Animal Kingdom

Topic: General Characteristics of Chordates; Subtopic: Anatomical Features

Keyword Definitions:

• Chordates: Animals possessing a notochord, dorsal hollow nerve cord, pharyngeal gill slits, endostyle, and post-anal tail at some stage of life.

• Heart: Muscular organ that pumps blood; in chordates, it is typically ventral and not dorsal.

• Pharynx: Region behind the mouth, perforated with gill slits in chordates for filter feeding or respiration.

• Central Nervous System: Consists of a dorsal hollow nerve cord in chordates, unlike the ventral solid nerve cord of many invertebrates.

• Post-anal tail: Tail extending beyond the anus, present in all chordates during some stage of development.

• Notochord: Flexible rod providing skeletal support, present at least during embryonic development.

Lead Question – 2022 (Abroad)
Which one of the following features are not true for chordates?
(a) Heart is dorsal.
(b) Pharynx is perforated by gill slits.
(c) Central nervous system is ventral solid and single.
(d) Post-anal tail is present.
(e) Notochord is present.
Choose the most appropriate answer from the options below:
1. (e) only
2. (a), (d) and (c) only
3. (b) and (c) only
4. (a) and (c) only

Explanation:
Correct answer is option 4. In chordates, the heart is ventral, not dorsal, and the central nervous system is dorsal hollow and single, unlike the ventral solid nerve cord in some invertebrates. Features like pharynx perforated with gill slits, post-anal tail, and notochord are characteristic of chordates. Therefore, statements (a) and (c) are not true for chordates, while (b), (d), and (e) correctly describe chordate features. This distinction highlights chordate evolutionary traits, emphasizing dorsal nerve cord, ventral heart, and presence of notochord and tail as defining anatomical characteristics.

1. In chordates, the notochord is:
1. Absent in all stages
2. Present only in some invertebrates
3. Present at least during embryonic development
4. Replaced entirely by vertebrae in all species
Explanation: Correct answer is Present at least during embryonic development. The notochord is a flexible rod-like structure providing axial support. In vertebrates, it may be partially or completely replaced by vertebrae during development, but all chordates exhibit it in embryonic stages. It is a defining feature that distinguishes chordates from non-chordate animals.

2. The central nervous system of chordates is:
1. Ventral and solid
2. Dorsal and hollow
3. Paired ventral cords
4. Lacking any specialization
Explanation: Correct answer is Dorsal and hollow. Chordates possess a dorsal hollow nerve cord forming the brain and spinal cord. This contrasts with many invertebrates, which have ventral solid nerve cords. The dorsal hollow cord allows efficient signal transmission and centralization of neural processing, facilitating complex sensory and motor functions.

3. The heart in chordates is located:
1. Dorsally
2. Ventral to the alimentary canal
3. Lateral to the body axis
4. Absent
Explanation: Correct answer is Ventral to the alimentary canal. Chordates have a ventral heart that pumps blood towards the dorsal aorta. A dorsal heart is absent. This ventral placement contrasts with the dorsal nerve cord and demonstrates the anatomical organization of chordates, providing efficient circulation aligned with body plan evolution.

4. Post-anal tail is:
1. Absent in all chordates
2. Present only in fish
3. Present at some developmental stage in all chordates
4. Only found in vertebrates
Explanation: Correct answer is Present at some developmental stage in all chordates. The post-anal tail extends beyond the anus and may persist in adults or regress after embryonic development. It aids in locomotion in aquatic species and serves as a structural remnant in terrestrial species, illustrating chordate evolutionary conservation.

5. Which feature is characteristic of the pharynx in chordates?
1. Lacks gill slits
2. Perforated by gill slits
3. Ventral opening only
4. Surrounded by notochord
Explanation: Correct answer is Perforated by gill slits. Chordates have a pharynx with gill slits at some stage of life, allowing filter feeding in protochordates or respiration in fish. This is a key defining feature, along with dorsal nerve cord, notochord, and post-anal tail, distinguishing chordates from non-chordate invertebrates.

6. Which of the following is true for chordates?
1. Heart is dorsal
2. CNS is ventral and solid
3. Post-anal tail is present
4. None of the above
Explanation: Correct answer is Post-anal tail is present. Chordates possess a post-anal tail at least during development. The heart is ventral, not dorsal, and CNS is dorsal hollow and single. The post-anal tail contributes to locomotion or is vestigial, and its presence is a defining chordate characteristic.

7. Assertion-Reason:
Assertion (A): Chordates have a dorsal hollow nerve cord.
Reason (R): The nerve cord lies ventral and solid in all chordates.
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
3. A is true, R is false
4. A is false, R is true
Explanation: Correct answer is option 3. The assertion is true; chordates possess a dorsal hollow nerve cord forming CNS. The reason is false; the ventral solid nerve cord is found in many invertebrates, not chordates. This distinction highlights the evolutionary divergence in nervous system organization between chordates and invertebrates.

8. Matching Type:
Match List-I (Feature) with List-II (Chordate/Non-chordate):
A. Dorsal hollow nerve cord – (i) Chordate
B. Ventral solid nerve cord – (ii) Non-chordate
C. Post-anal tail – (iii) Chordate
D. Heart ventral – (iv) Chordate
1. A–i, B–ii, C–iii, D–iv
2. A–ii, B–i, C–iv, D–iii
3. A–i, B–i, C–ii, D–iv
4. A–iv, B–ii, C–i, D–iii
Explanation: Correct answer is option 1. Dorsal hollow nerve cord, post-anal tail, and ventral heart are chordate features, while ventral solid nerve cord is typical of many non-chordates. Matching clarifies chordate versus non-chordate anatomical characteristics.

9. Fill in the Blanks:
In chordates, the central nervous system is __________ and hollow.
1. Ventral
2. Dorsal
3. Lateral
4. Absent

Chapter: Structural Organisation in Animals; Topic: Circulatory System in Vertebrates; Subtopic: Chambered Heart and Reproductive Nature in Amphibians and Reptiles

Keyword Definitions:

• Amphibians: Vertebrates that can live both on land and in water; examples include frogs and toads.

• Reptiles: Cold-blooded vertebrates with scaly skin, such as snakes, lizards, and crocodiles.

• Oviparous: Animals that lay eggs outside the body where embryos develop.

• Viviparous: Animals that give birth to live young, with embryos developing inside the body.

• Atria: Upper chambers of the heart that receive blood.

• Ventricle: Lower chamber of the heart that pumps blood out.

• Four-chambered heart: Heart with two atria and two ventricles ensuring complete separation of oxygenated and deoxygenated blood.

• Three-chambered heart: Heart with two atria and one ventricle, allowing partial mixing of blood.

• Crocodile: Large aquatic reptile possessing a four-chambered heart unlike other reptiles.

• Statement-based question: A question type where two or more factual statements are compared for correctness.

Lead Question - 2022 (Abroad)

Given below are two statements:

Statement-I: Amphibians and reptiles have a 3-chambered heart with two atria and a single ventricle, and are oviparous in nature.

Statement-II: Crocodiles possess a 4-chambered heart with two ventricles and two atria, and are viviparous in nature.

In the light of the above statements, choose the most appropriate answer from the options given below:

1. Statement-I is correct but Statement-II is incorrect

2. Statement-I is incorrect but Statement-II is correct

3. Both Statement-I and Statement-II are correct

4. Both Statement-I and Statement-II are incorrect

Explanation: Amphibians and most reptiles possess a 3-chambered heart with two atria and a single ventricle, and they are oviparous. Crocodiles are exceptional among reptiles, having a 4-chambered heart, but they are also oviparous, not viviparous. Thus, Statement-I is correct and Statement-II is incorrect. Correct answer: 1

1. SINGLE CORRECT ANSWER MCQ

Which reptile among the following has a four-chambered heart?

1. Lizard

2. Turtle

3. Crocodile

4. Snake

Explanation: Crocodiles have a unique four-chambered heart, unlike most reptiles which possess three chambers. This structure enables complete separation of oxygenated and deoxygenated blood, improving efficiency during diving and swimming. Correct answer: 3

2. SINGLE CORRECT ANSWER MCQ

How many chambers are found in the heart of amphibians?

