of articulation between bones allowing movement.
• Metabolic disorder: Condition caused by abnormal chemical reactions in the body.
• Crystal deposition: Accumulation of solid crystals in tissues causing pain.
• Purine metabolism: Biochemical process that produces uric acid from purine nucleotides.
• Hyperuricemia: Excessive uric acid in blood leading to gout.
• Anti-inflammatory treatment: Therapy used to reduce inflammation in joints.
Lead Question - 2022 (Ganganagar)
Gout is a type of disorder which leads to:
1. Inflammation of joints due to accumulation of uric acid crystals
2. Weakening of bones due to decreased bone mass
3. Inflammation of joints due to cartilage degeneration
4. Weakening of bones due to low calcium level
Explanation: Gout is caused by accumulation of uric acid crystals in joints, leading to severe inflammation, redness, and pain. Unlike osteoporosis, which weakens bones, or osteoarthritis, which involves cartilage degeneration, gout specifically involves purine metabolism imbalance and hyperuricemia. Management includes lifestyle modifications and anti-inflammatory drugs to prevent crystal deposition. Correct answer is 1.
1. Single Correct Answer MCQ:
Which condition is caused by decreased bone mass?
a) Gout
b) Osteoporosis
c) Osteoarthritis
d) Rheumatoid arthritis
Explanation: Osteoporosis is characterized by decreased bone density, making bones fragile. Gout involves uric acid crystals, osteoarthritis involves cartilage degeneration. Correct answer is b.
2. Single Correct Answer MCQ:
Uric acid accumulation primarily affects which part of the body?
a) Bones
b) Joints
c) Muscles
d) Lungs
Explanation: Excess uric acid forms crystals in joints, triggering inflammation and pain. Bones and muscles are indirectly affected. Correct answer is b.
3. Single Correct Answer MCQ:
Which metabolic disorder results in hyperuricemia?
a) Diabetes
b) Gout
c) Hypothyroidism
d) Anemia
Explanation: Gout is a metabolic disorder causing elevated uric acid in blood (hyperuricemia), leading to crystal deposition in joints. Correct answer is b.
4. Single Correct Answer MCQ:
Which treatment is primarily used to reduce joint inflammation in gout?
a) Calcium supplements
b) Anti-inflammatory drugs
c) Antibiotics
d) Insulin therapy
Explanation: Anti-inflammatory drugs alleviate pain and swelling in gouty joints. Calcium supplements address osteoporosis. Correct answer is b.
5. Single Correct Answer MCQ:
What is the main biochemical cause of gout?
a) Excess calcium
b) Uric acid crystal deposition
c) Collagen deficiency
d) Vitamin D deficiency
Explanation: Gout arises from uric acid crystals forming in joints due to purine metabolism imbalance. Calcium or collagen deficiency causes other disorders. Correct answer is b.
6. Single Correct Answer MCQ:
Which dietary factor increases risk of gout?
a) High purine intake
b) Low protein diet
c) Low carbohydrate diet
d) High fiber intake
Explanation: High purine foods like red meat and seafood elevate uric acid levels, triggering gout attacks. Correct answer is a.
7. Assertion-Reason MCQ:
Assertion (A): Gout causes severe joint inflammation.
Reason (R): Uric acid crystals deposit in joints triggering immune response.
a) Both A and R true, R explains A
b) Both A and R true, R does not explain A
c) A true, R false
d) Both false
Explanation: Both statements are true; uric acid crystal deposition causes inflammation in joints, making R the correct explanation. Correct answer is a.
8. Matching Type MCQ:
Match List-I with List-II:
List-I | List-II
(a) Gout | (i) Uric acid crystals
(b) Osteoporosis | (ii) Low bone mass
(c) Osteoarthritis | (iii) Cartilage degeneration
(d) Rheumatoid arthritis | (iv) Autoimmune joint inflammation
Options:
1. a-i, b-ii, c-iii, d-iv
2. a-ii, b-i, c-iv, d-iii
3. a-iii, b-iv, c-i, d-ii
4. a-iv, b-iii, c-ii, d-i
Explanation: Gout (uric acid crystals), Osteoporosis (low bone mass), Osteoarthritis (cartilage degeneration), Rheumatoid arthritis (autoimmune). Correct answer is 1.
9. Fill in the Blanks / Completion MCQ:
Gout occurs due to accumulation of _______ in joints.
a) Calcium crystals
b) Uric acid crystals
c) Collagen fibers
d) Sodium salts
Explanation: Gout results from uric acid crystal deposition in joints, causing inflammation and pain. Correct answer is b.
10. Choose the correct statements MCQ (Statement I & II):
Statement I: Gout is caused by uric acid crystal deposition.
Statement II: Osteoporosis involves low bone density.
a) Both I and II correct
b) Only I correct
c) Only II correct
d) Both incorrect
Explanation: Both statements accurately describe gout and osteoporosis respectively, highlighting differences between metabolic and bone disorders. Correct answer is a.
Topic: Muscular System; Subtopic: Mechanism of Muscle Contraction
Keyword Definitions:
• Sliding Filament Theory: Explanation of muscle contraction where actin filaments slide over myosin filaments causing sarcomere shortening.
• Actin Filament: Thin filament in muscle fibers involved in contraction.
• Myosin Filament: Thick filament in muscle fibers responsible for force generation.
• Sarcomere: Functional unit of a muscle fiber between two Z-lines.
• A–band: Region of sarcomere containing the entire length of myosin filament.
• I–band: Light region of sarcomere containing only actin filaments.
• Z-line: Boundary of sarcomere where actin filaments are anchored.
• Cross-bridge: Connection formed between actin and myosin heads during contraction.
• ATP: Energy molecule required for cross-bridge cycling.
• Muscle Contraction: Process where muscle fibers generate tension and shorten.
• Force Generation: Production of mechanical tension during muscle contraction.
Lead Question - 2022 (Ganganagar)
According to the sliding filament theory:
1. Actin and myosin filaments slide over each other to increase the length of the sarcomere.
2. Length of A–band does not change.
3. I–band increases in length.
4. The actin filaments slide away from A–band resulting in shortening of sarcomere.
Explanation: Sliding filament theory states that during contraction, actin filaments slide over myosin filaments causing shortening of sarcomeres, while the length of A–band remains constant. I–band and H–zone decrease in length. Statement 1 is incorrect because sarcomere length decreases, not increases. Statement 2 is correct. Statement 3 is incorrect; I–band shortens. Statement 4 is partially misleading. The key point is actin filaments slide over myosin, shortening sarcomere while maintaining A–band length. Correct answer is 2.
1. Single Correct Answer MCQ:
Which filament's length remains constant during contraction?
a) Actin
b) Myosin
c) Both actin and myosin
d) Neither
Explanation: During contraction, actin slides over myosin. The length of the myosin filament, forming the A–band, remains constant. Correct answer is b.
2. Single Correct Answer MCQ:
During muscle contraction, the sarcomere:
a) Lengthens
b) Shortens
c) Remains the same
d) Disintegrates
Explanation: Sliding filament mechanism causes sarcomere shortening by sliding actin over myosin. This results in overall muscle contraction. Correct answer is b.
3. Single Correct Answer MCQ:
Which band decreases in length during contraction?
a) A–band
b) I–band
c) M–line
d) Myosin filament
Explanation: I–band contains only actin filaments, which slide over myosin during contraction, shortening the I–band. Correct answer is b.
4. Single Correct Answer MCQ:
The energy for cross-bridge cycling comes from:
a) ATP
b) GTP
c) Glucose
d) NADH
Explanation: ATP hydrolysis provides energy for myosin heads to bind and pull actin filaments, enabling sarcomere shortening. Correct answer is a.
5. Single Correct Answer MCQ:
What forms the boundary of a sarcomere?
a) M–line
b) Z–line
c) H–zone
d) A–band
Explanation: Z–lines anchor actin filaments and mark sarcomere boundaries. Correct answer is b.
6. Single Correct Answer MCQ:
Which zone disappears during maximal contraction?
a) A–band
b) H–zone
c) I–band
d) Sarcomere
Explanation: H–zone, the central part of A–band with only myosin, disappears as actin filaments slide toward the center during contraction. Correct answer is b.
7. Assertion-Reason MCQ:
Assertion (A): Sarcomere shortens during muscle contraction.
Reason (R): Actin filaments slide over myosin filaments.
a) Both A and R true, R explains A
b) Both A and R true, R does not explain A
c) A true, R false
d) Both false
Explanation: Sarcomere shortening occurs because actin filaments slide over myosin filaments, generating contraction. Both A and R are true and R explains A. Correct answer is a.
8. Matching Type MCQ:
Match List-I with List-II:
List-I | List-II
(a) A–band | (i) Length decreases
(b) I–band | (ii) Length constant
(c) H–zone | (iii) Shortens
(d) Sarcomere | (iv) Functional unit of muscle
Options:
1. a-ii, b-i, c-iii, d-iv
2. a-i, b-ii, c-iii, d-iv
3. a-iii, b-i, c-ii, d-iv
4. a-iv, b-ii, c-i, d-iii
Explanation: A–band length remains constant (ii), I–band shortens (i), H–zone shortens (iii), sarcomere is functional unit (iv). Correct answer is 1.
9. Fill in the Blanks / Completion MCQ:
The sliding filament theory was proposed to explain __________.
a) Muscle elongation
b) Muscle contraction
c) Nerve conduction
d) Bone formation
Explanation: Sliding filament theory explains muscle contraction mechanism via actin and myosin interaction. Correct answer is b.
10. Choose the correct statements MCQ (Statement I & II):
Statement I: During contraction, actin slides over myosin filaments.
Statement II: A–band shortens during contraction.
a) Both I and II correct
b) Only I correct
c) Only II correct
d) Both incorrect
Explanation: Statement I is correct; Statement II is incorrect as A–band remains constant. Correct answer is b.
Topic: Muscular System; Subtopic: Muscle Contraction Mechanism
Keyword Definitions:
Actin: Protein forming thin filaments in muscle fibers, interacts with myosin for contraction.
Myosin: Motor protein forming thick filaments, generates force during muscle contraction through cross-bridge cycling.
Z-line: Structure at each end of sarcomere anchoring thin filaments and defining sarcomere boundaries.
Sarcoplasmic Reticulum: Specialized endoplasmic reticulum in muscle storing and releasing calcium ions for contraction.
Acetylcholine: Neurotransmitter released at neuromuscular junction to trigger muscle contraction, stored in vesicles, not sarcoplasmic reticulum.
Calcium Binding Sites: Found on troponin in thin filaments, essential for initiating contraction, not on myosin cross-bridges.
Thin Filament: Filament in muscle composed mainly of actin, troponin, and tropomyosin, responsible for sliding past thick filament.
Thick Filament: Filament composed mainly of myosin, responsible for generating force through ATP-driven interactions with actin.
Lead Question - 2022 (Abroad)
Which of the following is correct statement ?
1. Actin and regulatory proteins are located in thin filament.
2. Z-lines anchor myosin (thick) filament to the ends of the sarcomere.
3. Sarcoplasmic reticulum stores acetylcholine.
4. Myosin cross bridges contain calcium binding sites.
Explanation: The correct answer is Actin and regulatory proteins are located in thin filament. In skeletal muscles, thin filaments are composed of actin along with regulatory proteins troponin and tropomyosin, which control contraction by exposing myosin-binding sites. Z-lines anchor thin filaments, not thick myosin filaments. Sarcoplasmic reticulum stores calcium, not acetylcholine. Calcium binds to troponin on thin filaments, not myosin cross-bridges. The sliding filament mechanism relies on ATP-driven interactions between actin (thin) and myosin (thick) filaments, regulated by calcium binding to troponin, ensuring coordinated contraction and relaxation cycles in skeletal muscles.
1. Single Correct Answer Type:
Which protein forms thick filaments in skeletal muscle?
1. Actin
2. Myosin
3. Troponin
4. Tropomyosin
Explanation: The correct answer is Myosin. Myosin molecules assemble into thick filaments in skeletal muscle sarcomeres. These filaments interact with actin thin filaments to generate contraction through ATP-powered cross-bridge cycling. Troponin and tropomyosin are regulatory proteins in thin filaments. Actin forms thin filaments and provides binding sites for myosin. This structure enables the sliding filament mechanism crucial for muscle contraction, making myosin essential for force generation in muscles and a key target in studies of muscle physiology and related disorders.
2. Single Correct Answer Type:
What is the main function of the sarcoplasmic reticulum in muscle fibers?
1. Store acetylcholine
2. Release calcium ions
3. Anchor thick filaments
4. Produce ATP
Explanation: The correct answer is Release calcium ions. The sarcoplasmic reticulum is a specialized endoplasmic reticulum in muscle cells that stores calcium ions. Upon stimulation by a nerve impulse, it releases calcium into the sarcoplasm, initiating contraction by binding to troponin on thin filaments. It does not store acetylcholine, anchor thick filaments, or produce ATP. Calcium release and reuptake regulate contraction and relaxation cycles, and proper functioning is essential for effective muscle contraction, excitation-contraction coupling, and overall muscle physiology.
3. Single Correct Answer Type:
Which structure anchors thin filaments in a sarcomere?
1. M-line
2. Z-line
3. Sarcoplasmic reticulum
4. T-tubules
Explanation: The correct answer is Z-line. Z-lines are boundaries of sarcomeres and anchor the thin filaments (actin) at each end. M-line anchors thick filaments (myosin). Sarcoplasmic reticulum stores calcium, while T-tubules transmit action potentials into the muscle fiber. Proper anchoring at Z-lines ensures sarcomere stability and allows efficient force transmission during contraction. Misalignment can cause impaired contraction, demonstrating the importance of Z-lines in structural integrity and function of skeletal muscles.
4. Single Correct Answer Type:
Where are calcium binding sites located in skeletal muscle?
1. Myosin cross-bridges
2. Troponin on thin filaments
3. Tropomyosin on thick filaments
4. Actin filaments
Explanation: The correct answer is Troponin on thin filaments. Calcium ions released from the sarcoplasmic reticulum bind to troponin, causing a conformational change that moves tropomyosin off myosin-binding sites on actin filaments. This allows myosin cross-bridges to bind actin, generating contraction. Myosin cross-bridges do not bind calcium. The precise location of calcium binding is essential for controlled contraction and relaxation cycles in skeletal muscles, forming a central mechanism in excitation-contraction coupling and proper muscular function.
5. Single Correct Answer Type:
Which protein regulates myosin binding to actin in skeletal muscle?
1. Myosin
2. Troponin
3. Tropomyosin
4. Both Troponin and Tropomyosin
Explanation: The correct answer is Both Troponin and Tropomyosin. Troponin binds calcium, causing tropomyosin to shift, exposing myosin-binding sites on actin. This regulation ensures that contraction occurs only when calcium levels rise. Myosin provides force but does not regulate binding. This coordinated interaction is essential for the sliding filament mechanism, enabling controlled muscle contraction and relaxation. Disruption can result in impaired muscle function and highlights the importance of regulatory proteins in skeletal muscle physiology.
6. Single Correct Answer Type:
Which molecule initiates muscle contraction by binding to troponin?
1. ATP
2. Acetylcholine
3. Calcium ions
4. ADP
Explanation: The correct answer is Calcium ions. Calcium released from the sarcoplasmic reticulum binds to troponin on thin filaments, inducing a conformational change that moves tropomyosin, exposing myosin-binding sites on actin. Acetylcholine triggers the action potential but does not directly bind troponin. ATP fuels myosin head movement, and ADP is a hydrolysis product. Calcium’s role is critical in excitation-contraction coupling, enabling the initiation of contraction at the molecular level and coordinating the precise timing of sarcomere shortening in skeletal muscles.
7. Assertion-Reason Type:
Assertion (A): Tropomyosin blocks myosin-binding sites on actin in resting muscle.
Reason (R): Troponin binds calcium ions to move tropomyosin and expose myosin-binding sites.
1. Both A and R are correct, and R is the correct explanation of A
2. Both A and R are correct, but R is not the correct explanation of A
3. A is correct, R is false
4. A is false, R is true
Explanation: Correct answer is Both A and R are correct, and R is the correct explanation of A. Tropomyosin covers myosin-binding sites in relaxed muscle. When calcium binds troponin, it induces a conformational change moving tropomyosin away, allowing myosin to attach to actin and generate contraction. This process underlies the regulation of skeletal muscle contraction and is essential for coordinated force generation during excitation-contraction coupling. The interplay between troponin, tropomyosin, calcium, and actin ensures precise control of muscle contraction.
8. Matching Type:
Match the structure with its function:
A. Z-line → (i) Store calcium
B. Sarcoplasmic reticulum → (ii) Anchor thin filaments
Topic: Human Muscular System
Subtopic: Muscular Disorders and Diseases
Keyword Definitions:
Tetanus: A condition causing involuntary muscle contractions due to low calcium or bacterial toxins affecting motor neurons.
Myasthenia gravis: An autoimmune disorder that weakens skeletal muscles by interfering with acetylcholine receptors.
Muscular dystrophy: A genetic disorder causing progressive degeneration and weakening of muscles.
Arthritis: Inflammation of one or more joints causing pain and stiffness, especially with age or autoimmune causes.
Calcium ions (Ca²⁺): Essential for muscle contraction by binding to troponin, exposing binding sites for actin-myosin interaction.
Lead Question – 2022
Which of the following is a correct match for disease and its symptoms:
(1) Tetanus – high Ca²⁺ level causing rapid spasms
(2) Myasthenia gravis – Genetic disorder resulting in weakening and paralysis of skeletal muscle
(3) Muscular dystrophy – An autoimmune disorder causing progressive degeneration of skeletal muscle
(4) Arthritis – Inflamed joints
Explanation: Arthritis is a disorder characterized by inflammation of joints, causing swelling, stiffness, and pain. It is the correct match among the given options, while others describe wrong associations of cause and nature. Therefore, the correct answer is (4) Arthritis – Inflamed joints.
1. Which of the following is an autoimmune disorder affecting neuromuscular junctions?
(1) Myasthenia gravis
(2) Tetanus
(3) Muscular dystrophy
(4) Osteoarthritis
Explanation: Myasthenia gravis is an autoimmune disease that blocks acetylcholine receptors at neuromuscular junctions, causing muscle weakness. The correct answer is (1).
2. The genetic disorder resulting in progressive muscle degeneration is:
(1) Myasthenia gravis
(2) Muscular dystrophy
(3) Arthritis
(4) Gout
Explanation: Muscular dystrophy is caused by defective genes responsible for muscle structure and repair, leading to gradual muscle degeneration. The correct answer is (2).
3. Which of the following occurs due to sustained muscle contraction without relaxation?
(1) Muscle fatigue
(2) Muscle twitch
(3) Tetanus
(4) Cramp
Explanation: Tetanus occurs when muscle fibers remain contracted for a long duration due to continuous stimulation or bacterial toxin. The correct answer is (3).
4. Inflammation of joints leading to stiffness and pain is known as:
(1) Myalgia
(2) Osteoporosis
(3) Arthritis
(4) Rickets
Explanation: Arthritis is a condition characterized by joint inflammation and stiffness, often due to aging, autoimmune response, or infection. Hence, the correct answer is (3).
5. Which ion is essential for initiating muscle contraction?
(1) Sodium
(2) Potassium
(3) Calcium
(4) Magnesium
Explanation: Calcium ions play a crucial role in muscle contraction by binding to troponin, exposing actin binding sites for myosin cross-bridge formation. Hence, the correct answer is (3).
6. Which of the following is a bacterial disease affecting muscles?
(1) Tetanus
(2) Myasthenia gravis
(3) Arthritis
(4) Muscular dystrophy
Explanation: Tetanus is caused by Clostridium tetani, whose toxin affects motor neurons and causes continuous muscle spasms. Hence, the correct answer is (1).
7. Assertion (A): Myasthenia gravis is an autoimmune disorder affecting skeletal muscles.
Reason (R): It destroys acetylcholine receptors, reducing nerve impulse transmission.
(1) Both A and R are true and R explains A
(2) Both A and R are true but R does not explain A
(3) A is true but R is false
(4) A is false but R is true
Explanation: Both statements are true and the reason correctly explains the assertion, as receptor damage causes reduced muscle contraction. Hence, the correct answer is (1).
8. Match the following:
A. Tetanus — (i) Genetic muscle degeneration
B. Myasthenia gravis — (ii) Autoimmune disorder
C. Muscular dystrophy — (iii) Bacterial toxin
D. Arthritis — (iv) Joint inflammation
Options:
(1) A-(iii), B-(ii), C-(i), D-(iv)
(2) A-(i), B-(iii), C-(iv), D-(ii)
(3) A-(ii), B-(i), C-(iii), D-(iv)
(4) A-(iv), B-(ii), C-(i), D-(iii)
Explanation: Tetanus results from bacterial toxins, Myasthenia gravis is autoimmune, Muscular dystrophy is genetic, and Arthritis involves joint inflammation. Hence, the correct answer is (1).
9. Fill in the blank:
In Myasthenia gravis, _______ receptors are blocked by antibodies.
(1) Dopamine
(2) Serotonin
(3) Acetylcholine
(4) Epinephrine
Explanation: In Myasthenia gravis, acetylcholine receptors at neuromuscular junctions are blocked by autoantibodies, leading to muscle weakness. Hence, the correct answer is (3).
10. Choose the correct statements:
(1) Arthritis affects joints.
(2) Myasthenia gravis is bacterial.
(3) Muscular dystrophy is autoimmune.
(4) Tetanus is genetic.
Explanation: Arthritis causes joint inflammation, Myasthenia gravis is autoimmune, Muscular dystrophy is genetic, and Tetanus is bacterial. Hence, only statement (1) is correct.
Topic: Skeletal System and Bone Disorders
Subtopic: Osteoporosis and Hormonal Influence
Keyword Definitions:
• Osteoporosis: Condition characterized by decreased bone mass and increased fragility.
• Bone mass: The density and strength of bones.
• Fracture: Break or crack in a bone.
• Estrogen: Primary female sex hormone that helps maintain bone density.
• Calcium: Mineral essential for bone strength.
• Vitamin D: Vitamin necessary for calcium absorption in bones.
• Bone remodeling: Continuous process of bone formation and resorption.
• Osteoclast: Cell that breaks down bone tissue.
• Osteoblast: Cell that forms new bone.
• Hormonal imbalance: Disruption in hormone levels affecting body functions.
Lead Question (2022):
Given below are two statements: one is labelled as Assertion (A) and the other as Reason (R).
Assertion (A): Osteoporosis is characterised by decreased bone mass and increased chances of fractures.
Reason (R): Common cause of osteoporosis is increased levels of estrogen.
(1) Both (A) and (R) are correct but (R) is not the correct explanation (A)
(2) (A) is correct but (R) is not correct
(3) (A) is not correct but (R) is correct
(4) Both (A) and (R) are correct and (R) is the correct explanation of (A)
Explanation: The correct answer is (2). Osteoporosis involves decreased bone mass, making bones fragile and more prone to fractures. However, increased estrogen does not cause osteoporosis; rather, decreased estrogen levels, especially after menopause, are a common cause. Hence, the assertion is correct, but the reason is incorrect.
Guessed MCQs:
1. Single Correct Answer:
Which hormone deficiency is a major cause of osteoporosis in postmenopausal women?
(a) Testosterone
(b) Estrogen
(c) Progesterone
(d) Cortisol
Explanation: The correct answer is (b). Decreased estrogen levels after menopause reduce bone density, leading to osteoporosis and higher fracture risk.
2. Single Correct Answer:
Which cell type is primarily responsible for bone resorption in osteoporosis?
(a) Osteoblast
(b) Osteocyte
(c) Osteoclast
(d) Chondrocyte
Explanation: The correct answer is (c). Osteoclasts break down bone tissue, and excessive activity relative to osteoblasts leads to decreased bone mass in osteoporosis.
3. Single Correct Answer:
Which nutrient deficiency worsens osteoporosis?
(a) Vitamin C
(b) Calcium
(c) Iron
(d) Vitamin K
Explanation: The correct answer is (b). Calcium deficiency reduces bone mineral density, aggravating osteoporosis and increasing susceptibility to fractures.
4. Assertion-Reason MCQ:
Assertion (A): Postmenopausal women are at higher risk of osteoporosis.
Reason (R): Decreased estrogen levels accelerate bone loss.
(a) Both A and R are correct and R explains A
(b) Both A and R are correct but R does not explain A
(c) A is correct, R is incorrect
(d) A is incorrect, R is correct
Explanation: The correct answer is (a). After menopause, estrogen levels drop, accelerating bone resorption by osteoclasts, increasing osteoporosis risk.
5. Single Correct Answer:
Which of the following is a preventive measure for osteoporosis?
(a) Weight-bearing exercises
(b) Smoking
(c) Excess alcohol
(d) Sedentary lifestyle
Explanation: The correct answer is (a). Weight-bearing exercises stimulate bone formation and increase bone density, helping prevent osteoporosis.
6. Single Correct Answer:
Which vitamin is essential for calcium absorption and bone health?
(a) Vitamin A
(b) Vitamin D
(c) Vitamin C
(d) Vitamin K
Explanation: The correct answer is (b). Vitamin D facilitates calcium absorption in the gut, maintaining bone mineral density and preventing osteoporosis.
7. Matching Type:
Match the following:
Column A
1. Osteoblast
2. Osteoclast
3. Calcium
4. Estrogen
Column B
A. Promotes bone formation
B. Breaks down bone
C. Mineral essential for bones
D. Hormone that maintains bone density
Options:
(a) 1-A, 2-B, 3-C, 4-D
(b) 1-B, 2-A, 3-D, 4-C
(c) 1-A, 2-B, 3-D, 4-C
(d) 1-B, 2-A, 3-C, 4-D
Explanation: The correct answer is (a). Osteoblast forms bone (1-A), osteoclast breaks bone (2-B), calcium is essential mineral (3-C), estrogen maintains bone density (4-D).
8. Fill in the Blanks:
Osteoporosis is characterized by decreased _______ and increased risk of _______.
(a) Bone mass, fractures
(b) Muscle mass, injuries
(c) Bone mass, infections
(d) Cartilage, fractures
Explanation: The correct answer is (a). Osteoporosis reduces bone mass and increases fragility, making bones prone to fractures, especially in elderly individuals.
9. Single Correct Answer:
Which lifestyle factor aggravates osteoporosis?
(a) Balanced diet
(b) Regular exercise
(c) Smoking
(d) Sunlight exposure
Explanation: The correct answer is (c). Smoking accelerates bone loss and reduces estrogen levels, increasing osteoporosis risk and fracture susceptibility.
10. Choose the correct statements:
(a) Osteoporosis involves decreased bone mass
(b) Decreased estrogen levels increase osteoporosis risk
(c) High calcium and vitamin D intake prevent osteoporosis
(d) Osteoporosis is caused by increased estrogen
Explanation: The correct answer is (a), (b), and (c). Osteoporosis results from decreased bone mass, aggravated by low estrogen, and can be mitigated with calcium and vitamin D intake.
Topic: Skeletal System
Subtopic: Vertebral Column and Joints
Keyword Definitions:
• Vertebral Column: Series of bones (vertebrae) forming the backbone and protecting the spinal cord.
• Cartilage: Flexible connective tissue found between bones providing cushioning and reducing friction.
• Areolar Tissue: Loose connective tissue supporting organs and blood vessels.
• Smooth Muscle: Involuntary muscle found in internal organs controlling movements.
• Intercalated Discs: Specialized junctions between cardiac muscle cells for synchronized contraction.
• Joint: Site where two or more bones meet enabling movement.
• Disc (Intervertebral): Fibrocartilaginous structure between vertebrae absorbing shocks.
• Ligament: Fibrous tissue connecting bones and stabilizing joints.
• Spinal Cord: Nervous tissue transmitting signals between brain and body.
• Vertebra: Individual bones forming the vertebral column.
Lead Question (2022):
Which of the following is present between the adjacent bones of the vertebral column?
(1) Cartilage
(2) Areolar tissue
(3) Smooth muscle
(4) Intercalated discs
Explanation: The correct answer is (1). Cartilage, specifically fibrocartilage forming intervertebral discs, is located between adjacent vertebrae. It acts as a cushion, absorbs shocks, allows slight movement, and prevents friction between bones, thus maintaining flexibility and strength of the vertebral column.
Guessed MCQs:
1. Single Correct Answer:
Which connective tissue cushions joints and absorbs shocks?
(a) Cartilage
(b) Ligament
(c) Areolar tissue
(d) Tendon
Explanation: The correct answer is (a). Cartilage, especially fibrocartilage, acts as a cushion in joints and between vertebrae, reducing friction, absorbing shocks, and allowing smooth movement of bones, thus maintaining structural integrity of the skeletal system.