1. Two

2. Three

3. Four

4. Five

Explanation: Amphibians such as frogs and toads have a three-chambered heart with two atria and one ventricle. The mixing of oxygenated and deoxygenated blood reduces efficiency compared to a four-chambered heart. Correct answer: 2

3. SINGLE CORRECT ANSWER MCQ

Which statement is true about crocodilian reproduction?

1. They are viviparous with parental care

2. They are oviparous with parental care

3. They are viviparous without parental care

4. They are ovoviviparous without parental care

Explanation: Crocodiles are oviparous, meaning they lay eggs. However, they show significant parental care by guarding and assisting hatchlings after hatching, unlike most reptiles. Correct answer: 2

4. SINGLE CORRECT ANSWER MCQ

Which of the following combinations is correct?

1. Amphibians – Four-chambered heart – Viviparous

2. Reptiles – Three-chambered heart – Oviparous

3. Reptiles – Two-chambered heart – Oviparous

4. Amphibians – Two-chambered heart – Oviparous

Explanation: Reptiles generally possess a three-chambered heart and are oviparous. Amphibians also have three-chambered hearts, not two. Correct answer: 2

5. SINGLE CORRECT ANSWER MCQ

In crocodiles, separation of oxygenated and deoxygenated blood occurs because of:

1. Presence of two atria only

2. Presence of complete interventricular septum

3. Absence of septum

4. Single ventricle

Explanation: Crocodiles have a complete interventricular septum dividing the ventricle into two chambers, enabling complete separation of oxygenated and deoxygenated blood like birds and mammals. Correct answer: 2

6. SINGLE CORRECT ANSWER MCQ

Amphibians have mixed blood circulation because:

1. They lack lungs

2. They have a single ventricle

3. They have four chambers

4. They have two ventricles

Explanation: Amphibians have two atria and a single ventricle, where oxygenated and deoxygenated blood mix, leading to partial or mixed circulation. Correct answer: 2

7. ASSERTION-REASON MCQ

Assertion (A): Crocodiles have a four-chambered heart like mammals.

Reason (R): The complete separation of blood improves efficiency of oxygen transport.

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: Crocodiles possess a complete four-chambered heart, ensuring separation of oxygenated and deoxygenated blood, leading to high efficiency in oxygen delivery. Correct answer: 1

8. MATCHING TYPE MCQ

Match the animal with its heart type:

Column A:

1. Frog

2. Crocodile

3. Fish

4. Bird

Column B:

1. Two-chambered heart

2. Three-chambered heart

3. Four-chambered heart

Explanation: Fish have a two-chambered heart, frogs have three, and crocodiles and birds have four chambers. Correct matching: 1-2, 2-3, 3-1, 4-3

9. FILL IN THE BLANKS / COMPLETION MCQ

Crocodiles have a _______ heart and are _______ in nature.

1. Three-chambered, oviparous

2. Four-chambered, oviparous

3. Four-chambered, viviparous

4. Three-chambered, viviparous

Explanation: Crocodiles possess a four-chambered heart and are oviparous, laying eggs with extensive parental care. Correct answer: 2

10. CHOOSE THE CORRECT STATEMENTS MCQ

Statement I: Amphibians and reptiles have a three-chambered heart.
Statement II: Crocodiles have a four-chambered heart but are oviparous.

1. Only Statement I is correct

2. Only Statement II is correct

3. Both Statements I and II are correct

4. Both Statements I and II are incorrect

Explanation: Amphibians and most reptiles have a three-chambered heart, while crocodiles are an exception with four chambers. Both are oviparous. Hence, both statements are correct. Correct answer: 3

Topic: Fish Anatomy; Subtopic: Respiratory Adaptations

Keyword Definitions:

• Air bladder: A gas-filled sac present in certain fish that helps in buoyancy control and maintaining depth in water.

• Osteichthyes: Bony fishes that have a skeleton primarily made of bone, often possessing a swim bladder.

• Aves: Class of birds; warm-blooded, feathered animals with lungs, no air bladder as in fish.

• Cyclostomata: Jawless fishes like lampreys and hagfish, which lack paired fins and an air bladder.

• Chondrichthyes: Cartilaginous fishes like sharks and rays; they do not have a true air bladder, using liver oils for buoyancy.

• Buoyancy: Ability of an organism to float or maintain position in a fluid medium.

• Respiratory Adaptation: Structural modification in organs for efficient breathing in specific environments.

• Gas regulation: Control of gas content in the body or organ like the air bladder to maintain equilibrium.

• Swim bladder: Synonymous with air bladder in bony fishes, important for buoyancy control.

• Hydrostatic organ: Organ like air bladder that helps fish maintain vertical position without energy expenditure.

• Fish Anatomy: Study of structure and organs of fish, including skeletal, respiratory, and buoyancy adaptations.

Lead Question - 2022 (Abroad)

Air bladder is found in:

1. Osteichthyes

2. Aves

3. Cyclostomata

4. Chondrichthyes

Explanation: The air bladder, also known as the swim bladder, is present in Osteichthyes or bony fishes. It functions as a hydrostatic organ that helps in maintaining buoyancy and stabilizing depth without active swimming. Cartilaginous fishes like sharks use liver oils for buoyancy, while jawless fishes and birds lack such a structure. This adaptation allows fish to conserve energy while maintaining vertical position in water. It also assists in gas regulation, sound production, and respiratory adjustments in some species. Answer: 1

1. SINGLE CORRECT ANSWER MCQ

Which function is primarily served by the air bladder in bony fishes?

1. Respiration only

2. Buoyancy control

3. Reproduction

4. Locomotion

Explanation: The air bladder in bony fishes mainly functions in buoyancy control. It allows the fish to maintain its vertical position in water without expending energy. Though it may aid in respiration in primitive forms, its main role is hydrostatic regulation. Other functions like reproduction and locomotion are not primary roles of this organ. By regulating gas, it stabilizes depth and helps conserve energy during swimming. Answer: 2

2. SINGLE CORRECT ANSWER MCQ

In which of the following fish is the air bladder absent?

1. Osteichthyes

2. Chondrichthyes

3. Teleosts

4. Perch

Explanation: Chondrichthyes, which include sharks and rays, lack a true air bladder. Instead, they rely on large, oil-rich livers to maintain buoyancy. Osteichthyes and teleosts have a swim bladder. The absence of this organ in Chondrichthyes is an adaptation to their cartilaginous structure and active predatory lifestyle, demonstrating diverse evolutionary strategies in fish anatomy for maintaining hydrostatic equilibrium. Answer: 2

3. SINGLE CORRECT ANSWER MCQ

The air bladder is primarily located in which body cavity?

1. Abdominal cavity

2. Thoracic cavity

3. Pelvic cavity

4. None of the above

Explanation: The air bladder is located dorsally in the abdominal cavity of bony fishes. It lies above the digestive tract and assists in maintaining buoyancy. Its dorsal positioning is optimal for stabilizing the fish’s center of gravity and hydrostatic equilibrium. This placement also allows pressure regulation with minor adjustments in gas content. It is absent in Chondrichthyes and jawless fishes. Understanding anatomical location is crucial for studying physiological adaptations in aquatic vertebrates. Answer: 1

4. SINGLE CORRECT ANSWER MCQ

Which evolutionary advantage does the air bladder provide?

1. Rapid locomotion

2. Energy-efficient buoyancy

3. Enhanced vision

4. Stronger jaws

Explanation: The air bladder offers energy-efficient buoyancy, allowing fish to maintain depth without continuous swimming. This adaptation conserves energy and supports survival in various aquatic niches. It may also aid in sound production or minor respiratory adjustments. It is not directly responsible for locomotion speed, vision, or jaw strength. Evolutionary development of the swim bladder represents a critical adaptation in bony fishes for effective utilization of aquatic habitats. Answer: 2

5. SINGLE CORRECT ANSWER MCQ

Which gas is primarily present in the swim bladder for buoyancy control?