2. Single Correct Answer:
Which type of cartilage is present in intervertebral discs?
(a) Fibrocartilage
(b) Hyaline
(c) Elastic
(d) Articular
Explanation: The correct answer is (a). Fibrocartilage, strong and resilient, forms intervertebral discs between vertebrae, providing cushioning, flexibility, and resistance to compression, helping maintain proper posture and spinal integrity.
3. Assertion-Reason MCQ:
Assertion (A): Intervertebral discs contain fibrocartilage.
Reason (R): Fibrocartilage provides cushioning and absorbs mechanical stress.
(a) Both A and R are correct, R explains A
(b) Both A and R are correct, R does not explain A
(c) A is correct, R is false
(d) A is false, R is true
Explanation: The correct answer is (a). Intervertebral discs are made of fibrocartilage, which cushions vertebrae, absorbs shocks, and allows flexibility. This tissue ensures stability and prevents damage to the vertebral column during movement.
4. Matching Type MCQ:
Match the tissue with its location:
A. Cartilage – (i) Between vertebrae
B. Areolar tissue – (ii) Under skin and around organs
C. Smooth muscle – (iii) Walls of internal organs
D. Intercalated discs – (iv) Heart muscle
Options:
1. A–i, B–ii, C–iii, D–iv
2. A–ii, B–i, C–iv, D–iii
3. A–iii, B–iv, C–ii, D–i
4. A–iv, B–iii, C–ii, D–i
Explanation: The correct answer is (1). Cartilage cushions vertebrae, areolar tissue supports organs, smooth muscle is found in organ walls, and intercalated discs connect cardiac muscle cells for coordinated heart contractions.
5. Single Correct Answer:
What connects bones and stabilizes joints?
(a) Ligaments
(b) Tendons
(c) Cartilage
(d) Areolar tissue
Explanation: The correct answer is (a). Ligaments are strong fibrous connective tissues that connect bones, stabilizing joints and preventing excessive movement, complementing cartilage that cushions bones at joints.
6. Single Correct Answer:
Which structure in vertebrae allows slight movement while maintaining stability?
(a) Intervertebral disc
(b) Tendon
(c) Smooth muscle
(d) Areolar tissue
Explanation: The correct answer is (a). Intervertebral discs, made of fibrocartilage, provide cushioning and slight flexibility, enabling movement of vertebrae while preventing friction and absorbing mechanical stress.
7. Fill in the Blanks:
The intervertebral ________ is made of fibrocartilage and absorbs shocks between vertebrae.
(a) disc
(b) ligament
(c) tendon
(d) muscle
Explanation: The correct answer is (a). Intervertebral discs, consisting of fibrocartilage, cushion the vertebrae, absorb mechanical shocks, and permit limited movement, ensuring spinal stability and protecting the spinal cord.
8. Single Correct Answer:
Which tissue type is not present between vertebrae?
(a) Smooth muscle
(b) Cartilage
(c) Fibrocartilage
(d) Nucleus pulposus
Explanation: The correct answer is (a). Smooth muscle is absent between vertebrae; instead, intervertebral discs with fibrocartilage and a gelatinous nucleus pulposus provide cushioning and shock absorption.
9. Single Correct Answer:
Which part of intervertebral disc acts as a shock absorber?
(a) Nucleus pulposus
(b) Ligament
(c) Tendon
(d) Articular cartilage
Explanation: The correct answer is (a). The nucleus pulposus, the gelatinous core of the intervertebral disc, distributes pressure evenly and absorbs mechanical shocks between adjacent vertebrae.
10. Choose the correct statements:
(a) Intervertebral discs are fibrocartilaginous.
(b) Cartilage prevents friction between bones.
(c) Smooth muscles are present between vertebrae.
(d) Ligaments connect and stabilize bones.
Options:
1. a, b, d only
2. a and c only
3. b and c only
4. All statements
Explanation: The correct answer is (1). Intervertebral discs are fibrocartilaginous, cartilage prevents bone friction, and ligaments stabilize joints. Smooth muscles are not present between vertebrae, so statement (c) is incorrect.
Topic: Human Skeletal System
Subtopic: Types of Bones and Joints
Keyword Definitions:
Scapula: A large triangular flat bone of the shoulder girdle.
Cranium: Part of the skull protecting the brain, joined by fibrous joints.
Sternum: Flat bone in the thoracic region where ribs attach anteriorly.
Vertebral column: Bony structure made of vertebrae, connected by cartilaginous joints.
Flat bone: Bone type providing protection and muscle attachment, e.g., sternum.
Fibrous joints: Immovable joints connected by dense connective tissue.
Cartilaginous joints: Slightly movable joints connected by cartilage, e.g., vertebrae.
Axial skeleton: Skeleton including skull, vertebral column, ribs, and sternum.
Appendicular skeleton: Bones of limbs and girdles connecting them to axial skeleton.
Bone classification: Bones classified into long, short, flat, and irregular types.
Joint: Point of articulation between bones enabling movement or stability.
Lead Question - 2021
Match List - I with List - II
List - I List - II
(a) Scapula (i) Cartilaginous joints
(b) Cranium (ii) Flat bone
(c) Sternum (iii) Fibrous joints
(d) Vertebral column (iv) Triangular flat bone
Choose the correct answer from the options given below
(1) (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i)
(2) (a)-(iv), (b)-(ii), (c)-(iii), (d)-(i)
(3) (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)
(4) (a)-(i), (b)-(iii), (c)-(ii), (d)-(iv)
Explanation: Scapula is a triangular flat bone (a-iv). Cranium bones are joined by fibrous joints (b-iii). Sternum is a flat bone (c-ii). Vertebral column has cartilaginous joints (d-i). Therefore, the correct matching is (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i). Correct answer is option (3).
1. Single Correct Answer:
Which of the following is a flat bone?
(1) Femur
(2) Sternum
(3) Radius
(4) Humerus
Explanation: Sternum is a flat bone forming the anterior part of the thoracic cage. Femur and humerus are long bones, radius is also a long bone. Correct answer is option (2).
2. Single Correct Answer:
Fibrous joints are found in:
(1) Knee
(2) Skull sutures
(3) Vertebrae
(4) Shoulder
Explanation: Fibrous joints are immovable and found in skull sutures where bones are tightly joined by connective tissue. Knee and shoulder have synovial joints, vertebrae have cartilaginous joints. Correct answer is option (2).
3. Single Correct Answer:
Vertebral column joints are mainly:
(1) Fibrous
(2) Cartilaginous
(3) Synovial
(4) Ball and socket
Explanation: Vertebrae are joined by cartilaginous joints allowing slight movement and providing flexibility with stability. Fibrous joints are immovable, synovial joints allow free movement, ball and socket is a type of synovial joint. Correct answer is option (2).
4. Single Correct Answer:
Scapula articulates with:
(1) Sternum
(2) Humerus
(3) Vertebral column
(4) Ribs
Explanation: Scapula articulates with the humerus at the glenoid cavity forming the shoulder joint. It does not directly articulate with sternum, vertebral column, or ribs. Correct answer is option (2).
5. Single Correct Answer:
Which type of skeleton includes scapula?
(1) Axial skeleton
(2) Appendicular skeleton
(3) Both
(4) None
Explanation: Scapula belongs to the appendicular skeleton, forming the shoulder girdle that connects arms to axial skeleton. Axial skeleton includes skull, vertebral column, sternum, and ribs. Correct answer is option (2).
6. Single Correct Answer:
Which joint allows free movement in multiple directions?
(1) Hinge joint
(2) Fibrous joint
(3) Ball and socket joint
(4) Cartilaginous joint
Explanation: Ball and socket joints allow free movement in all directions, such as shoulder and hip joints. Hinge joints allow unidirectional movement, fibrous joints are immovable, cartilaginous allow slight movement. Correct answer is option (3).
7. Assertion-Reason:
Assertion (A): Sternum is a flat bone.
Reason (R): Flat bones provide protection to organs and surface for muscle attachment.
(1) Both A and R true, R explains A
(2) Both A and R true, R does not explain A
(3) A true, R false
(4) A false, R true
Explanation: Sternum is a flat bone that protects the heart and lungs and provides muscle attachment. The reason correctly explains the assertion. Correct answer is option (1).
8. Matching Type:
Match the bone with its classification:
(a) Femur - 1. Long bone
(b) Sternum - 2. Flat bone
(c) Vertebra - 3. Irregular bone
(d) Patella - 4. Sesamoid bone
Options:
(1) a-1, b-2, c-3, d-4
(2) a-2, b-3, c-1, d-4
(3) a-1, b-4, c-2, d-3
(4) a-3, b-1, c-4, d-2
Explanation: Femur is a long bone, sternum a flat bone, vertebra irregular bone, patella sesamoid bone. Correct answer is option (1).
9. Fill in the Blank:
The immovable joints of the skull are called _____.
(1) Sutures
(2) Cartilage
(3) Synovial joints
(4) Ligaments
Explanation: Immovable joints of the skull are fibrous joints known as sutures, tightly binding bones. Correct answer is option (1).
10. Choose the correct statements:
(a) Vertebrae are connected by cartilaginous joints.
(b) Scapula is part of axial skeleton.
(c) Sternum is a flat bone.
(d) Cranium joints are fibrous.
Options:
(1) a, b, c
(2) a, c, d
(3) b, c, d
(4) a, b, d
Explanation: Vertebrae have cartilaginous joints (a), scapula belongs to appendicular not axial skeleton (b false), sternum is flat (c), cranium joints are fibrous (d). Correct statements are (a, c, d). Correct answer is option (2).
Topic: Muscle Contraction
Subtopic: Sliding Filament Theory
Keyword Definitions:
H-zone: Central part of sarcomere containing only thick filaments, disappears during contraction.
A-band: Dark band of sarcomere, length remains constant during contraction.
I-band: Light band consisting of thin filaments, narrows during contraction.
Z-line: Boundary of sarcomere where actin filaments are anchored.
Myosin: Motor protein that hydrolyzes ATP to power muscle contraction.
ATP hydrolysis: Energy-releasing reaction providing force for cross-bridge cycling.
Sarcomere: Functional unit of myofibril between two Z-lines.
Sliding filament theory: Explains contraction by sliding of actin over myosin filaments.
Cross-bridge cycle: Attachment, pivoting, and detachment of myosin heads from actin.
Actin: Thin filament protein that interacts with myosin during contraction.
Muscle contraction: Process of shortening muscle fibers through actin-myosin interaction.
Lead Question - 2021
During muscular contraction which of the following events occur?
(a) 'H' zone disappears
(b) 'A' band widens
(c) 'I' band reduces in width
(d) Myosin hydrolyzes ATP, releasing the ADP and Pi
(e) Z-lines attached to actins are pulled inwards
Choose the correct answer from the options given below.
(1) (a), (b), (c), (d) only
(2) (b), (c), (d), (e) only
(3) (b), (d), (e), (a) only
(4) (a), (c), (d), (e) only
Explanation: During contraction, H-zone disappears, I-band shortens, myosin hydrolyzes ATP for energy, and Z-lines are pulled inward. A-band length remains constant, not widened. Therefore, correct combination is (a), (c), (d), and (e). Correct answer is option (4).
1. Single Correct Answer:
Which band remains unchanged during muscle contraction?
(1) I-band
(2) H-zone
(3) A-band
(4) Z-line
Explanation: The A-band corresponds to the length of thick filaments and remains unchanged during contraction. I-band shortens, H-zone disappears, and Z-lines move closer. Correct answer is option (3).
2. Single Correct Answer:
Which molecule provides direct energy for muscle contraction?
(1) ADP
(2) ATP
(3) Creatine
(4) Glucose
Explanation: ATP directly powers muscle contraction by hydrolysis through myosin heads. ADP, creatine, and glucose are indirectly involved but do not directly supply energy for contraction. Correct answer is option (2).
3. Single Correct Answer:
Cross-bridge cycle involves binding of:
(1) Actin with tropomyosin
(2) Myosin head with actin
(3) ATP with troponin
(4) Calcium with ATP
Explanation: Cross-bridge formation occurs when the myosin head attaches to the actin filament, powered by ATP hydrolysis. Other options are unrelated to the cycle. Correct answer is option (2).
4. Single Correct Answer:
Which ion regulates binding of actin and myosin?
(1) Sodium
(2) Potassium
(3) Calcium
(4) Magnesium
Explanation: Calcium binds to troponin, causing tropomyosin to move away and expose actin-binding sites, enabling myosin to bind. This regulation is essential for contraction. Correct answer is option (3).
5. Single Correct Answer:
During contraction, Z-lines:
(1) Move closer together
(2) Move farther apart
(3) Remain unchanged
(4) Disappear completely
Explanation: Z-lines are pulled inward during contraction as actin filaments slide over myosin, reducing sarcomere length. They do not remain unchanged or disappear. Correct answer is option (1).
6. Single Correct Answer:
ATP is hydrolyzed by:
(1) Actin filament
(2) Troponin
(3) Myosin head
(4) Tropomyosin
Explanation: Myosin head contains ATPase activity that hydrolyzes ATP into ADP and Pi, releasing energy for contraction. Actin, troponin, and tropomyosin lack ATPase activity. Correct answer is option (3).
7. Assertion-Reason:
Assertion (A): I-band shortens during muscle contraction.
Reason (R): Actin filaments slide inward over myosin.
(1) Both A and R true, R explains A
(2) Both A and R true, R does not explain A
(3) A true, R false
(4) A false, R true
Explanation: I-band shortens as actin filaments slide inward during contraction, reducing the zone of only thin filaments. The reason directly explains the assertion. Correct answer is option (1).
8. Matching Type:
Match the structure with its change during contraction:
(a) H-zone - 1. Disappears
(b) I-band - 2. Shortens
(c) A-band - 3. Remains constant
(d) Z-lines - 4. Move closer
Options:
(1) a-1, b-2, c-3, d-4
(2) a-2, b-1, c-4, d-3
(3) a-4, b-3, c-2, d-1
(4) a-3, b-2, c-1, d-4
Explanation: H-zone disappears (a-1), I-band shortens (b-2), A-band remains constant (c-3), and Z-lines move closer (d-4). Correct answer is option (1).
9. Fill in the Blank:
During contraction, the _____ zone disappears.
(1) I-band
(2) A-band
(3) H-zone
(4) Z-line
Explanation: The H-zone disappears during contraction as actin filaments slide into the central region of the sarcomere, overlapping myosin completely. Correct answer is option (3).
10. Choose the correct statements:
(a) A-band length changes
(b) H-zone disappears
(c) Z-lines move inward
(d) I-band shortens
Options:
(1) a, b, c
(2) b, c, d
(3) a, c, d
(4) b, d only
Explanation: A-band remains unchanged, while H-zone disappears, I-band shortens, and Z-lines move inward during contraction. Therefore, correct statements are (b, c, d). Correct answer is option (2).
Autoimmune disorder: Disease where the immune system attacks the body’s own cells.
Neuromuscular junction: Synapse between motor neuron and skeletal muscle fiber.
Myasthenia gravis: Autoimmune disorder causing weakness due to impaired transmission at neuromuscular junction.
Muscular dystrophy: Genetic disorder leading to progressive muscle degeneration.
Gout: Disorder due to uric acid crystal deposition in joints.
Arthritis: Inflammation of joints causing pain and stiffness.
Acetylcholine: Neurotransmitter essential for nerve impulse transmission at neuromuscular junction.
Fatigue: Decreased ability of muscle to generate force.
Paralysis: Loss of muscle function due to nerve or muscle defect.
Autoantibodies: Antibodies that mistakenly target self-antigens.
Acetylcholine receptor: Protein at muscle membrane necessary for nerve-muscle communication.
Lead Question - 2021
Chronic autoimmune disorder affecting neuromuscular junction leading to fatigue, weakening and paralysis of skeletal muscle is called as:
Options:
(1) Muscular dystrophy
(2) Myasthenia gravis
(3) Gout
(4) Arthritis
Explanation: The autoimmune disease Myasthenia gravis targets acetylcholine receptors at neuromuscular junction, impairing nerve-muscle communication. This results in muscle fatigue, weakness, and sometimes paralysis. It differs from muscular dystrophy, gout, and arthritis, which have different causes. Answer: Myasthenia gravis.
1. Single Correct Answer MCQ: Which neurotransmitter is affected in Myasthenia gravis?
Options:
A. Dopamine
B. Acetylcholine
C. Serotonin
D. GABA
Explanation: In Myasthenia gravis, acetylcholine receptors are blocked by autoantibodies, preventing proper nerve-muscle transmission. Answer: Acetylcholine.
2. Single Correct Answer MCQ: Muscular dystrophy primarily arises due to:
Options:
A. Autoimmunity
B. Genetic defects
C. Viral infections
D. Vitamin deficiency
Explanation: Muscular dystrophy is a genetic disorder, usually linked to dystrophin gene defects, causing progressive muscle wasting. Answer: Genetic defects.
3. Single Correct Answer MCQ: Which enzyme increases in blood due to arthritis-related inflammation?
Options:
A. Lipase
B. Uricase
C. Cyclooxygenase
D. Amylase
Explanation: In arthritis, inflammation involves cyclooxygenase enzymes, which promote prostaglandin production causing joint pain and stiffness. Answer: Cyclooxygenase.
4. Single Correct Answer MCQ: Which disorder is caused by uric acid crystal deposition?
Options:
A. Arthritis
B. Gout
C. Myasthenia gravis
D. Muscular dystrophy
Explanation: Gout results from uric acid crystal deposition in joints, leading to intense pain and swelling. Answer: Gout.
5. Single Correct Answer MCQ: Which immune component causes receptor destruction in Myasthenia gravis?
Options:
A. Autoantibodies
B. Cytokines
C. Complement proteins
D. T cells only
Explanation: In Myasthenia gravis, autoantibodies attack acetylcholine receptors, disrupting neuromuscular communication and weakening skeletal muscles. Answer: Autoantibodies.
6. Single Correct Answer MCQ: Which symptom is most specific for Myasthenia gravis?
Options:
A. Joint pain
B. Progressive muscle fatigue
C. Involuntary tremors
D. High uric acid
Explanation: The hallmark of Myasthenia gravis is progressive muscle fatigue that worsens with activity and improves with rest. Answer: Progressive muscle fatigue.
7. Assertion-Reason MCQ:
Assertion (A): Myasthenia gravis is an autoimmune disorder.
Reason (R): It is caused by genetic deletion of dystrophin gene.
Options:
A. Both A and R true, R explains A
B. Both A and R true, R not correct explanation
C. A true, R false
D. A false, R true
Explanation: Myasthenia gravis is autoimmune, but dystrophin deletion relates to muscular dystrophy, not this disorder. Answer: A true, R false.
8. Matching Type MCQ:
List I: a. Myasthenia gravis b. Gout c. Muscular dystrophy d. Arthritis
List II: i. Autoimmune fatigue ii. Uric acid deposition iii. Genetic muscle wasting iv. Joint inflammation
Options:
A. a-i, b-ii, c-iii, d-iv
B. a-ii, b-iii, c-iv, d-i
C. a-iii, b-i, c-iv, d-ii
D. a-iv, b-iii, c-i, d-ii
Explanation: Myasthenia gravis = autoimmune fatigue, Gout = uric acid deposition, Muscular dystrophy = genetic muscle wasting, Arthritis = joint inflammation. Answer: a-i, b-ii, c-iii, d-iv.
9. Fill in the Blanks MCQ: Chronic autoimmune neuromuscular disorder characterized by fatigue and weakness is _______.
Options:
A. Arthritis
B. Muscular dystrophy
C. Myasthenia gravis
D. Gout
Explanation: Myasthenia gravis causes fatigue and weakness due to autoimmune attack on acetylcholine receptors at neuromuscular junction. Answer: Myasthenia gravis.
10. Choose the correct statements MCQ:
Options:
A. Myasthenia gravis is autoimmune
B. Muscular dystrophy is genetic
C. Gout is due to uric acid deposition
D. Arthritis always arises from uric acid crystals
Select:
1. A, B, C
2. A, C, D
3. A, B, D
4. B, C, D
Explanation: Myasthenia gravis = autoimmune, Muscular dystrophy = genetic, Gout = uric acid deposition. Arthritis may have other causes like autoimmune inflammation, not always uric acid. Correct set: A, B, C. Answer: Option 1.
Subtopic: Bone Structure
Hollow bones: Bones with internal cavities, reducing weight and aiding flight.
Pneumatic bones: Air-filled bones connected to respiratory system in birds.
Hemidactylus: A genus of geckos, terrestrial lizard with solid bones.
Macropus: Marsupial, kangaroo, with strong solid bones for hopping.
Ornithorhynchus: Platypus, semi-aquatic mammal with solid bones.
Neophron: A vulture species with hollow and pneumatic long bones.
Long bones: Bones longer than wide, supporting weight and movement.
Avian adaptations: Hollow bones reduce weight for flight efficiency.
Vertebrates: Animals with backbone, having varied skeletal structures.
Osteology: Study of bones and their morphology.
Pneumatization: Process of air-filling in bones of birds.
Lead Question - 2021
Which one of the following organisms bears hollow and pneumatic long bones?
(1) Hemidactylus
(2) Macropus
(3) Ornithorhynchus
(4) Neophron
Explanation: Neophron, a vulture, has hollow and pneumatic long bones. These adaptations reduce weight for flight, connecting the bones with the respiratory system. Hemidactylus, Macropus, and Ornithorhynchus have solid bones for terrestrial or aquatic locomotion. Answer: Neophron.
1. Single Correct Answer MCQ: Hollow bones are characteristic of which class of animals?
Options:
A. Mammals
B. Amphibians
C. Birds
D. Reptiles
Explanation: Birds possess hollow bones to reduce weight and aid flight. Mammals, reptiles, and amphibians generally have solid bones. Answer: Birds.
2. Single Correct Answer MCQ: Pneumatic bones are connected to which system?
Options:
A. Circulatory
B. Respiratory
C. Digestive
D. Nervous
Explanation: Pneumatic bones in birds are air-filled and connected to the respiratory system, helping efficient respiration during flight. Other systems are unrelated. Answer: Respiratory.
3. Single Correct Answer MCQ: Which of the following has solid bones for terrestrial locomotion?
Options:
A. Neophron
B. Hemidactylus
C. Eagle
D. Pigeon
Explanation: Hemidactylus is a terrestrial gecko with solid bones supporting ground movement. Neophron, eagle, and pigeon have hollow bones for flight. Answer: Hemidactylus.
4. Single Correct Answer MCQ: Long bones are primarily adapted for:
Options:
A. Flight
B. Weight support and movement
C. Digestion
D. Respiration
Explanation: Long bones provide mechanical support and enable movement. In birds, they are hollow, but in terrestrial vertebrates, they mainly support weight. Answer: Weight support and movement.
5. Single Correct Answer MCQ: Pneumatization in bones is most commonly seen in:
Options:
A. Reptiles
B. Birds
C. Amphibians
D. Mammals
Explanation: Pneumatization refers to air-filled bones seen in birds, facilitating flight by reducing skeletal weight. Other classes lack this adaptation. Answer: Birds.
6. Single Correct Answer MCQ: Which bone type reduces overall body weight in flying animals?
Options:
A. Short bones
B. Long solid bones
C. Hollow bones
D. Irregular bones
Explanation: Hollow bones in birds and flying reptiles reduce skeletal weight, aiding flight efficiency. Solid and irregular bones do not provide this adaptation. Answer: Hollow bones.
7. Assertion-Reason MCQ:
Assertion (A): Neophron has pneumatic bones.
Reason (R): Hollow bones store fat for energy.
Options:
A. Both A and R true, R correct explanation
B. Both A and R true, R not correct explanation
C. A true, R false
D. A false, R true
Explanation: Neophron has pneumatic bones to reduce weight and aid flight. They do not store fat; that function is unrelated. Assertion true, reason false. Answer: A true, R false.
8. Matching Type MCQ:
List I: a. Neophron b. Macropus c. Ornithorhynchus d. Hemidactylus
List II: i. Hollow bones ii. Solid hopping bones iii. Solid aquatic bones iv. Solid terrestrial bones
Options:
A. a-i, b-ii, c-iii, d-iv
B. a-ii, b-i, c-iii, d-iv
C. a-iv, b-ii, c-i, d-iii
D. a-i, b-iv, c-ii, d-iii
Explanation: Neophron = hollow bones, Macropus = solid hopping bones, Ornithorhynchus = solid aquatic bones, Hemidactylus = solid terrestrial bones. Answer: a-i, b-ii, c-iii, d-iv.
9. Fill in the Blanks MCQ: Hollow and pneumatic bones are an adaptation for _______.
Options:
A. Swimming
B. Flight
C. Burrowing
D. Running
Explanation: Hollow and pneumatic bones reduce weight, aiding flight in birds. Swimming, burrowing, or running animals usually have solid bones. Answer: Flight.
10. Choose the correct statements MCQ:
Options:
A. Hollow bones occur in Neophron
B. Macropus has pneumatic bones
C. Hemidactylus has solid bones
D. Ornithorhynchus has solid bones
Select:
1. A, B
2. A, C, D
3. B, C
4. All of the above
Explanation: Neophron has hollow bones. Macropus has solid hopping bones. Hemidactylus has solid terrestrial bones. Ornithorhynchus has solid aquatic bones. Correct statements are A, C, D. Answer: A, C, D.
Subtopic: Skeletal Disorders and Muscular Diseases
Keyword Definitions:
Gout: A metabolic disorder caused by accumulation of uric acid crystals in joints, leading to inflammation and pain.
Osteoporosis: A skeletal disorder characterized by decreased bone density, often due to hormonal imbalance like low estrogen levels.
Tetany: A condition marked by muscle spasms due to low calcium ion concentration in blood.
Muscular dystrophy: A group of inherited genetic disorders causing progressive muscle weakness and degeneration.
Autoimmune disorder: A condition where the immune system mistakenly attacks the body's own cells and tissues.
Arthritis: Inflammation of joints causing pain, stiffness and reduced mobility.
Rickets: A childhood bone disorder due to vitamin D deficiency leading to weak and deformed bones.
Myasthenia Gravis: An autoimmune neuromuscular disorder causing weakness of skeletal muscles.
Scoliosis: Abnormal lateral curvature of the spine affecting posture.
Osteomalacia: Softening of bones in adults due to defective mineralization, often linked to vitamin D deficiency.
Lead Question - 2020 (COVID Reexam)
Match the following columns and select the correct option:
Column - I Column - II
(a) Gout (i) Decreased levels of estrogen
(b) Osteoporosis (ii) Low ions in the blood
(c) Tetany (iii) Accumulation of uric acid crystals
(d) Muscular dystrophy (iv) Autoimmune disorder
(v) Genetic disorder
1. (a)-(ii), (b)-(i), (c)-(iii), (d)-(iv)
2. (a)-(iii), (b)-(i), (c)-(ii), (d)-(v)
3. (a)-(iv), (b)-(v), (c)-(i), (d)-(ii)
4. (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)
Explanation:
The correct answer is option 2. Gout results from uric acid accumulation, osteoporosis is linked to decreased estrogen, tetany occurs due to hypocalcemia (low ions), and muscular dystrophy is a genetic disorder. These matches explain underlying causes of different skeletal and muscular conditions, helping to differentiate them clinically and conceptually.
1. Which vitamin deficiency is directly associated with rickets?
1. Vitamin A
2. Vitamin D
3. Vitamin K
4. Vitamin B12
Explanation:
The correct answer is Vitamin D. Rickets results from impaired bone mineralization due to deficiency of vitamin D, calcium or phosphate. It is common in children exposed to poor sunlight. Supplementation of vitamin D and calcium helps prevent and treat the condition, ensuring proper skeletal development and prevention of deformities.
2. Which of the following is an autoimmune disorder affecting skeletal muscles?
1. Myasthenia gravis
2. Osteoporosis
3. Gout
4. Rickets
Explanation:
The correct answer is Myasthenia gravis. It is caused when antibodies block or destroy acetylcholine receptors at neuromuscular junctions. This prevents effective muscle contraction, leading to weakness. The condition demonstrates how autoimmune reactions disrupt normal physiology and must be differentiated from metabolic or genetic skeletal disorders during diagnosis and management.
3. Osteomalacia occurs in adults due to deficiency of:
1. Vitamin B complex
2. Vitamin D
3. Vitamin K
4. Vitamin A
Explanation:
The correct answer is Vitamin D. Osteomalacia is the adult counterpart of rickets. It is caused by defective mineralization of bone matrix due to vitamin D deficiency. Patients experience bone pain, muscle weakness, and fractures. This highlights the importance of sunlight exposure and dietary supplementation for maintaining bone health across all ages.