1. Oxygen

2. Nitrogen

3. Carbon dioxide

4. Hydrogen

Explanation: The air bladder contains primarily oxygen, which can be secreted or absorbed to regulate buoyancy in bony fishes. Nitrogen and carbon dioxide are minor constituents. Hydrogen is not involved. Gas regulation allows precise control of hydrostatic pressure, letting fish maintain position without energy expenditure. This physiological adaptation is essential for depth adjustment and environmental survival. Understanding this aids in comparative anatomy and evolutionary studies of aquatic vertebrates. Answer: 1

6. SINGLE CORRECT ANSWER MCQ

Which of the following fish groups has a pneumatic duct connecting swim bladder to esophagus?

1. Physostomous fishes

2. Physoclistous fishes

3. Chondrichthyes

4. Cyclostomata

Explanation: Physostomous fishes possess a pneumatic duct connecting the swim bladder to the esophagus, allowing gulping or releasing air to adjust buoyancy. Physoclistous fishes lack this duct and rely on gas diffusion from blood. Cartilaginous and jawless fishes do not possess a swim bladder. This structural distinction is crucial in fish anatomy for understanding gas regulation mechanisms and buoyancy adaptations across evolutionary lineages. Answer: 1

7. ASSERTION-REASON MCQ

Assertion (A): Air bladder is absent in sharks.

Reason (R): Sharks rely on large, oil-rich livers for buoyancy instead of air bladders.

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: Sharks and other Chondrichthyes do not possess an air bladder; instead, their large, oil-rich livers provide buoyancy. This adaptation allows them to maintain depth efficiently in the absence of a hydrostatic organ. Both Assertion and Reason are true, and the Reason correctly explains why air bladder is absent. This reflects evolutionary divergence in buoyancy mechanisms between bony and cartilaginous fishes. Answer: 1

8. MATCHING TYPE MCQ

Match the fish group with its buoyancy adaptation:

Column A:

1. Osteichthyes

2. Chondrichthyes

3. Cyclostomata

4. Teleosts

Column B:

1. Oil-rich liver

2. Air bladder

3. No specialized buoyancy organ

4. Air bladder with pneumatic duct

Explanation: Correct matching: Osteichthyes → Air bladder, Chondrichthyes → Oil-rich liver, Cyclostomata → No specialized buoyancy organ, Teleosts → Air bladder with pneumatic duct. These adaptations reflect diverse evolutionary strategies for maintaining buoyancy in aquatic habitats. Understanding these mechanisms is essential for comparative anatomy and functional physiology of fishes. Answer: Osteichthyes-2, Chondrichthyes-1, Cyclostomata-3, Teleosts-4

9. FILL IN THE BLANKS / COMPLETION MCQ

The organ that helps fish regulate buoyancy and maintain vertical position is called _______.

1. Air bladder

2. Liver

3. Swim fin

4. Gill chamber

Explanation: The air bladder, or swim bladder, helps bony fishes regulate buoyancy and maintain vertical position in water. It acts as a hydrostatic organ with controlled gas secretion and absorption. This reduces energy expenditure during swimming. Cartilaginous and jawless fishes use other adaptations, like oil-rich liver or active swimming, for maintaining depth. Understanding this organ’s function is critical for studying fish physiology and evolutionary adaptations to aquatic life. Answer: 1

10. CHOOSE THE CORRECT STATEMENTS MCQ

Statement I: Swim bladder aids in buoyancy regulation.
Statement II: Chondrichthyes possess a true air bladder.

1. Only Statement I is correct

2. Only Statement II is correct

3. Both Statements I and II are correct

4. Both Statements I and II are incorrect

Explanation: Swim bladder is present in bony fishes and aids in buoyancy regulation, making Statement I correct. Chondrichthyes, including sharks and rays, lack a true air bladder, relying on oil-rich livers instead. Therefore, Statement II is incorrect. This distinction highlights evolutionary divergence in buoyancy adaptations among aquatic vertebrates. Understanding the presence or absence of air bladder aids in functional anatomy studies and ecological adaptations of fishes. Answer: 1

Topic: Digestive System in Animals
Subtopic: Specialization of Digestive Tract

Keyword Definitions:
• Digestive tract: Continuous tube from mouth to anus where food is ingested, digested, and absorbed.
• Crop: Expanded portion of alimentary canal for temporary storage of food.
• Gizzard: Muscular chamber that grinds food mechanically, often with ingested grit.
• Bufo: Genus of frogs.
• Catla: Freshwater fish species.
• Columba: Genus of pigeons.
• Pavo: Genus of peafowl.
• Psittacula: Genus of parakeets.
• Corvus: Genus of crows.
• Crocodilus: Genus of crocodiles.

Lead Question (2022):
In which of the following animals, digestive tract has additional chambers like crop and gizzard ?
(1) Bufo, Calaenoptera, Bangarus
(2) Catla, Columba, Crocodilus
(3) Pavo, Psittacula, Corvus
(4) Corous, Columba, Chameleon

Explanation: The correct answer is (3). Birds such as Pavo (peafowl), Psittacula (parakeets), and Corvus (crows) possess a crop for temporary food storage and a gizzard for grinding food, adaptations to aid mechanical digestion. Amphibians, reptiles, and most fishes lack both specialized chambers.

Guessed MCQs:

1. Single Correct Answer:
Which organ in birds stores food temporarily before digestion?
(a) Stomach
(b) Crop
(c) Gizzard
(d) Small intestine
Explanation: The correct answer is (b). In birds, the crop is an expanded portion of the esophagus used to store food temporarily before it enters the gizzard for grinding.

2. Single Correct Answer:
Which part of bird digestive system grinds food mechanically?
(a) Crop
(b) Gizzard
(c) Pancreas
(d) Liver
Explanation: The correct answer is (b). The gizzard is a muscular part of the bird’s stomach containing grit that grinds food mechanically, facilitating digestion without teeth.

3. Single Correct Answer:
In which of the following animals is a gizzard absent?
(a) Pavo
(b) Psittacula
(c) Corvus
(d) Bufo
Explanation: The correct answer is (d). Bufo (frogs) lack a gizzard. Gizzard is characteristic of birds for grinding food, whereas amphibians and most reptiles rely on enzymatic digestion.

4. Assertion-Reason MCQ:
Assertion (A): Birds have both crop and gizzard in their digestive system.
Reason (R): Crop stores food temporarily and gizzard grinds it.
(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). Birds possess both crop and gizzard; the crop stores food temporarily while the gizzard mechanically grinds it, making R the correct explanation of A.

5. Single Correct Answer:
Which of the following adaptations aids birds in eating hard seeds?
(a) Crop
(b) Gizzard
(c) Cloaca
(d) Small intestine
Explanation: The correct answer is (b). The gizzard contains muscular walls and grit to grind hard seeds, allowing efficient digestion of tough foods without teeth.

6. Single Correct Answer:
Which organ is absent in fishes like Catla for mechanical food digestion?
(a) Stomach
(b) Gizzard
(c) Intestine
(d) Liver
Explanation: The correct answer is (b). Catla and most fishes lack a gizzard; mechanical digestion is minimal, and food is digested primarily through enzymatic action in the stomach and intestine.

7. Matching Type:
Match the following:
Column A
1. Crop
2. Gizzard
3. Small intestine
4. Liver
Column B
A. Food grinding
B. Enzymatic digestion
C. Food storage
D. Bile production
Options:
(a) 1-C, 2-A, 3-B, 4-D
(b) 1-A, 2-C, 3-B, 4-D
(c) 1-C, 2-B, 3-A, 4-D
(d) 1-B, 2-A, 3-C, 4-D
Explanation: The correct answer is (a). Crop stores food (1-C), gizzard grinds food (2-A), small intestine digests food enzymatically (3-B), and liver produces bile for digestion (4-D).

8. Fill in the Blanks:
In birds, _______ stores food temporarily, while _______ mechanically grinds it for digestion.
(a) Crop, Gizzard
(b) Gizzard, Crop
(c) Small intestine, Crop
(d) Crop, Small intestine
Explanation: The correct answer is (a). The crop temporarily stores food, and the gizzard, a muscular stomach part with grit, mechanically grinds the food for digestion.

9. Single Correct Answer:
Which of the following birds uses crop and gizzard for feeding adaptation?
(a) Peafowl
(b) Shark
(c) Catla
(d) Frog
Explanation: The correct answer is (a). Peafowl (Pavo) have both crop and gizzard, adaptations to store and grind food efficiently. Sharks, Catla, and frogs lack these chambers.