4. Which joint disease is most commonly associated with aging?
1. Osteoarthritis
2. Rickets
3. Gout
4. Scoliosis
Explanation:
The correct answer is Osteoarthritis. It is the most common degenerative joint disease, caused by progressive wear and tear of cartilage. It leads to stiffness, joint pain, and reduced flexibility. Unlike autoimmune arthritis, osteoarthritis is primarily age-related, making lifestyle modification and physiotherapy important aspects of its management in elderly patients.
5. Scoliosis refers to:
1. Forward bending of spine
2. Lateral curvature of spine
3. Backward bending of spine
4. Inflammation of vertebrae
Explanation:
The correct answer is Lateral curvature of spine. Scoliosis can appear during growth spurts, especially in adolescence. It causes uneven shoulders, posture changes and sometimes respiratory difficulties in severe cases. Identifying scoliosis early allows bracing or corrective measures to prevent progression, distinguishing it from kyphosis or lordosis which are different curvatures.
6. Which of the following is a genetic disorder affecting muscle proteins?
1. Muscular dystrophy
2. Osteomalacia
3. Tetany
4. Rickets
Explanation:
The correct answer is Muscular dystrophy. It is caused by mutations in genes responsible for muscle proteins like dystrophin. Patients show progressive weakness, difficulty in mobility, and muscle wasting. Being a genetic condition, there is no permanent cure, but supportive therapies help improve quality of life and slow down progression of symptoms.
7. Assertion–Reason Question:
Assertion (A): Osteoporosis is common in postmenopausal women.
Reason (R): Estrogen deficiency accelerates bone resorption.
1. Both A and R are true, R is the correct explanation.
2. Both A and R are true, R is not the correct explanation.
3. A is true, R is false.
4. A is false, R is true.
Explanation:
The correct answer is option 1. Osteoporosis in postmenopausal women is primarily due to estrogen deficiency. Estrogen normally inhibits bone resorption by osteoclasts. Its decline after menopause leads to increased bone loss, making the condition a common health issue among elderly women, with higher fracture risk compared to men.
8. Matching Type:
Match the following disorders with their causes:
(a) Arthritis – (i) Autoimmune disorder
(b) Osteomalacia – (ii) Vitamin D deficiency
(c) Gout – (iii) Uric acid crystals
(d) Myasthenia gravis – (iv) Autoantibodies
1. (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)
2. (a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)
3. (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)
4. (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)
Explanation:
The correct answer is option 1. Arthritis is often autoimmune, osteomalacia arises from vitamin D deficiency, gout is due to uric acid crystals, and myasthenia gravis results from autoantibodies against neuromuscular junction receptors. Understanding these mechanisms is crucial for clinical differentiation and therapeutic targeting of skeletal and neuromuscular diseases.
9. Fill in the Blank:
__________ is the childhood skeletal disorder caused by vitamin D deficiency.
1. Osteoporosis
2. Arthritis
3. Rickets
4. Tetany
Explanation:
The correct answer is Rickets. It is seen in children with inadequate sunlight exposure or poor vitamin D intake. Bones become soft, weak, and deformed due to defective mineralization. Recognizing this condition early enables preventive measures, distinguishing it from osteomalacia which occurs in adults due to similar deficiency.
10. Choose the Correct Statements:
1. Gout is due to uric acid deposition.
2. Osteoporosis occurs mainly due to high estrogen levels.
3. Tetany arises from hypocalcemia.
4. Muscular dystrophy is genetic in nature.
Options:
(a) 1, 2 and 3
(b) 1, 3 and 4
(c) 2 and 3
(d) 1 and 2 only
Explanation:
The correct answer is option (b). Gout is indeed due to uric acid crystals. Tetany is linked with hypocalcemia, and muscular dystrophy is genetic. Osteoporosis occurs due to estrogen deficiency, not excess. Such differentiation helps in accurate diagnosis and targeted treatment of musculoskeletal disorders affecting patients in clinical practice.
Subtopic: Bones of Thorax and Shoulder Girdle
Floating Ribs: Ribs that do not connect to the sternum and are free at their anterior ends.
Acromion: Bony projection of scapula forming the highest point of the shoulder and connecting with the clavicle.
Scapula: Shoulder blade; a flat bone connecting the humerus with the clavicle and supporting upper limb movements.
Glenoid cavity: Shallow depression in scapula articulating with head of humerus to form shoulder joint.
Clavicle: Collarbone connecting scapula to sternum, supporting shoulder movements.
Humerus: Bone of upper arm connecting scapula to elbow joint.
Sternum: Breastbone in the middle of thorax to which most ribs attach.
Thorax: Part of the body enclosed by ribs, sternum, and vertebrae, protecting heart and lungs.
Rib cage: Bony structure made of ribs and sternum enclosing thoracic organs.
Articulation: Joint or connection between two bones allowing movement.
Shoulder girdle: Bones (scapula and clavicle) connecting upper limb to axial skeleton.
Lead Question (2020): Match the following columns and select the correct option :
Columns - I Columns - II
(a) Floating Ribs (i) Located between second and seventh ribs
(b) Acromion (ii) Head of the Humerus
(c) Scapula (iii) Clavicle
(d) Glenoid cavity (iv) Do not connect with the sternum
a-iii, b-ii, c-iv, d-i
a-iv, b-iii, c-i, d-ii
a-ii, b-iv, c-i, d-iii
a-i, b-iii, c-ii, d-iv
Explanation: The correct answer is 2. Floating ribs are those that do not connect to the sternum (a-iv). Acromion is the bony projection connecting with clavicle (b-iii). Scapula is located between second and seventh ribs (c-i). Glenoid cavity articulates with the head of humerus (d-ii), forming the shoulder joint.
Guessed MCQs:
Question 1: Which rib is called a floating rib?
A. First rib
B. Last two ribs
C. Third rib
D. All true ribs
Explanation: The correct answer is B. The 11th and 12th ribs are floating ribs as they do not attach anteriorly to the sternum, providing flexibility and protection without direct sternum articulation.
Question 2: Acromion connects with:
A. Humerus
B. Scapula
C. Clavicle
D. Sternum
Explanation: The correct answer is C. Acromion is a bony projection of scapula that articulates with the clavicle, forming the acromioclavicular joint essential for shoulder movement.
Question 3: Glenoid cavity articulates with:
A. Radius
B. Ulna
C. Humerus
D. Clavicle
Explanation: The correct answer is C. Glenoid cavity of scapula forms the socket for the head of humerus, allowing ball-and-socket movement at the shoulder joint.
Question 4: Scapula is located:
A. Between first and fifth ribs
B. Between second and seventh ribs
C. Behind sternum
D. On clavicle
Explanation: The correct answer is B. The scapula is a flat bone situated on the posterior thoracic wall between second and seventh ribs, providing attachment for muscles and articulation with humerus.
Question 5: Floating ribs are different from true ribs because:
A. They are longer
B. They lack anterior attachment to sternum
C. They are fused
D. They are part of scapula
Explanation: The correct answer is B. Floating ribs (11th and 12th) do not connect to the sternum anteriorly, unlike true ribs which attach directly to the sternum.
Question 6: Clavicle connects:
A. Sternum to humerus
B. Sternum to scapula
C. Humerus to scapula
D. Scapula to ribs
Explanation: The correct answer is B. Clavicle or collarbone connects scapula to sternum, providing support and enabling shoulder mobility.
Question 7: Assertion-Reason:
Assertion (A): Floating ribs do not attach to sternum.
Reason (R): They articulate with vertebrae only.
A. Both A and R are true, R is correct explanation
B. Both A and R are true, R is not correct explanation
C. A true, R false
D. A false, R true
Explanation: The correct answer is A. Floating ribs are free anteriorly and attach only to vertebrae posteriorly, which explains why they do not connect with the sternum.
Question 8: Matching Type: Match bones with features:
i. Scapula - A. Articulates with humerus
ii. Clavicle - B. Connects scapula to sternum
iii. Floating rib - C. Does not connect to sternum
iv. Acromion - D. Bony projection connecting clavicle
Choices:
A. i-A, ii-B, iii-C, iv-D
B. i-B, ii-A, iii-D, iv-C
C. i-C, ii-D, iii-A, iv-B
D. i-D, ii-C, iii-B, iv-A
Explanation: The correct answer is A. Scapula articulates with humerus (i-A), clavicle connects scapula to sternum (ii-B), floating ribs do not connect to sternum (iii-C), and acromion is projection connecting clavicle (iv-D).
Question 9: Fill in the Blanks: The ________ cavity of scapula articulates with the head of humerus.
A. Acromion
B. Glenoid
C. Coracoid
D. Clavicular
Explanation: The correct answer is B. The glenoid cavity forms the socket of the shoulder joint, allowing articulation with the head of the humerus for wide range of movements.
Question 10: Choose the correct statements:
i. Floating ribs do not connect to sternum
ii. Acromion connects with clavicle
iii. Scapula lies between second and seventh ribs
iv. Glenoid cavity articulates with clavicle
A. i, ii, iii
B. ii, iii, iv
C. i, iii, iv
D. i, ii, iii, iv
Explanation: The correct answer is A. Floating ribs are free anteriorly (i), acromion articulates with clavicle (ii), scapula lies between second and seventh ribs (iii). Glenoid cavity articulates with humerus, not clavicle.
Topic: Thoracic Cage
Subtopic: Ribs and Sternum Articulation
Keyword Definitions:
• Vertebrosternal ribs: Ribs that attach directly to the sternum via costal cartilage.
• Vertebrochondral ribs: Ribs indirectly connected to the sternum through cartilage of superior ribs.
• Vertebral ribs: Ribs not connected to the sternum; also called floating ribs.
• Sternum: Flat bone forming the anterior midline of the thorax.
• Hyaline cartilage: Flexible cartilage present at the anterior ends of ribs for articulation.
• Thoracic vertebrae: 12 vertebrae forming the posterior attachment of ribs.
Lead Question (September 2019):
Select the correct option:
(1) 8th, 9th and 10th pairs of ribs articulate directly with the sternum.
(2) 11th and 12th pairs of ribs are connected to the sternum with the help of hyaline cartilage.
(3) Each rib is a flat thin bone and all the ribs are connected dorsally to the thoracic vertebrae and ventrally to the sternum.
(4) There are seven pairs of vertebrosternal, three pairs of vertebrochondral and two pairs of vertebral ribs.
Explanation: The correct answer is (4). The human thoracic cage has 12 pairs of ribs: 7 vertebrosternal, 3 vertebrochondral, and 2 vertebral ribs. Dorsally all ribs attach to thoracic vertebrae; anterior connection varies. NEET UG tests detailed knowledge of thoracic skeletal anatomy.
1) Which ribs are floating ribs?
(1) 1st and 2nd
(2) 11th and 12th
(3) 8th and 9th
(4) 5th and 6th
Explanation: The correct answer is (2) 11th and 12th pairs. Floating ribs are not connected anteriorly to the sternum. NEET UG evaluates understanding of thoracic cage rib classification.
2) How many vertebrochondral ribs are there?
(1) 2
(2) 3
(3) 7
(4) 5
Explanation: The correct answer is (2) 3. Vertebrochondral ribs (8th, 9th, 10th) attach indirectly to sternum through superior rib cartilage. NEET UG may ask rib articulation details.
3) Characteristics of ribs include:
(1) Flat and thin bones
(2) Connected dorsally to thoracic vertebrae
(3) Ventral attachment varies
(4) All of the above
Explanation: The correct answer is (4). Ribs are flat, thin, dorsally attached to thoracic vertebrae, ventral connection differs. NEET UG tests structural details of thoracic cage bones.
4) Vertebrosternal ribs are:
(1) 8th, 9th, 10th
(2) 11th, 12th
(3) 1st to 7th
(4) 2nd to 9th
Explanation: The correct answer is (3) 1st to 7th ribs. They connect directly to the sternum via costal cartilage. NEET UG may test classification of ribs by anterior attachment.
5) Hyaline cartilage is found in:
(1) Floating ribs
(2) Vertebrochondral ribs
(3) Vertebrosternal ribs
(4) All ribs
Explanation: The correct answer is (2). Vertebrochondral ribs use hyaline cartilage to attach indirectly to sternum. NEET UG tests knowledge of rib-sternum connections.
6) Dorsal attachment of ribs is always to:
(1) Lumbar vertebrae
(2) Thoracic vertebrae
(3) Sacrum
(4) Cervical vertebrae
Explanation: The correct answer is (2) Thoracic vertebrae. All ribs dorsally articulate with thoracic vertebrae. NEET UG tests skeletal anatomy of thorax.
7) Assertion-Reason Type:
Assertion (A): The 8th rib attaches indirectly to the sternum.
Reason (R): It is a vertebrochondral rib connecting via superior rib cartilage.
(1) A true, R true, R correct explanation
(2) A true, R true, R not explanation
(3) A true, R false
(4) A false, R true
Explanation: The correct answer is (1). The 8th rib is vertebrochondral and connects indirectly to sternum via cartilage. NEET UG tests correlation between rib type and attachment.
8) Matching Type:
Match rib type with characteristic:
(a) Vertebrosternal - (i) 1st to 7th, direct sternum
(b) Vertebrochondral - (ii) 8th to 10th, indirect sternum
(c) Vertebral ribs - (iii) 11th, 12th, no sternum
Options:
(1) a-i, b-ii, c-iii
(2) a-ii, b-i, c-iii
(3) a-iii, b-ii, c-i
(4) a-i, b-iii, c-ii
Explanation: The correct answer is (1). Vertebrosternal: 1–7, direct sternum; vertebrochondral: 8–10, indirect; vertebral: 11–12, floating. NEET UG tests classification of rib types.
9) Fill in the blanks:
The 11th and 12th pairs of ribs are called ______.
(1) Vertebrosternal
(2) Vertebrochondral
(3) Vertebral
(4) Floating
Explanation: The correct answer is (3) Vertebral ribs, also called floating ribs. NEET UG evaluates knowledge of rib classification and terminology.
10) Choose the correct statements:
(1) First 7 ribs are vertebrosternal
(2) 8th to 10th ribs are vertebrochondral
(3) 11th and 12th ribs are floating
(4) All ribs directly connect to sternum
Options:
(1) 1, 2, 3
(2) 1, 3, 4
(3) 2, 3, 4
(4) 1, 2, 4
Explanation: The correct answer is (1) 1, 2, 3. Only first 7 ribs attach directly; 8–10 indirectly; 11–12 floating. NEET UG examines rib classification and anterior attachment patterns.