10. Choose the correct statements:
(a) Crop is present in birds for food storage
(b) Gizzard is present in birds for mechanical digestion
(c) Both crop and gizzard are present in reptiles
(d) Only enzymatic digestion occurs in amphibians
Explanation: The correct answer is (a), (b), and (d). Birds have crop and gizzard; reptiles generally lack a crop and gizzard, and amphibians digest food enzymatically without specialized chambers.

Topic: Classification of Chordates
Subtopic: Vertebrates vs Invertebrate Chordates

Keyword Definitions:
• Chordates: Animals possessing a notochord, dorsal nerve cord, pharyngeal slits, and post-anal tail at some stage.
• Vertebrates: Chordates in which the notochord is replaced by a vertebral column in adults.
• Notochord: Flexible rod providing axial support in embryonic stage of chordates.
• Vertebral column: Bony or cartilaginous structure replacing notochord in vertebrates.
• Invertebrate chordates: Chordates without vertebral column, e.g., amphioxus, tunicates.
• Dorsal nerve cord: Hollow cord present in chordates, above the notochord.
• Pharyngeal slits: Openings in pharyngeal region for filter feeding or respiration.
• Post-anal tail: Tail extending beyond anus in chordates.
• Embryonic stage: Developmental stage showing chordate features even if absent in adult.
• Classification: Systematic grouping of organisms based on shared characteristics.

Lead Question (2022):
Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): All vertebrates are chordates but all chordates are not vertebrates.
Reason (R): Notochord is replaced by vertebral column in the adult vertebrates.
In the light of the above statements, choose the most appropriate answer from the options given below:
(1) Both (A) and (R) are correct but (R) is not the correct explanation of (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 (1). All vertebrates belong to chordates, but invertebrate chordates like amphioxus exist, so not all chordates are vertebrates. While the notochord is replaced by vertebral column in vertebrates (R), this fact explains the vertebrate structure, not the distinction between chordates and vertebrates.

Guessed MCQs:

1. Single Correct Answer:
Which of the following is an invertebrate chordate?
(a) Amphioxus
(b) Frog
(c) Pigeon
(d) Shark
Explanation: The correct answer is (a). Amphioxus is an invertebrate chordate possessing a notochord but lacks a vertebral column, unlike vertebrates such as frogs, pigeons, and sharks.

2. Single Correct Answer:
In vertebrates, the notochord is present during:
(a) Adult stage
(b) Embryonic stage
(c) Both adult and embryonic stages
(d) Never
Explanation: The correct answer is (b). In vertebrates, the notochord is present transiently during embryonic development and is later replaced by the vertebral column.

3. Single Correct Answer:
Which structure is common to all chordates at some stage?
(a) Vertebral column
(b) Notochord
(c) Wings
(d) Limbs
Explanation: The correct answer is (b). All chordates exhibit a notochord at some developmental stage, whereas vertebral column is restricted to vertebrates.

4. Assertion-Reason MCQ:
Assertion (A): All chordates possess a dorsal nerve cord.
Reason (R): Dorsal nerve cord lies above the notochord.
(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). All chordates have a dorsal hollow nerve cord, which lies above the notochord, providing structural support and neural function.

5. Single Correct Answer:
Which chordate feature aids in filter feeding in primitive species?
(a) Notochord
(b) Pharyngeal slits
(c) Post-anal tail
(d) Vertebral column
Explanation: The correct answer is (b). Pharyngeal slits in primitive chordates like tunicates and amphioxus facilitate filter feeding, while other structures serve support or locomotion.

6. Single Correct Answer:
In vertebrates, the post-anal tail is present:
(a) Only in embryos
(b) Throughout life in some species
(c) Absent in all adults
(d) Only in invertebrate chordates
Explanation: The correct answer is (b). In vertebrates, post-anal tail is present in embryos and retained in adults of certain species like fishes, aiding locomotion.

7. Matching Type:
Match the following:
Column A
1. Notochord
2. Vertebral column
3. Amphioxus
4. Shark
Column B
A. Vertebrate
B. Invertebrate chordate
C. Embryonic support
D. Adult support
Options:
(a) 1-C, 2-D, 3-B, 4-A
(b) 1-D, 2-C, 3-B, 4-A
(c) 1-C, 2-D, 3-A, 4-B
(d) 1-B, 2-A, 3-C, 4-D
Explanation: The correct answer is (a). Notochord provides embryonic support (1-C), vertebral column provides adult support (2-D), amphioxus is an invertebrate chordate (3-B), and shark is a vertebrate (4-A).

8. Fill in the Blanks:
In vertebrates, the notochord is replaced by _______ in the adult stage, while in invertebrate chordates it _______.
(a) Vertebral column, persists
(b) Nerve cord, disappears
(c) Pharyngeal slits, disappears
(d) Vertebral column, disappears
Explanation: The correct answer is (a). In vertebrates, the notochord is replaced by the vertebral column in adults, whereas it persists in invertebrate chordates.

9. Single Correct Answer:
Which of the following is NOT a feature of chordates?
(a) Notochord
(b) Dorsal hollow nerve cord
(c) Jointed limbs
(d) Post-anal tail
Explanation: The correct answer is (c). Jointed limbs are characteristic of vertebrates, not a general feature of chordates; chordates share notochord, dorsal hollow nerve cord, pharyngeal slits, and post-anal tail.

10. Choose the correct statements:
(a) All vertebrates are chordates
(b) All chordates are vertebrates
(c) Notochord is replaced by vertebral

Topic: Nitrogenous Waste Elimination
Subtopic: Types of Excretion

Keyword Definitions:
• Nitrogenous Waste: Metabolic waste containing nitrogen produced from protein and nucleic acid metabolism.
• Excretion: Process of eliminating metabolic wastes from the body.
• Uricotelic: Organisms excreting nitrogen mainly as uric acid.
• Ureotelic: Organisms excreting nitrogen mainly as urea.
• Ammonotelic: Organisms excreting nitrogen mainly as ammonia.
• Pellet or Paste: Solid or semi-solid excretory product, typical of uric acid excretion.
• Salamandra: Genus of amphibians; some species excrete uric acid as paste.
• Hippocampus: Genus of seahorses.
• Pavo: Genus of peafowl.
• Ornithorhynchus: Genus of platypus.

Lead Question (2022):
Nitrogenous waste is excreted in the form of pellet or paste by:
(1) Salamandra
(2) Hippocampus
(3) Pavo
(4) Ornithorhynchus

Explanation: The correct answer is (3). Pavo, the peafowl, being a bird, is uricotelic and excretes nitrogenous waste as semi-solid uric acid in the form of pellets or paste. This adaptation reduces water loss and conserves water, which is essential for terrestrial birds living in varied habitats.

Guessed MCQs:

1. Single Correct Answer:
Which type of nitrogenous waste is excreted by birds?
(a) Uric acid
(b) Urea
(c) Ammonia
(d) Creatinine
Explanation: The correct answer is (a). Birds are uricotelic, excreting nitrogenous waste mainly as uric acid in a semi-solid form, which minimizes water loss and allows survival in terrestrial habitats with limited water availability.

2. Single Correct Answer:
Which organism is ureotelic, excreting nitrogen primarily as urea?
(a) Frog
(b) Pavo
(c) Salamandra
(d) Hippocampus
Explanation: The correct answer is (c). Salamandra, an amphibian, excretes nitrogenous waste mainly as urea dissolved in water, classifying it as ureotelic. Ureotelic excretion is common in terrestrial amphibians to conserve nitrogen and regulate osmotic balance.

3. Assertion-Reason MCQ:
Assertion (A): Birds excrete nitrogenous waste as pellets.
Reason (R): Uric acid is insoluble in water and conserves water in terrestrial environments.
(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 false
(d) A is false, R is true
Explanation: The correct answer is (a). Birds like Pavo excrete nitrogen as uric acid pellets. Insolubility of uric acid ensures minimal water loss, an adaptation for terrestrial life, making the reason correctly explain the assertion.

4. Matching Type MCQ:
Match the organism with its nitrogenous excretion type:
A. Pavo – (i) Uricotelic
B. Salamandra – (ii) Ureotelic
C. Hippocampus – (iii) Ammonotelic
D. Ornithorhynchus – (iv) Ureotelic
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–i, B–iii, C–ii, D–iv
Explanation: The correct answer is (1). Pavo excretes uric acid (uricotelic), Salamandra excretes urea (ureotelic), Hippocampus excretes ammonia (ammonotelic), and Ornithorhynchus excretes urea (ureotelic), reflecting adaptations to water availability and habitat.

5. Single Correct Answer:
Which nitrogenous waste form minimizes water loss?
(a) Uric acid
(b) Urea
(c) Ammonia
(d) Creatinine
Explanation: The correct answer is (a). Uric acid is insoluble and excreted as a semi-solid paste or pellet, which reduces water loss. Birds and many reptiles use this form to survive in terrestrial habitats with limited water availability.

6. Single Correct Answer:
Which organism is ammonotelic?
(a) Hippocampus
(b) Pavo
(c) Salamandra
(d) Ornithorhynchus
Explanation: The correct answer is (a). Hippocampus, a marine fish, excretes nitrogen primarily as ammonia directly into surrounding water. Ammonotelic excretion is common in aquatic animals where water is abundant for dilution.

7. Fill in the Blanks:
Excretion of nitrogenous waste as ________ helps birds conserve water.
(a) pellets
(b) urea
(c) ammonia
(d) sweat
Explanation: The correct answer is (a). Birds excrete nitrogenous waste as pellets of uric acid, a semi-solid form, which reduces water loss and is an adaptation for terrestrial environments with limited water.

8. Single Correct Answer:
Which nitrogenous waste is soluble in water and excreted by amphibians?
(a) Urea
(b) Uric acid
(c) Ammonia
(d) Creatinine
Explanation: The correct answer is (a). Amphibians like Salamandra are ureotelic and excrete urea, a water-soluble nitrogenous waste, which facilitates excretion in moist environments while maintaining nitrogen balance.

9. Single Correct Answer:
Which adaptation allows birds to live in dry terrestrial habitats?
(a) Excretion of uric acid as paste
(b) Excretion of urea
(c) Excretion of ammonia
(d) Storing nitrogen in liver
Explanation: The correct answer is (a). Birds excrete nitrogen as insoluble uric acid pellets, which reduces water loss significantly. This adaptation supports survival in terrestrial and arid habitats.

10. Choose the correct statements:
(a) Birds are uricotelic.
(b) Amphibians like Salamandra are ureotelic.
(c) Marine fish excrete ammonia (ammonotelic).
(d) Pavo excretes urea in liquid form.
Options:
1. a, b, c only
2. a and d only
3. b and d only
4. All statements
Explanation: The correct answer is (1). Birds excrete uric acid (uricotelic), Salamandra excretes urea (ureotelic), and marine fish excrete ammonia (ammonotelic). Statement (d) is incorrect because Pavo excretes nitrogenous waste as uric acid pellets, not urea.

Subtopic: Arthropod Exoskeleton

Keyword Definitions:

• Exoskeleton: External skeleton that supports and protects the body of an animal.

• Arthropods: Invertebrate animals with segmented bodies, jointed appendages, and a chitinous exoskeleton.

• Chitin: A long-chain polymer of N-acetylglucosamine forming the exoskeleton of arthropods.

• Cellulose: Carbohydrate polymer forming the cell wall of plants.

• Glucosamine: Amino sugar derived from glucose, not forming exoskeleton directly.

• Cutin: Waxy polymer forming protective layer in plants.

• Exoskeleton Functions: Protection, support, prevention of water loss, and muscle attachment.

• Segmentation: Division of body into repeating units, characteristic of arthropods.

• Molting: Process of shedding exoskeleton for growth in arthropods.

• Jointed Appendages: Limbs with flexible joints used for movement and manipulation.

Lead Question (2022)
Exoskeleton of arthropods is composed of:
(1) Cellulose
(2) Chitin
(3) Glucosamine
(4) Cutin

Explanation:
Arthropod exoskeleton is primarily composed of chitin, a nitrogenous polysaccharide that provides rigidity and protection. Cellulose is found in plants, glucosamine is a building block but not the main component, and cutin is a plant wax. Correct answer is (2).

1. Single Correct Answer MCQ:
Which process allows arthropods to grow by shedding their exoskeleton?
(1) Photosynthesis
(2) Molting
(3) Metamorphosis
(4) Regeneration

Explanation:
Arthropods grow by molting, where the old exoskeleton is shed, and a new larger one forms. Photosynthesis occurs in plants, metamorphosis involves transformation between life stages, and regeneration is replacement of lost body parts. Correct answer is (2).

2. Single Correct Answer MCQ:
The primary function of an arthropod exoskeleton is:
(1) Energy storage
(2) Muscle attachment and protection
(3) Photosynthesis
(4) Respiration

Explanation:
The exoskeleton provides protection against predators and physical damage, prevents water loss, and serves as a surface for muscle attachment. It does not function in energy storage, photosynthesis, or respiration. Correct answer is (2).

3. Single Correct Answer MCQ:
Which component makes arthropod exoskeleton rigid?
(1) Protein only
(2) Chitin
(3) Lignin
(4) Lipids

Explanation:
Chitin, sometimes combined with proteins and minerals, forms a strong and rigid exoskeleton in arthropods, allowing support and protection. Lignin is found in plants, and lipids provide waxy coatings. Correct answer is (2).

4. Single Correct Answer MCQ:
Which of the following is NOT a function of arthropod exoskeleton?
(1) Support
(2) Protection
(3) Gas exchange
(4) Muscle attachment

Explanation:
Arthropod exoskeleton provides support, protection, prevents water loss, and serves as a muscle attachment site. Gas exchange occurs via gills or trachea, not the exoskeleton. Correct answer is (3).

5. Single Correct Answer MCQ:
In which group is exoskeleton absent?
(1) Insects
(2) Crustaceans
(3) Annelids
(4) Arachnids

Explanation:
Annelids (segmented worms) do not have an exoskeleton; their body is soft and covered by a cuticle. Insects, crustaceans, and arachnids all possess chitinous exoskeletons. Correct answer is (3).

6. Single Correct Answer MCQ:
Which mineral may be added to arthropod exoskeleton for extra hardness?
(1) Calcium carbonate
(2) Iron
(3) Sodium chloride
(4) Potassium

Explanation:
Some crustaceans add calcium carbonate to their chitinous exoskeleton for hardness and rigidity. Iron, sodium chloride, and potassium are not major components for exoskeleton strength. Correct answer is (1).

7. Assertion-Reason MCQ:
Assertion (A): Chitin provides flexibility to arthropod exoskeleton.
Reason (R): Chitin is a polysaccharide forming the main component of the exoskeleton.
Options:
(1) Both A and R correct, R explains A
(2) A correct, R incorrect
(3) A incorrect, R correct
(4) Both A and R incorrect

Explanation:
Chitin forms the primary structure of the exoskeleton, giving rigidity rather than flexibility. Therefore, assertion is incorrect, but reason is correct. Correct answer is (3).

8. Matching Type MCQ:
Match arthropods with exoskeleton type:
A. Insect — 1. Chitin
B. Crab — 2. Chitin + Calcium
C. Spider — 3. Chitin
D. Worm — 4. None
Options:
(1) A–1, B–2, C–3, D–4
(2) A–2, B–1, C–3, D–4
(3) A–1, B–3, C–2, D–4
(4) A–1, B–2, C–4, D–3

Explanation:
Insects and spiders have chitinous exoskeletons (A–1, C–3). Crabs have chitin with calcium for hardness (B–2). Worms lack exoskeleton (D–4). Correct answer is (1).

9. Fill in the Blanks MCQ:
Arthropods grow by shedding their ________ during molting.
(1) Endoskeleton
(2) Exoskeleton
(3) Cell wall
(4) Cuticle only

Explanation:
During molting, arthropods shed their exoskeleton to allow growth. Endoskeletons occur in vertebrates, and cell wall or cuticle alone are not involved in arthropod molting. Correct answer is (2).