Topic: Muscular Disorders
Subtopic: Inherited and Acquired Muscle Diseases
Keyword Definitions
Tetany: Condition due to low calcium levels causing muscle spasms.
Muscular dystrophy: Inherited disorder leading to progressive muscle weakness.
Myasthenia gravis: Autoimmune neuromuscular disease causing muscle fatigue.
Botulism: Paralytic disease caused by toxin from Clostridium botulinum.
Inherited disorder: Disease transmitted genetically from parents to offspring.
Lead Question - 2019
Which of the following muscular disorders is inherited?
(1) Tetany
(2) Muscular dystrophy
(3) Myasthenia gravis
(4) Botulism
Explanation: Muscular dystrophy is an inherited genetic disorder characterized by progressive weakness and degeneration of skeletal muscles. Unlike tetany, myasthenia gravis, or botulism which are acquired conditions, muscular dystrophy runs in families. The correct answer is (2) Muscular dystrophy. It is most commonly linked to defective dystrophin gene on the X chromosome.
1) Guessed Question
Duchenne muscular dystrophy is caused due to mutations in
(1) Dystrophin gene
(2) Actin gene
(3) Troponin gene
(4) Myosin gene
Explanation: Duchenne muscular dystrophy is the most severe form of muscular dystrophy, caused by mutations in the dystrophin gene located on the X chromosome. This protein provides structural stability to muscle fibers. Hence, the correct answer is (1) Dystrophin gene. Absence of dystrophin leads to progressive muscle degeneration and weakness.
2) Guessed Question
Myasthenia gravis occurs due to defect in
(1) Neuromuscular junction
(2) Sarcomere formation
(3) Calcium storage
(4) ATP synthesis
Explanation: Myasthenia gravis is an autoimmune disorder where antibodies block acetylcholine receptors at neuromuscular junctions. This prevents proper nerve impulse transmission to muscles, causing weakness and fatigue. The correct answer is (1) Neuromuscular junction. Treatment includes anticholinesterase drugs and immunosuppressive therapy to improve neuromuscular transmission.
3) Guessed Question
Botulism results from
(1) Autoimmune reaction
(2) Calcium deficiency
(3) Bacterial toxin
(4) Gene mutation
Explanation: Botulism is a rare but serious condition caused by toxins produced by the bacterium Clostridium botulinum. The toxin blocks acetylcholine release at synapses, leading to muscle paralysis. Thus, the correct answer is (3) Bacterial toxin. Proper food preservation prevents botulism outbreaks, especially in canned or fermented products.
4) Guessed Question
Tetany is caused due to
(1) Low magnesium
(2) Low calcium
(3) Low sodium
(4) High potassium
Explanation: Tetany occurs when blood calcium levels drop below normal, leading to increased excitability of nerves and involuntary muscle spasms. This condition may occur in hypoparathyroidism. Therefore, the correct answer is (2) Low calcium. Calcium plays a vital role in stabilizing nerve and muscle cell membranes, preventing hyperexcitability.
5) Guessed Question
Which muscular disorder is autoimmune in nature?
(1) Tetany
(2) Muscular dystrophy
(3) Myasthenia gravis
(4) Botulism
Explanation: Myasthenia gravis is an autoimmune disease caused by antibodies against acetylcholine receptors. This reduces signal transmission, leading to muscle weakness. The correct answer is (3) Myasthenia gravis. Unlike muscular dystrophy which is inherited, myasthenia gravis develops due to immune system malfunction targeting neuromuscular junction receptors.
6) Guessed Question
Which muscular disorder is caused by defective gene inheritance?
(1) Botulism
(2) Myasthenia gravis
(3) Tetany
(4) Muscular dystrophy
Explanation: Muscular dystrophy arises due to mutations in genes responsible for muscle protein structure, mainly dystrophin. This genetic defect is passed down from parents. Hence, the correct answer is (4) Muscular dystrophy. It highlights the hereditary nature of the disorder, differentiating it from acquired muscular diseases.
7) Assertion-Reason MCQ
Assertion: Muscular dystrophy is an inherited muscular disorder.
Reason: It occurs due to defective dystrophin gene.
(1) Both Assertion and Reason are true, and Reason is the correct explanation
(2) Both Assertion and Reason are true, but Reason is not the correct explanation
(3) Assertion is true but Reason is false
(4) Assertion is false but Reason is true
Explanation: Muscular dystrophy is indeed inherited, and the absence or mutation of dystrophin gene is the cause. Therefore, both assertion and reason are true, and the reason explains the assertion. The correct answer is (1). This shows the genetic basis of muscular dystrophy linked to defective dystrophin production.
8) Matching Type MCQ
Match the muscular disorder with its cause:
A. Tetany → 1. Low calcium
B. Muscular dystrophy → 2. Dystrophin gene mutation
C. Myasthenia gravis → 3. Autoimmune disease
D. Botulism → 4. Bacterial toxin
(1) A-1, B-2, C-3, D-4
(2) A-2, B-3, C-1, D-4
(3) A-3, B-1, C-4, D-2
(4) A-4, B-1, C-2, D-3
Explanation: Tetany is due to low calcium, muscular dystrophy due to dystrophin mutation, myasthenia gravis due to autoimmunity, and botulism due to bacterial toxin. Hence the correct answer is (1) A-1, B-2, C-3, D-4. This mapping illustrates the diverse origins of muscular disorders.
9) Fill in the Blanks MCQ
Duchenne muscular dystrophy is linked to the ______ chromosome.
(1) X
(2) Y
(3) 21st
(4) 18th
Explanation: Duchenne muscular dystrophy is inherited in an X-linked recessive pattern, affecting mostly males. The dystrophin gene responsible lies on the X chromosome. Hence, the correct answer is (1) X. Female carriers usually do not show severe symptoms, but they can pass the defective gene to offspring.
10) Choose the Correct Statements MCQ
Choose the correct statements regarding muscular disorders:
(a) Tetany is due to low calcium
(b) Muscular dystrophy is inherited
(c) Myasthenia gravis is autoimmune
(d) Botulism is genetic
(1) (a), (b), and (c)
(2) (b), (c), and (d)
(3) (a) and (d)
(4) (a) and (b)
Explanation: Tetany occurs due to low calcium, muscular dystrophy is inherited, and myasthenia gravis is autoimmune. Botulism, however, is caused by bacterial toxin, not genetics. Hence, the correct statements are (a), (b), and (c). Correct answer is (1). This highlights the differences between inherited and acquired muscular disorders.
Topic: Muscular System
Subtopic: Skeletal Muscle Contraction
Keyword Definitions:
• Calcium: A divalent cation essential for muscle contraction, neurotransmission, and bone structure.
• Skeletal muscle: Striated voluntary muscles attached to bones that enable movement.
• Troponin: Regulatory protein on actin filaments that binds calcium to initiate contraction.
• Actin: Thin filament protein in muscle fibers involved in contraction.
• Myosin: Thick filament motor protein responsible for sliding along actin during contraction.
• Cross-bridge: Interaction between myosin heads and actin filaments enabling contraction.
Lead Question - 2018
Calcium is important in skeletal muscle contraction because it :
(A) prevents the formation of bonds between the myosin cross bridges and the actin filament
(B) binds to troponin to remove the masking of active sites on actin for myosin
(C) detaches the myosin head from the actin filament
(D) activates the myosin ATPase by binding to it
Explanation:
Answer is (B). Calcium ions bind to troponin, inducing conformational changes that shift tropomyosin and expose active sites on actin. This exposure allows myosin cross bridges to attach to actin filaments, initiating skeletal muscle contraction. Without calcium, active sites remain masked, preventing contraction.
Guessed Questions for NEET UG:
1) Single Correct: Which ion triggers the release of neurotransmitters at the neuromuscular junction?
(A) Sodium
(B) Calcium
(C) Potassium
(D) Chloride
Explanation:
Answer is (B). Calcium influx into the presynaptic terminal triggers exocytosis of acetylcholine vesicles, enabling transmission of the nerve impulse to skeletal muscle fibers.
2) Single Correct: Tropomyosin in skeletal muscle:
(A) Binds calcium
(B) Covers active sites on actin
(C) Hydrolyzes ATP
(D) Forms cross bridges
Explanation:
Answer is (B). Tropomyosin blocks myosin-binding sites on actin in resting muscle. Calcium binding to troponin shifts tropomyosin, allowing cross-bridge formation and contraction.
3) Single Correct: During contraction, myosin heads:
(A) Remain stationary
(B) Attach and pull actin filaments
(C) Bind calcium
(D) Bind tropomyosin
Explanation:
Answer is (B). Myosin heads cyclically attach to actin, pivot, and pull thin filaments toward the sarcomere center, powered by ATP hydrolysis, producing muscle shortening.
4) Assertion-Reason:
Assertion: Calcium is essential for muscle contraction.
Reason: It binds to tropomyosin and moves it out of the way.
(A) Both true, Reason correct
(B) Both true, Reason incorrect
(C) Assertion true, Reason false
(D) Both false
Explanation:
Answer is (C). Calcium binds to troponin, not tropomyosin directly, which then moves tropomyosin to expose actin active sites, enabling myosin attachment and contraction.
5) Single Correct: Which protein directly interacts with calcium during contraction?
(A) Actin
(B) Myosin
(C) Troponin
(D) Tropomyosin
Explanation:
Answer is (C). Troponin binds calcium ions, causing conformational changes that shift tropomyosin and expose actin sites for myosin cross-bridge attachment.
6) Single Correct: ATP in skeletal muscle contraction:
(A) Binds actin
(B) Powers myosin head movement
(C) Binds calcium
(D) Binds troponin
Explanation:
Answer is (B). ATP binds myosin, hydrolysis provides energy for the power stroke, and detachment of myosin heads from actin, enabling repeated contraction cycles.
7) Matching Type:
Column I | Column II
a. Actin | i. Binds calcium
b. Troponin | ii. Thin filament
c. Myosin | iii. Thick filament
(A) a-ii, b-i, c-iii
(B) a-iii, b-i, c-ii
(C) a-i, b-iii, c-ii
(D) a-ii, b-iii, c-i
Explanation:
Answer is (A). Actin: thin filament (ii), Troponin: binds calcium (i), Myosin: thick filament (iii). Proper protein interactions are essential for contraction.
8) Fill in the Blank:
Calcium binds to ________ to initiate skeletal muscle contraction.
(A) Tropomyosin
(B) Troponin
(C) Actin
(D) Myosin
Explanation:
Answer is (B). Troponin binding with calcium causes tropomyosin movement, exposing actin active sites for myosin attachment and triggering contraction.
9) Choose the correct statements:
(i) Calcium ions are stored in the sarcoplasmic reticulum.
(ii) Calcium binding to troponin exposes actin sites.
(iii) Calcium directly hydrolyzes ATP.
(A) i and ii only
(B) ii and iii only
(C) i and iii only
(D) i, ii, iii
Explanation:
Answer is (A). Calcium is stored in the sarcoplasmic reticulum and binds troponin to expose actin. It does not hydrolyze ATP directly; ATP hydrolysis occurs at myosin heads.
10) Clinical-type: A patient has hypocalcemia. Which effect is expected in skeletal muscles?
(A) Enhanced contraction
(B) Reduced contraction
(C) No effect
(D) Continuous contraction
Explanation:
Answer is (B). Low calcium reduces binding to troponin, preventing tropomyosin movement. Consequently, actin sites remain masked, and skeletal muscle contraction is impaired, causing weakness or tetany.
Subtopic: Skeletal System - Joints
Keyword Definitions:
Pivot Joint: Synovial joint allowing rotational movement around a single axis.
Atlas: First cervical vertebra supporting the skull.
Axis: Second cervical vertebra with odontoid process enabling rotation.
Saddle Joint: Synovial joint allowing movement in two planes.
Fibrous Joint: Joint connected by fibrous tissue, mostly immovable.
Cartilaginous Joint: Joint connected by cartilage with limited movement.
Synovial Joint: Freely movable joint with synovial fluid.
Odontoid Process: Projection of axis around which atlas rotates.
Rotational Movement: Movement around a central axis.
Clinical Significance: Injuries to atlanto-axial joint can impair head rotation and cause neurological issues.
Joint Disorders: Conditions like arthritis or dislocation can affect mobility and stability.
Lead Question - 2017
The pivot joint between atlas and axis is a type of:
(A) saddle joint
(B) Fibrous joint
(C) Cartilaginous joint
(D) Synovial joint
Explanation: The joint between atlas and axis is a pivot synovial joint allowing rotational movement of the head. Atlas rotates around the odontoid process of axis. It is freely movable, making it a synovial joint, not fibrous, cartilaginous, or saddle. Correct answer: D.
1. MCQ - Single Correct Answer
Which movement is allowed by the atlanto-axial joint?
(a) Flexion only
(b) Rotation of head
(c) Abduction
(d) Extension only
Explanation: The pivot joint between atlas and axis permits rotation of the head on a vertical axis. Flexion, extension, or abduction are limited at this joint. This rotation allows shaking the head side to side. Correct answer: b.
2. MCQ - Single Correct Answer
The odontoid process is part of which vertebra?
(a) Atlas
(b) Axis
(c) Cervical 3
(d) Thoracic 1
Explanation: The odontoid process, or dens, is a projection of the axis (C2) vertebra. The atlas rotates around it, forming a pivot joint. Atlas is C1 without dens, cervical 3 and thoracic vertebrae are not involved in pivot rotation. Correct answer: b.
3. MCQ - Single Correct Answer (Clinical)
Fracture of the odontoid process affects:
(a) Shoulder rotation
(b) Head rotation
(c) Wrist movement
(d) Knee extension
Explanation: A fracture of the odontoid process disrupts the pivot joint, impairing head rotation. It can lead to spinal cord injury with neurological deficits. Shoulder, wrist, or knee movement is not directly affected. Correct answer: b.
4. MCQ - Single Correct Answer
Which type of synovial joint is the atlanto-axial joint?
(a) Ball and socket
(b) Hinge
(c) Pivot
(d) Saddle
Explanation: The atlanto-axial joint is a pivot synovial joint, allowing rotation around a single axis. Ball and socket allow multi-directional movement, hinge allows flexion-extension, and saddle permits movement in two planes. Correct answer: c.