10. Choose the correct statements MCQ:
(a) Exoskeleton is made of chitin
(b) Molting allows growth
(c) Exoskeleton participates in gas exchange
(d) Calcium may reinforce exoskeleton
Options:
(1) a, b, d only
(2) a, c only
(3) b, c, d only
(4) a, b, c, d

Explanation:
Exoskeleton is chitinous (a), molting allows growth (b), and calcium may reinforce it (d). Gas exchange occurs via gills or trachea, not exoskeleton (c). Correct answer is (1).

Topic: Non-Chordates

Subtopic: General Characteristics

Keyword Definitions:

• Metagenesis Alternation of generations between sexual and asexual phases in some organisms.

• Echinoderms Marine triploblastic, coelomate animals with a water vascular system and radial symmetry in adults.

• Roundworms Nematodes with organ-system level organization, pseudocoelomate body plan, and bilateral symmetry.

• Ctenophores Marine animals with comb plates used for locomotion, not digestion.

• Water vascular system A unique hydraulic system in echinoderms used for locomotion, respiration, and food capture.

Lead Question - 2021

Read the following statements
(a) Metagenesis is observed in Helminths
(b) Echinoderms are triploblastic and coelomate animals.
(c) Round worms have organ-system level of body organization
(d) Combplates present in ctenophores help in digestion.
(e) Water vascular system is characteristic of Echinoderms
Choose the correct answer from the options given below.
(1) (a), (b) and (c) are correct
(2) (a), (d) and (e) are correct
(3) (b), (c) and (e) are correct
(4) (c), (d) and (e) are correct

Explanation: Metagenesis is found in coelenterates, not helminths. Comb plates of ctenophores aid in locomotion, not digestion. Echinoderms are triploblastic and coelomate. Roundworms show organ-system organization. The water vascular system is unique to echinoderms. Thus, correct statements are (b), (c), and (e). Answer is option (3).

1. Which one is a characteristic feature of echinoderms?
(1) Flame cells
(2) Nephridia
(3) Water vascular system
(4) Malpighian tubules

Explanation: Echinoderms lack excretory organs like flame cells or nephridia. Instead, their locomotion, food capture, and respiration depend on the water vascular system. This feature is unique among animals. Thus, the correct answer is water vascular system.

2. The organ-system level of organization first appeared in:
(1) Porifera
(2) Coelenterata
(3) Platyhelminthes
(4) Nematoda

Explanation: The first phylum to show organ-system level organization is Platyhelminthes. They are triploblastic acoelomates with distinct organ systems like excretory flame cells. Thus, the correct answer is Platyhelminthes.

3. Comb plates in ctenophores are primarily used for:
(1) Locomotion
(2) Respiration
(3) Digestion
(4) Reproduction

Explanation: Comb plates are rows of fused cilia in ctenophores that beat in a coordinated manner to help in locomotion. They are not involved in digestion, respiration, or reproduction. Thus, the correct answer is locomotion.

4. Assertion (A): Roundworms are pseudocoelomates.
Reason (R): Their body cavity is not lined by mesoderm.
(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, R is false
(4) A is false, R is true

Explanation: Roundworms are pseudocoelomates because their body cavity is derived from blastocoel and not fully lined by mesodermal epithelium. Hence, both Assertion and Reason are true, and Reason explains Assertion. Correct option is (1).

5. Match the following:
A. Platyhelminthes - i. Flame cells
B. Annelida - ii. Nephridia
C. Arthropoda - iii. Malpighian tubules
D. Echinodermata - iv. Water vascular system
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: Excretory structures vary: flame cells in platyhelminths, nephridia in annelids, Malpighian tubules in arthropods, and water vascular system in echinoderms. Thus, the correct answer is option (1).

6. The diploblastic condition is found in:
(1) Porifera
(2) Coelenterata
(3) Platyhelminthes
(4) Nematoda

Explanation: Diploblastic animals develop from two germ layers, ectoderm and endoderm, with mesoglea in between. Coelenterates show this condition. Porifera are cellular, while platyhelminthes and nematodes are triploblastic. Thus, the correct answer is coelenterata.

7. Fill in the blank:
__________ are called "living fossils" among invertebrates.
(1) Limulus
(2) Periplaneta
(3) Pinctada
(4) Octopus

Explanation: Limulus, the king crab, is known as a living fossil because it has persisted almost unchanged for millions of years. Thus, the correct answer is Limulus.

8. Choose the correct statements about echinoderms:
(1) Adults show radial symmetry
(2) They are exclusively marine
(3) They possess a water vascular system
(4) All of these

Explanation: Echinoderms are exclusively marine, triploblastic, coelomate animals with radial symmetry in adults and a water vascular system. All statements are true. Therefore, the correct answer is all of these.

9. Which one of the following animals shows metagenesis?
(1) Obelia
(2) Taenia
(3) Ascaris
(4) Limulus

Explanation: Metagenesis is alternation between asexual polyp and sexual medusa forms in coelenterates like Obelia. It is not seen in helminths like Taenia or nematodes like Ascaris. Thus, the correct answer is Obelia.

10. In ctenophores, digestion is:
(1) Extracellular only
(2) Intracellular only
(3) Both extracellular and intracellular
(4) Absent

Explanation: Ctenophores exhibit both extracellular digestion in the gastrovascular cavity and intracellular digestion within cells. Hence, the correct answer is both extracellular and intracellular.

Subtopic: Representative Organisms

• Physalia: Marine colonial cnidarian known as Portuguese Man of War.

• Limulus: Horseshoe crab, considered a living fossil.

• Ancylostoma: Parasitic nematode, commonly known as hookworm.

• Pinctada: Pearl-producing oyster.

• Living fossil: Species that has remained morphologically similar over long geological periods.

• Hookworm: Blood-feeding intestinal parasite of humans.

• Pearl oyster: Marine bivalve producing natural pearls.

• Portuguese Man of War: Colonial hydrozoan with floating gas-filled structure.

• Phylum: Major taxonomic group containing related classes of organisms.

• Classification: Systematic arrangement of organisms based on similarities and evolutionary relationships.

• Representative organism: Typical species used to describe a phylum or class.

Lead Question - 2021

Match the following
List - I    List - II
(a) Physalia    (i) Pearl oyster
(b) Limulus    (ii) Portuguese Man of War
(c) Ancylostoma    (iii) Living fossil
(d) Pinctada    (iv) Hookworm

Options:
(1) (a)-(iv), (b)-(i), (c)-(iii), (d)-(ii)
(2) (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i)
(3) (a)-(i), (b)-(iv), (c)-(iii), (d)-(ii)
(4) (a)-(ii), (b)-(iii), (c)-(i), (d)-(iv)

Explanation: Physalia is the Portuguese Man of War, Limulus is a living fossil, Ancylostoma is a hookworm, and Pinctada is a pearl oyster. The correct matching is (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i). Answer: Option 2.

1. Single Correct Answer MCQ: Physalia belongs to which group?
Options:
A. Pearl oyster
B. Portuguese Man of War
C. Living fossil
D. Hookworm

Explanation: Physalia is a marine cnidarian known as the Portuguese Man of War. Answer: Portuguese Man of War.

2. Single Correct Answer MCQ: Limulus is commonly called:
Options:
A. Living fossil
B. Pearl oyster
C. Hookworm
D. Portuguese Man of War

Explanation: Limulus, the horseshoe crab, has remained morphologically similar over millions of years, making it a living fossil. Answer: Living fossil.

3. Single Correct Answer MCQ: Ancylostoma is a type of:
Options:
A. Hookworm
B. Pearl oyster
C. Portuguese Man of War
D. Living fossil

Explanation: Ancylostoma is a parasitic nematode known as hookworm. It infects the intestines of humans and animals. Answer: Hookworm.

4. Single Correct Answer MCQ: Pinctada produces:
Options:
A. Hookworm
B. Pearl oyster
C. Portuguese Man of War
D. Living fossil

Explanation: Pinctada is a marine bivalve that produces natural pearls. Answer: Pearl oyster.

5. Single Correct Answer MCQ: Which organism is a living fossil?
Options:
A. Physalia
B. Limulus
C. Ancylostoma
D. Pinctada

Explanation: Limulus, the horseshoe crab, has shown minimal evolutionary changes over millions of years, earning it the title of living fossil. Answer: Limulus.

6. Single Correct Answer MCQ: Portuguese Man of War belongs to:
Options:
A. Limulus
B. Pinctada
C. Physalia
D. Ancylostoma

Explanation: The marine colonial cnidarian Physalia is commonly known as the Portuguese Man of War. Answer: Physalia.

7. Assertion-Reason MCQ:
Assertion (A): Ancylostoma is a hookworm.
Reason (R): It belongs to parasitic nematodes that infect intestines.
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: Ancylostoma is indeed a hookworm, and it infects the intestines, making the reason correct. Both assertion and reason are true and logically connected. Answer: Both A and R true, R correct explanation.

8. Matching Type MCQ:
List I: a. Physalia b. Limulus c. Ancylostoma d. Pinctada
List II: i. Hookworm ii. Pearl oyster iii. Portuguese Man of War iv. Living fossil
Options:
A. a-iii, b-iv, c-i, d-ii
B. a-iv, b-iii, c-ii, d-i
C. a-i, b-ii, c-iii, d-iv
D. a-ii, b-i, c-iv, d-iii

Explanation: Physalia = Portuguese Man of War, Limulus = Living fossil, Ancylostoma = Hookworm, Pinctada = Pearl oyster. Answer: a-iii, b-iv, c-i, d-ii.

9. Fill in the Blanks MCQ: The parasitic nematode that infects intestines is _______.
Options:
A. Physalia
B. Limulus
C. Ancylostoma
D. Pinctada

Explanation: Ancylostoma is a hookworm, a parasitic nematode infecting the intestines of humans and animals. Answer: Ancylostoma.

10. Choose the correct statements MCQ:
Options:
A. Physalia is Portuguese Man of War
B. Limulus is a living fossil
C. Ancylostoma is a hookworm
D. Pinctada is a pearl oyster
Select:
1. A, B, C
2. A, C, D
3. A, B, C, D
4. B, C, D

Explanation: All statements correctly match organisms to their description: Physalia = Portuguese Man of War, Limulus = Living fossil, Ancylostoma = Hookworm, Pinctada = Pearl oyster. Answer: A, B, C, D.

S0ubtopic: Bone Adaptations in Vertebrates

• Hollow bones: Bones with internal cavities, reducing weight for flight.

• Pneumatic bones: Air-filled bones in birds connected to respiratory system.

• Long bones: Bones longer than wide, provide support and mobility.

• Hemidactylus: Terrestrial lizard with solid bones.

• Macropus: Kangaroo with solid hopping bones.

• Ornithorhynchus: Platypus with solid aquatic bones.

• Neophron: Vulture with hollow and pneumatic long bones aiding flight.

• Pneumatization: Process of air-filling bones in birds.

• Vertebrates: Animals with backbone and varied skeletal structures.

• Osteology: Study of bones and their morphology.

• Avian adaptations: Hollow bones reduce skeletal weight for efficient flight.

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 skeletal weight and aid flight. Hemidactylus, Macropus, and Ornithorhynchus have solid bones suited for terrestrial or aquatic locomotion. Answer: Neophron.

1. Single Correct Answer MCQ: Hollow bones are primarily found in which class of animals?
Options:
A. Mammals
B. Birds
C. Reptiles
D. Amphibians

Explanation: Birds possess hollow bones that reduce skeletal weight, allowing efficient flight. Mammals, reptiles, and amphibians typically 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 to aid breathing 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 lizard with solid bones supporting ground movement. Birds like 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 to reduce weight, while terrestrial vertebrates rely on solid long bones. Answer: Weight support and movement.

5. Single Correct Answer MCQ: Pneumatization in bones is a characteristic of:
Options:
A. Reptiles
B. Birds
C. Amphibians
D. Mammals

Explanation: Pneumatization refers to air-filled bones seen in birds, which reduces skeletal weight and facilitates flight. Other classes of animals typically have solid bones. Answer: Birds.

6. Single Correct Answer MCQ: Which type of bone reduces overall body weight in flying animals?
Options:
A. Short bones
B. Hollow bones
C. Solid bones
D. Irregular bones

Explanation: Hollow bones reduce skeletal weight in birds, enhancing flight efficiency. Solid, short, or 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 that reduce weight for flight. They do not store fat; this 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. Correct matching: a-i, b-ii, c-iii, d-iv. 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 skeletal weight, facilitating flight in birds. Swimming, burrowing, or running animals typically 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: A, C, D. Answer: A, C, D.

Topic: Structural Organisation in Animals

Subtopic: Comparative Anatomy of Animal Phyla

• Metamerism: Segmentation of the body into repeated units, characteristic of annelids.

• Canal system: Water-conducting system in sponges (Porifera) for filter-feeding.

• Comb plates: Ciliary plates used for locomotion in ctenophores.

• Cnidoblasts: Specialized stinging cells in cnidarians used for defense and prey capture.

• Coelenterata: Phylum including cnidarians such as jellyfish, corals, and hydra.

• Ctenophora: Phylum of comb jellies, characterized by comb plates for movement.

• Annelida: Segmented worms exhibiting metamerism, such as earthworms and leeches.

• Porifera: Sponges with a porous body and canal system for water circulation.

• Segmentation: Division of body into repeated segments, aiding locomotion and specialization.

• Stinging Cells: Cnidoblasts used to capture prey or defense in aquatic animals.

• Ciliary Locomotion: Movement using coordinated cilia, as seen in comb plates of ctenophores.

Lead Question - 2021

Match List - I with List - II
List - I List - II
(a) Metamerism (i) Coelenterata
(b) Canal system (ii) Ctenophora
(c) Comb plates (iii) Annelida
(d) Cnidoblasts (iv) Porifera
Choose the correct answer from the options given below:

1. (a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)
2. (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i)
3. (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)
4. (a)-(iv), (b)-(iii), (c)-(i), (d)-(ii)

Explanation: Metamerism is seen in annelids, canal system in sponges, comb plates in ctenophores, and cnidoblasts in cnidarians. Correct matching is (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i). This reflects structural and functional adaptations in different animal phyla. Answer: (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i).

1. Single Correct Answer MCQ: Which phylum exhibits metamerism?
Options:
A. Porifera
B. Ctenophora
C. Annelida
D. Coelenterata

Explanation: Annelida are segmented worms with repeated body units, a feature called metamerism, aiding locomotion and specialization. Other phyla lack this segmentation. Answer: Annelida.

2. Single Correct Answer MCQ: The canal system is characteristic of:
Options:
A. Ctenophora
B. Porifera
C. Annelida
D. Coelenterata

Explanation: Porifera have a water-conducting canal system for filter-feeding. Other phyla do not have such a system. Answer: Porifera.

3. Single Correct Answer MCQ: Comb plates are used for locomotion in:
Options:
A. Cnidaria
B. Ctenophora
C. Porifera
D. Annelida

Explanation: Ctenophora possess comb plates made of cilia for locomotion, unlike other phyla that use muscles or body contractions. Answer: Ctenophora.

4. Single Correct Answer MCQ: Cnidoblasts are found in:
Options:
A. Coelenterata
B. Ctenophora
C. Porifera
D. Annelida

Explanation: Cnidoblasts are stinging cells in cnidarians (Coelenterata) used for prey capture and defense. Other phyla do not have cnidoblasts. Answer: Coelenterata.

5. Single Correct Answer MCQ: Segmentation of body units is called:
Options:
A. Canal system
B. Metamerism
C. Comb plates
D. Cnidoblasts

Explanation: Metamerism refers to the segmentation of the body into repeated units, characteristic of annelids. Answer: Metamerism.

6. Single Correct Answer MCQ: Which phylum uses ciliary locomotion?
Options:
A. Annelida
B. Ctenophora
C. Porifera
D. Coelenterata

Explanation: Ctenophora move using comb plates, which are rows of cilia, allowing them to swim efficiently in water. Answer: Ctenophora.

7. Assertion-Reason MCQ:
Assertion (A): Porifera possess a canal system for water circulation.
Reason (R): The canal system enables filter-feeding and nutrient transport.
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: Porifera have a canal system which allows water to flow through their body for filter-feeding and nutrient transport. The reason correctly explains the assertion. Answer: Both A and R true, R correct explanation.