5. MCQ - Single Correct Answer
Atlas articulates superiorly with:
(a) Occipital condyles
(b) Axis
(c) Thoracic vertebrae
(d) Sacrum
Explanation: The atlas (C1) articulates superiorly with occipital condyles of the skull, allowing nodding movements. Inferiorly, it articulates with axis for rotation. Thoracic vertebrae and sacrum are unrelated to this joint. Correct answer: a.
6. MCQ - Single Correct Answer (Clinical)
Atlanto-axial subluxation is commonly associated with which condition?
(a) Osteoporosis
(b) Rheumatoid arthritis
(c) Hip dysplasia
(d) Scoliosis
Explanation: Rheumatoid arthritis can affect ligaments of the atlanto-axial joint, leading to subluxation and risk of spinal cord compression. Osteoporosis affects bones generally, hip dysplasia affects hip joint, scoliosis affects spinal curvature. Correct answer: b.
7. MCQ - Assertion-Reason
Assertion (A): Atlanto-axial joint is a pivot joint.
Reason (R): It allows rotational movement of the head.
(a) Both A and R true, R correct explanation
(b) Both A and R true, R not correct explanation
(c) A true, R false
(d) A false, R true
Explanation: The atlanto-axial joint is indeed a pivot joint, allowing rotation of the head around the odontoid process. Both assertion and reason are true, and the reason correctly explains the assertion. Correct answer: a.
8. MCQ - Matching Type
Match joint type with example:
1. Pivot - (a) Elbow
2. Hinge - (b) Atlanto-axial
3. Ball and socket - (c) Shoulder
Options:
(A) 1-b, 2-a, 3-c
(B) 1-a, 2-b, 3-c
(C) 1-c, 2-a, 3-b
(D) 1-b, 2-c, 3-a
Explanation: Pivot joint: atlanto-axial; Hinge: elbow; Ball and socket: shoulder. Correct matching: 1-b, 2-a, 3-c. Answer: A.
9. MCQ - Fill in the Blanks
The atlas rotates around the __________ of axis.
(a) Odontoid process
(b) Spinous process
(c) Transverse process
(d) Vertebral body
Explanation: The atlas rotates around the odontoid process (dens) of axis, forming a pivot joint. This allows lateral rotation of the head. Spinous and transverse processes or vertebral body are not rotation points. Correct answer: a.
10. MCQ - Choose Correct Statements
Select correct statements about atlanto-axial joint:
1. Pivot synovial joint
2. Allows head rotation
3. Located between atlas and axis
4. Limited movement in all directions
Options:
(A) 1, 2, and 3
(B) 1 and 4
(C) 2 and 3 only
(D) All 1,2,3,4
Explanation: The atlanto-axial joint is a pivot synovial joint, located between atlas and axis, permitting head rotation. It does not allow multi-directional movement. Correct statements: 1, 2, and 3. Answer: A.
Topic: Skeletal System
Subtopic: Ribs and Sternum
Keyword Definitions:
• Ribs – Curved bones forming the thoracic cage, protecting thoracic organs.
• True ribs – Ribs that attach directly to the sternum via costal cartilage.
• False ribs – Ribs indirectly attached or not attached to sternum.
• Floating ribs – Last two pairs of ribs not attached ventrally.
• Vertebral column – Spine providing dorsal attachment for ribs.
• Sternum – Breastbone where true ribs attach ventrally.
• Thoracic cage – Skeleton of thorax including ribs, sternum, vertebrae.
• Costal cartilage – Hyaline cartilage connecting ribs to sternum.
• Dorsal – Back side of the body.
• Ventral – Front side of the body.
Lead Question – 2017:
Out of ‘X’ pairs of ribs in humans only ‘Y’ pairs are true ribs. Select the option that correctly represents values of X and Y and provides their explanation:
(A) X = 24, Y = 12 True ribs are dorsally attached to vertebral column but are free on ventral side
(B) X = 12, Y = 7 True ribs are attached dorsally to vertebral column and ventrally to the sternum
(C) X = 12, Y = 5 True ribs are attached dorsally to vertebral column and sternum on the two ends
(D) X = 24, Y = 7 True ribs are dorsally attached to vertebral column but are free on ventral side
Explanation:
Humans have 12 pairs of ribs (X = 12), of which the first seven pairs (Y = 7) are true ribs that attach dorsally to vertebrae and ventrally to the sternum through costal cartilage. The remaining five pairs are false or floating ribs. Hence, correct answer is (B). (Answer: B)
1) Single Correct Answer MCQ:
Which ribs are called floating ribs?
(A) 1st and 2nd pairs
(B) 11th and 12th pairs
(C) 7th pair
(D) 5th and 6th pairs
Explanation:
Floating ribs (11th and 12th pairs) are not attached ventrally to the sternum, providing protection to lower organs but allowing flexibility. (Answer: B)
2) Single Correct Answer MCQ:
Costal cartilage connects ribs to:
(A) Vertebrae
(B) Sternum
(C) Scapula
(D) Clavicle
Explanation:
True ribs connect to the sternum ventrally through costal cartilage, while dorsally they attach to vertebrae. (Answer: B)
3) Single Correct Answer MCQ:
Which statement is correct regarding false ribs?
(A) Attach directly to sternum
(B) Attach indirectly or not at all to sternum
(C) Always float freely
(D) None of the above
Explanation:
False ribs (8th–12th pairs) are indirectly attached or free ventrally, with the last two pairs being floating ribs. (Answer: B)
4) Single Correct Answer MCQ:
Total number of ribs in a human adult is:
(A) 24
(B) 12
(C) 14
(D) 20
Explanation:
Humans have 12 pairs of ribs, totaling 24 individual ribs forming the thoracic cage. (Answer: A)
5) Single Correct Answer MCQ:
True ribs are also called:
(A) Vertebral ribs
(B) Sternal ribs
(C) Floating ribs
(D) False ribs
Explanation:
True ribs are sternal ribs as they attach directly to the sternum via costal cartilage. (Answer: B)
6) Single Correct Answer MCQ:
Which rib pair is attached dorsally to vertebrae but ventrally free?
(A) 1st pair
(B) 7th pair
(C) 11th pair
(D) 5th pair
Explanation:
Floating ribs (11th pair) are dorsally attached to vertebrae but ventrally free, allowing movement and protection of lower abdominal organs. (Answer: C)
7) Assertion-Reason MCQ:
Assertion (A): True ribs are attached to both vertebrae and sternum.
Reason (R): True ribs support and protect thoracic organs.
(A) Both A and R true, R explains A
(B) Both A and R true, R does not explain A
(C) A true, R false
(D) A false, R true
Explanation:
Both A and R are correct. True ribs are connected dorsally and ventrally, providing protection to heart and lungs. (Answer: A)
8) Matching Type MCQ:
Match:
1. True ribs – (i) Direct attachment to sternum
2. False ribs – (ii) Indirect or no attachment
3. Floating ribs – (iii) Last two pairs
Options:
(A) 1-i, 2-ii, 3-iii
(B) 1-ii, 2-i, 3-iii
(C) 1-i, 2-iii, 3-ii
(D) 1-iii, 2-i, 3-ii
Explanation:
Correct matching: 1-i (true ribs attach directly), 2-ii (false ribs indirect/no), 3-iii (floating ribs are last two pairs). (Answer: A)
9) Fill in the Blanks MCQ:
The thoracic cage consists of ______ pairs of ribs.
(A) 10
(B) 12
(C) 14
(D) 7
Explanation:
The human thoracic cage has 12 pairs of ribs, forming a protective cage for thoracic organs. (Answer: B)
10) Choose the correct statements MCQ:
1. True ribs are 1–7 pairs
2. False ribs are 8–12 pairs
3. Floating ribs are part of true ribs
4. All ribs attach to sternum ventrally
Options:
(A) 1, 2
(B) 1, 3
(C) 2, 4
(D) 1, 4
Explanation:
Statements 1 and 2 are correct. Floating ribs are not part of true ribs, and not all ribs attach to sternum. True ribs are 1–7; false ribs 8–12, with 11th–12th floating. (Answer: A)
Topic: Locomotion and Movement
Subtopic: Skeletal Disorders
Keyword Definitions:
Osteoporosis: A skeletal disorder marked by low bone mass and fragile bones.
Estrogen: A hormone essential for bone health; its deficiency accelerates bone loss.
Uric Acid: Waste product; excess causes gout, not osteoporosis.
Neuromuscular Junction: Site where nerves communicate with muscles.
Calcium Ions (Ca++): Vital for bone mineralization and muscle contraction.
Skeletal System: Framework of bones providing support, protection, and movement.
Lead Question - 2016 (Phase 2)
Osteoporosis, an age- related disease of skeletal system, may occur due to :
(1) accumulation of uric acid leading to inflammation of joints
(2) immune disorder affecting neuromuscular junction leading to fatigue
(3) high concentration of Ca++ and Na+
(4) decreased level of estrogen
Explanation: Osteoporosis is characterized by fragile bones due to reduced bone mass. It often occurs in postmenopausal women because estrogen levels drop, reducing calcium deposition in bones. Correct answer is (4) decreased level of estrogen. Estrogen maintains bone density, and its deficiency accelerates bone resorption leading to osteoporosis.
1. A 65-year-old woman presents with frequent fractures after minor falls. Which hormone deficiency is most likely responsible?
(1) Estrogen
(2) Progesterone
(3) Cortisol
(4) Testosterone
Explanation: Postmenopausal women often develop osteoporosis due to estrogen deficiency, leading to weak bones and increased fracture risk. Correct answer is (1) Estrogen. Progesterone and testosterone have limited skeletal roles, while cortisol excess leads to osteoporosis but not in typical age-related cases.
2. Which vitamin is most essential for intestinal absorption of calcium?
(1) Vitamin A
(2) Vitamin D
(3) Vitamin K
(4) Vitamin E
Explanation: Vitamin D promotes intestinal absorption of calcium and phosphate, essential for bone mineralization. Its deficiency causes rickets in children and osteomalacia in adults. Correct answer is (2) Vitamin D. Vitamin A and K help bone remodeling, but absorption depends on Vitamin D.
3. Which bone cells are responsible for bone resorption in osteoporosis?
(1) Osteoblasts
(2) Osteoclasts
(3) Chondrocytes
(4) Fibroblasts
Explanation: Osteoclasts are bone-resorbing cells that break down bone tissue. In osteoporosis, osteoclastic activity exceeds osteoblastic formation, leading to reduced bone density. Correct answer is (2) Osteoclasts. Osteoblasts form bone, while chondrocytes and fibroblasts serve other functions.
4. Assertion-Reason: Assertion: Osteoporosis risk increases in postmenopausal women. Reason: Decreased estrogen enhances osteoclastic activity.
(1) Both A and R true, R explains A
(2) Both A and R true, R not explanation
(3) A true, R false
(4) A false, R true
Explanation: Estrogen deficiency in menopause leads to enhanced osteoclastic activity, weakening bones and increasing fracture risk. Correct answer is (1) Both A and R are true, and R explains A. Hence, estrogen directly maintains bone density by suppressing resorption.
5. A patient with osteoporosis is given bisphosphonates. These drugs primarily act by:
(1) Inhibiting osteoblast activity
(2) Stimulating calcium absorption
(3) Inhibiting osteoclast activity
(4) Increasing vitamin D levels
Explanation: Bisphosphonates inhibit osteoclast activity, reducing bone resorption and slowing bone loss in osteoporosis patients. Correct answer is (3) Inhibiting osteoclast activity. They do not directly affect osteoblasts, vitamin D, or absorption, but indirectly improve bone mineral density.
6. Which of the following is a clinical feature of osteoporosis?
(1) Bone pain and fractures
(2) Muscle cramps
(3) Swollen joints
(4) Nerve palsy
Explanation: Osteoporosis typically presents with bone pain, fractures after minor trauma, and spinal deformities like kyphosis. Correct answer is (1) Bone pain and fractures. Muscle cramps are due to electrolyte imbalance, swollen joints suggest arthritis, and nerve palsy is neurological.
7. Matching Type: Match the hormone with its role in bone health:
A. Estrogen
B. Parathyroid hormone
C. Calcitonin
D. Vitamin D
(i) Increases calcium absorption
(ii) Inhibits osteoclasts
(iii) Promotes bone resorption
(iv) Maintains bone density
(1) A-iv, B-iii, C-ii, D-i
(2) A-ii, B-i, C-iv, D-iii
(3) A-iii, B-iv, C-i, D-ii
(4) A-iv, B-ii, C-iii, D-i
Explanation: Estrogen maintains bone density, PTH promotes bone resorption, Calcitonin inhibits osteoclasts, and Vitamin D increases calcium absorption. Correct answer is (1) A-iv, B-iii, C-ii, D-i. Together, they regulate calcium balance and bone homeostasis.
8. Fill in the Blank: __________ deficiency accelerates osteoporosis in elderly women.
(1) Testosterone
(2) Estrogen
(3) Progesterone
(4) Thyroxine
Explanation: Estrogen deficiency after menopause accelerates bone resorption, increasing the risk of osteoporosis in women. Correct answer is (2) Estrogen. Testosterone, progesterone, and thyroxine play secondary roles but estrogen is the critical hormone for skeletal health in females.
9. Which diagnostic test is most commonly used to detect osteoporosis?
(1) X-ray
(2) DEXA scan
(3) MRI
(4) Ultrasound
Explanation: DEXA (Dual Energy X-ray Absorptiometry) scan is the gold standard for measuring bone mineral density and diagnosing osteoporosis. Correct answer is (2) DEXA scan. X-rays detect only advanced cases, while MRI and ultrasound are not standard diagnostic methods for osteoporosis.
10. Choose the correct statements about osteoporosis:
(1) It causes weak and brittle bones
(2) Estrogen deficiency increases risk
(3) Calcium and Vitamin D supplementation helps
(4) Uric acid accumulation is the cause
(A) 1, 2, 3 only
(B) 2, 3, 4 only
(C) 1 and 4 only
(D) All four
Explanation: Osteoporosis causes weak bones, worsened by estrogen deficiency. Calcium and Vitamin D supplementation reduces risk. Uric acid accumulation causes gout, not osteoporosis. Correct answer is (A) 1, 2, 3 only. Thus, lifestyle modification and early detection are crucial for prevention.
Topic : Muscle Contraction
Subtopic : Role of Calcium in Cross-Bridge Formation
Keyword Definitions :
Actin : Thin filament protein in muscle fibers that interacts with myosin for contraction.
Myosin : Thick filament protein with heads that bind actin to form cross-bridges during contraction.
Tropomyosin : Regulatory protein that blocks active sites on actin in a relaxed muscle.
Troponin : Protein complex that binds calcium, shifting tropomyosin to expose actin binding sites.
Calcium Ion (Ca²⁺) : Ion that initiates muscle contraction by unmasking active sites on actin filaments.
Lead Question - 2016 (Phase 2)
Name the ion responsible for unmasking of active sites for myosin for cross-bridge activity during muscle contraction :
(1) Potassium
(2) Calcium
(3) Magnesium
(4) Sodium
Explanation : Calcium ions bind to troponin, causing a conformational shift that moves tropomyosin away from actin’s active sites. This unmasking allows myosin heads to form cross-bridges with actin filaments. Thus, the correct answer is (2) Calcium, crucial for excitation-contraction coupling in skeletal muscle physiology.
1. Which molecule directly provides energy for cross-bridge cycling during muscle contraction?
(1) ATP
(2) ADP
(3) Creatine phosphate
(4) Glucose
Explanation : ATP is the immediate source of energy for cross-bridge cycling. Hydrolysis of ATP energizes myosin heads, enabling attachment, power stroke, and detachment from actin filaments. Hence, the correct answer is (1) ATP, making it essential for repeated muscle contractions and relaxation.
2. Clinical Case: A patient with severe muscle weakness is suspected of myasthenia gravis. This condition is caused by autoantibodies against:
(1) Actin
(2) Acetylcholine receptors
(3) Troponin
(4) Myosin
Explanation : Myasthenia gravis is an autoimmune disorder where antibodies block or destroy acetylcholine receptors at the neuromuscular junction. This prevents efficient transmission of nerve impulses to muscles. Therefore, the correct answer is (2) Acetylcholine receptors, leading to progressive weakness and fatigue.
3. Which structure stores calcium ions in skeletal muscle fibers?
(1) Golgi apparatus
(2) Sarcoplasmic reticulum
(3) Mitochondria
(4) Lysosomes
Explanation : The sarcoplasmic reticulum serves as the calcium storage organelle in muscle fibers. Upon stimulation, it releases calcium ions into the cytoplasm to initiate contraction. Hence, the correct answer is (2) Sarcoplasmic reticulum, essential for rapid contraction and relaxation cycles in muscles.
4. During the power stroke of muscle contraction, which event occurs?
(1) Myosin head binds ATP
(2) Myosin head pulls actin filament inward
(3) Calcium is pumped back into the sarcoplasmic reticulum
(4) Troponin detaches from actin
Explanation : During the power stroke, the energized myosin head pivots and pulls the actin filament toward the center of the sarcomere, generating force. This step shortens the muscle fiber. Thus, the correct answer is (2) Myosin head pulls actin filament inward.
5. Assertion (A): Rigor mortis occurs after death due to lack of ATP.
Reason (R): ATP is required for detachment of myosin heads from actin filaments.
(1) Both A and R are true, R is correct explanation of A
(2) Both A and R are true, R is not correct explanation of A
(3) A is true, R is false
(4) A is false, R is true
Explanation : After death, ATP production ceases. Without ATP, myosin heads remain bound to actin, leading to rigidity known as rigor mortis. Thus, both A and R are true, and R correctly explains A. The correct answer is (1).
6. Match the muscle structure in Column I with its function in Column II:
a. Actin - i. Thick filament
b. Myosin - ii. Thin filament
c. Sarcomere - iii. Functional unit of contraction
d. Tropomyosin - iv. Blocks actin binding sites
(1) a-ii, b-i, c-iii, d-iv
(2) a-i, b-ii, c-iv, d-iii
(3) a-iii, b-iv, c-ii, d-i
(4) a-iv, b-iii, c-i, d-ii
Explanation : Actin forms the thin filament, myosin forms the thick filament, sarcomere is the functional unit of contraction, and tropomyosin blocks actin sites in resting muscles. Hence, the correct match is (1) a-ii, b-i, c-iii, d-iv, ensuring proper contraction regulation.
7. Fill in the Blank: The neurotransmitter released at the neuromuscular junction is ______.
(1) Dopamine
(2) Acetylcholine
(3) Serotonin
(4) Noradrenaline
Explanation : Acetylcholine is released by motor neurons at neuromuscular junctions. It binds to receptors on the muscle fiber, triggering depolarization and subsequent contraction. Therefore, the correct answer is (2) Acetylcholine, a vital neurotransmitter for skeletal muscle activation.
8. Choose the correct statements:
A. Calcium ions are stored in the sarcoplasmic reticulum.
B. Myosin heads require ATP for detachment.
C. Tropomyosin exposes actin binding sites when bound to calcium.
D. Actin is a thick filament.
(1) A, B, and C
(2) A and D
(3) B and C only
(4) A, C, and D
Explanation : Statements A and B are correct. Calcium is stored in the sarcoplasmic reticulum, and ATP is required for detachment of myosin. However, it is troponin, not tropomyosin, that binds calcium. Actin is thin, not thick. Thus, the correct answer is (1).
Chapter: Animal Physiology
Topic: Locomotion and Movement
Subtopic: Biomechanics of Animal Movement
Keyword Definitions:
Metabolic Rate: The rate at which an organism converts energy from food into usable energy for cellular processes.
Oxygen Requirement: The amount of oxygen an organism needs to sustain its metabolic activities.
Muscle Efficiency: The ability of muscles to convert chemical energy into mechanical work during movement.
Body Weight: The mass of an animal which affects the energy required for movement.
Uphill Locomotion: Movement against gravity, typically requiring more energy in large animals.
2016 (Phase 1)
Lead Question: It is much easier for a small animal to run uphill than for a large animal, because:
(1) It is easier to carry a small body weight.
(2) Smaller animals have a higher metabolic rate.
(3) Small animals have a lower O2 requirement.
(4) The efficiency of muscles in large animals is less than in small animals.
Answer & Explanation: The correct answer is (1). Small animals have lower body mass, requiring less energy to overcome gravity when running uphill. This makes uphill movement energetically more efficient for small animals than for large ones, which have higher body weight and energy requirements, making uphill locomotion more difficult and demanding for them.
Single Correct Answer MCQ: Which of the following is a major factor making uphill movement easier for small animals?
(1) Low oxygen consumption
(2) Higher metabolic rate
(3) Lower body weight
(4) Higher muscle efficiency
Answer & Explanation: The correct answer is (3). Small animals have lower body weight, which reduces the energy needed to lift themselves uphill. Energy cost of locomotion depends significantly on body weight, making small animals more efficient during uphill movement. Metabolic rate or muscle efficiency plays a lesser role compared to body mass in this context.
Assertion-Reason MCQ:
Assertion (A): Small animals can run uphill more easily than large animals.
Reason (R): Small body weight reduces the energy needed for uphill locomotion.
(1) Both A and R are true, and R is correct explanation of A.
(2) Both A and R are true, but R is not correct explanation of A.
(3) A is true, but R is false.
(4) A is false, but R is true.
Answer & Explanation: The correct answer is (1). The small body weight of small animals reduces the energy required to overcome gravity when moving uphill. This makes uphill locomotion easier compared to large animals whose greater mass requires significantly more energy for the same movement.
Matching Type MCQ: Match Term to Definition:
A. Metabolic rate 1. Energy use per unit time
B. Muscle efficiency 2. Conversion of chemical to mechanical energy
C. Body weight 3. Mass of an animal
D. Oxygen requirement 4. Oxygen needed for metabolism
(1) A-1, B-2, C-3, D-4
(2) A-4, B-3, C-2, D-1
(3) A-2, B-1, C-4, D-3
(4) A-3, B-4, C-1, D-2
Answer & Explanation: The correct answer is (1). Metabolic rate refers to energy use per unit time. Muscle efficiency refers to conversion of chemical energy into mechanical work. Body weight indicates the mass of the animal. Oxygen requirement refers to the oxygen needed to sustain metabolism during activity.
Fill in the Blanks / Completion MCQ: The primary reason small animals run uphill more easily is their __________.
(1) higher metabolic rate
(2) lower body weight
(3) better muscle efficiency
(4) lower oxygen requirement
Answer & Explanation: The correct answer is (2). Small animals have lower body weight compared to large animals. This reduces the energy cost to overcome gravity when moving uphill, making them more efficient. Other factors like metabolic rate or oxygen requirement play a secondary role in this specific context.
Choose the correct statements MCQ:
1. Small animals require less energy for uphill movement.
2. Large animals have higher muscle efficiency.
3. Metabolic rate has no role in uphill locomotion.
4. Oxygen requirement depends on body size.
(1) 1 and 4 only
(2) 2 and 3 only
(3) 1, 3, and 4 only
(4) 1, 2, and 4 only
Answer & Explanation: The correct answer is (1). Small animals need less energy for uphill movement due to lower body weight. Oxygen requirement scales with body size. Muscle efficiency does not significantly differ in this context, and metabolic rate has a role but is not the main reason.
Keywords:
Muscle contraction: Shortening of muscle fibers resulting in movement.
Sustained contraction: Continuous contraction over a period of time.
Spasm: Involuntary, sudden muscle contraction.
Fatigue: Temporary decline in muscle performance due to prolonged activity.
Tetanus: Continuous, sustained contraction of muscles without relaxation between stimuli.
Tonus: Continuous partial contraction of muscles at rest.
Stimulus: A signal triggering muscle contraction.
Neuromuscular junction: Connection between motor neuron and muscle fiber.
Calcium ions: Ions responsible for muscle contraction by interacting with troponin-tropomyosin complex.
ATP: Energy source required for muscle contraction and relaxation.
Myosin-actin interaction: Molecular mechanism underlying muscle contraction.
Chapter: Muscle Physiology
Topic: Muscle Contraction
Subtopic: Types of Muscle Contraction
Lead Question - 2016 (Phase 1): Lack of relaxation between successive stimuli in sustained muscle contraction is known as :
(1) Spasm
(2) Fatigue
(3) Tetanus
(4) Tonus
Answer: 3
Explanation: Tetanus refers to continuous muscle contraction without relaxation due to repeated stimuli. Unlike spasm or tonus, tetanus results from rapid stimuli summating the muscle response. This is physiologically important for sustained actions but may cause cramping in clinical conditions.
1. Single Correct Answer MCQ: Which ion triggers muscle contraction?
(A) Sodium
(B) Potassium
(C) Calcium
(D) Chloride
Answer: C
Explanation: Calcium ions are released from the sarcoplasmic reticulum and bind to troponin, initiating actin-myosin interaction and muscle contraction. Sodium and potassium mainly propagate action potentials, not directly trigger contraction.
2. Single Correct Answer MCQ: Fatigue in muscles occurs due to:
(A) Excess ATP
(B) Lactic acid accumulation
(C) High calcium concentration
(D) Continuous tetanus
Answer: B
Explanation: Muscle fatigue occurs due to lactic acid accumulation, depletion of energy stores, and ionic imbalances. This leads to reduced force production and temporary inability of muscles to sustain contraction.
3. Single Correct Answer MCQ: Partial continuous contraction in resting muscles is called:
(A) Spasm
(B) Tonus
(C) Tetanus
(D) Fatigue
Answer: B
Explanation: Muscle tonus is a low-level, continuous contraction present in resting muscles, maintaining posture and readiness for action. It differs from tetanus or spasm.
4. Single Correct Answer MCQ: A sudden involuntary muscle contraction is termed:
(A) Fatigue
(B) Tetanus
(C) Spasm
(D) Tonus
Answer: C
Explanation: Spasm is an involuntary, brief, sudden contraction of muscles. It may occur due to electrolyte imbalance, nerve irritation, or injury.
5. Single Correct Answer MCQ: Energy for muscle contraction is primarily supplied by:
(A) DNA
(B) ATP
(C) RNA
(D) Glucose only
Answer: B
Explanation: ATP is the direct energy source for actin-myosin cross-bridge cycling. Glucose and other substrates generate ATP via metabolism, but ATP is the immediate energy currency for contraction and relaxation.
6. Single Correct Answer MCQ: Summation of muscle contractions leading to sustained tension is called:
(A) Tetanus
(B) Fatigue
(C) Tonus
(D) Spasm
Answer: A
Explanation: Tetanus occurs when multiple stimuli rapidly follow one another, producing a sustained contraction without relaxation. This demonstrates temporal summation of muscle action potentials.
7. Assertion-Reason MCQ:
Assertion (A): Tetanus is continuous muscle contraction without relaxation.
Reason (R): Rapid successive stimuli prevent muscle fiber from relaxing completely.
(A) Both A and R are true, R is correct explanation of A
(B) Both A and R are true, R is NOT correct explanation of A
(C) A is true, R is false
(D) A is false, R is true
Answer: A
Explanation: Tetanus occurs when high-frequency stimuli summate, preventing relaxation. This leads to sustained maximal contraction, which is physiologically used for prolonged muscular activities.
8. Matching Type MCQ: Match type of contraction with description:
1. Spasm A. Partial contraction at rest
2. Tonus B. Involuntary sudden contraction
3. Tetanus C. Sustained contraction without relaxation
4. Fatigue D. Reduced ability to contract after prolonged activity
(A) 1-B, 2-A, 3-C, 4-D
(B) 1-A, 2-B, 3-D, 4-C
(C) 1-C, 2-D, 3-B, 4-A
(D) 1-D, 2-C, 3-B, 4-A
Answer: A
Explanation: Spasm is sudden contraction, tonus is partial contraction at rest, tetanus is sustained contraction, and fatigue reduces force after prolonged activity.
9. Fill in the Blanks: Continuous contraction without relaxation is called ________, while reduced muscle force after prolonged activity is termed ________.
(A) Tetanus; Fatigue
(B) Tonus; Spasm
(C) Spasm; Tetanus
(D) Fatigue; Tetanus
Answer: A
Explanation: Tetanus is sustained contraction due to repeated stimuli. Fatigue is the decline in muscle force after prolonged activity, often due to metabolic byproducts and energy depletion.
10. Choose the Correct Statements:
(A) Tetanus results from rapid successive stimuli.
(B) Spasm is involuntary muscle contraction.
(C) Fatigue is a sustained contraction without relaxation.
(D) Tonus maintains posture at rest.
(1) A, B, D
(2) A, C
(3) B, C
(4) All are correct
Answer: 1
Explanation: Statements A, B, and D are correct. Fatigue is not sustained contraction; it refers to decreased force after prolonged activity. Tetanus, not fatigue, is sustained contraction.