8. Matching Type MCQ:
Column I: 1. Metamerism 2. Canal system 3. Comb plates 4. Cnidoblasts
Column II: A. Porifera B. Annelida C. Coelenterata D. Ctenophora
Options:
A. 1-B, 2-A, 3-D, 4-C
B. 1-B, 2-D, 3-A, 4-C
C. 1-D, 2-A, 3-B, 4-C
D. 1-B, 2-A, 3-C, 4-D

Explanation: Correct matching: Metamerism – Annelida, Canal system – Porifera, Comb plates – Ctenophora, Cnidoblasts – Coelenterata. Answer: 1-B, 2-A, 3-D, 4-C.

9. Fill in the Blank MCQ: ________ are stinging cells used for prey capture in cnidarians.
Options:
A. Comb plates
B. Cnidoblasts
C. Canal system
D. Metameres

Explanation:

Subtopic: Insect Classification

• Muscidae: Family of true flies including common houseflies.

• Housefly: Musca domestica, an insect commonly found near human habitations.

• Grasshopper: Insect of order Orthoptera with jumping hind legs.

• Cockroach: Insect of order Blattodea, nocturnal and scavenger.

• Firefly: Insect of order Coleoptera that produces light via bioluminescence.

• Diptera: Order of insects with a single pair of wings and halteres.

• Haltere: Reduced hind wings in Diptera used for balance during flight.

• Entomology: Study of insects.

• Insect Classification: Systematic arrangement of insects into orders, families, genera, and species.

• Scavenger: Organism that feeds on decaying organic matter.

• Bioluminescence: Emission of light by living organisms like fireflies.

Lead Question - 2021

Which one of the following belongs to the family Muscidae?

Options:
A. Grasshopper
B. Cockroach
C. Housefly
D. Firefly

Explanation: The family Muscidae belongs to order Diptera and includes true flies such as the common housefly (Musca domestica). Grasshoppers belong to Orthoptera, cockroaches to Blattodea, and fireflies to Coleoptera. Answer: Housefly.

1. Which order does the housefly belong to?
Options:
A. Coleoptera
B. Diptera
C. Orthoptera
D. Blattodea

Explanation: The housefly is classified under order Diptera characterized by a single pair of wings and halteres for balance. Other insects belong to different orders. Answer: Diptera.

2. Which of the following has halteres?
Options:
A. Cockroach
B. Housefly
C. Grasshopper
D. Firefly

Explanation: Halteres are reduced hind wings present in Diptera for stability in flight. The housefly, a true fly, possesses halteres. Cockroaches, grasshoppers, and fireflies lack halteres. Answer: Housefly.

3. Which insect is known for bioluminescence?
Options:
A. Grasshopper
B. Cockroach
C. Firefly
D. Housefly

Explanation: Fireflies produce light through bioluminescence for communication and mating. Houseflies, grasshoppers, and cockroaches do not emit light. Answer: Firefly.

4. Cockroaches belong to which order?
Options:
A. Coleoptera
B. Diptera
C. Orthoptera
D. Blattodea

Explanation: Cockroaches are classified under order Blattodea, known for their scavenging behavior and nocturnal habits. Other options belong to different insect orders. Answer: Blattodea.

5. Which insect has strong hind legs for jumping?
Options:
A. Cockroach
B. Housefly
C. Grasshopper
D. Firefly

Explanation: Grasshoppers possess enlarged hind legs adapted for jumping, a distinguishing feature of order Orthoptera. Houseflies, cockroaches, and fireflies do not have this adaptation. Answer: Grasshopper.

6. Diptera insects are characterized by:
Options:
A. Two pairs of wings
B. One pair of wings and halteres
C. No wings
D. Strong jumping legs

Explanation: In order Diptera, insects have a single pair of wings and halteres, aiding in flight stability. This distinguishes them from other orders with two pairs of wings or no wings. Answer: One pair of wings and halteres.

7. Assertion-Reason:
Assertion (A): Housefly belongs to Muscidae.
Reason (R): Muscidae is a family in order Diptera.
Options:
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 is true, R is false
D. A is false, R is true

Explanation: The housefly is part of the family Muscidae, which falls under order Diptera. The reason correctly explains the assertion. Answer: Both A and R are true, R is correct explanation.

8. Match the following:
Column I: 1. Housefly 2. Cockroach 3. Grasshopper 4. Firefly
Column II: A. Blattodea B. Coleoptera C. Orthoptera D. Diptera
Options:
A. 1-D, 2-A, 3-C, 4-B
B. 1-A, 2-B, 3-C, 4-D
C. 1-B, 2-C, 3-A, 4-D
D. 1-C, 2-D, 3-B, 4-A

Explanation: Correct matching: Housefly – Diptera (D), Cockroach – Blattodea (A), Grasshopper – Orthoptera (C), Firefly – Coleoptera (B). Answer: 1-D, 2-A, 3-C, 4-B.

9. Fill in the blank: The common housefly is scientifically named _______.
Options:
A. Musca domestica
B. Luciola cruciata
C. Periplaneta americana
D. Acrida viridissima

Explanation: The common housefly is scientifically known as Musca domestica, a member of the family Muscidae under order Diptera. Other species belong to different orders. Answer: Musca domestica.

10. Choose the correct statements:
1. Muscidae includes houseflies.
2. Cockroaches are in Orthoptera.
3. Fireflies produce light.
Options:
A. 1 and 3 only
B. 1 and 2 only
C. 2 and 3 only
D. 1, 2, and 3

Explanation: Statements 1 and 3 are correct. Muscidae includes houseflies, and fireflies produce light (bioluminescence). Cockroaches are in order Blattodea, not Orthoptera. Answer: 1 and 3 only.

Chapter: Chordates
Topic: General Characteristics of Chordates
Subtopic: Notochord and Vertebral Column

Keyword Definitions:

• Chordates: Animals possessing a notochord, dorsal hollow nerve cord, pharyngeal slits, endostyle, and post-anal tail at some life stage.

• Vertebrates: Chordates with a vertebral column replacing the notochord in adults.

• Notochord: Flexible rod-like structure providing axial support, present in all chordates at some stage.

• Vertebral column: Series of vertebrae replacing notochord in most vertebrates.

• Dorsal hollow nerve cord: Tubular nerve cord running along the back.

• Pharyngeal slits: Openings in pharynx used for filter-feeding or respiration.

• Endostyle: Ciliated groove in pharynx producing mucus for feeding, present in non-vertebrate chordates.

• Post-anal tail: Extension of body past the anus, aiding in locomotion.

• Adult chordates: Stage where vertebral column may replace notochord in vertebrates.

• Ventral: Relating to the front or belly side of an organism.

Lead Question - 2020 (COVID Reexam)

All vertebrates are chordates but all chordates are not vertebrates, why?

1. Notochord is replaced by a vertebral column in adult of some chordates.
2. Ventral hollow nerve cord remains throughout life in some chordates.
3. All chordates possess a vertebral column.
4. All chordates possess notochord throughout their life.

Explanation: All vertebrates belong to chordates because they exhibit a notochord during embryonic stages. In vertebrates, the notochord is replaced by a vertebral column in adults. Non-vertebrate chordates retain the notochord without developing vertebrae. Hence, the correct answer is option (1) Notochord is replaced by a vertebral column in adult of some chordates.

Guessed Questions:

1. Which of the following chordates lacks a vertebral column?
(1) Amphibians
(2) Reptiles
(3) Lancelets
(4) Mammals

Explanation: Lancelets (Amphioxus) are non-vertebrate chordates that retain the notochord throughout life without developing a vertebral column. Amphibians, reptiles, and mammals are vertebrates. Correct answer is option (3) Lancelets.

2. In vertebrates, the notochord is replaced by:
(1) Dorsal hollow nerve cord
(2) Vertebral column
(3) Endostyle
(4) Pharyngeal slits

Explanation: Vertebrates develop a vertebral column that replaces the notochord in adults, providing rigid axial support. The dorsal hollow nerve cord persists as the central nervous system, endostyle aids in feeding, and pharyngeal slits assist in respiration. Correct answer is option (2) Vertebral column.

3. Which feature is present in all chordates at some stage?
(1) Vertebral column
(2) Notochord
(3) Paired fins
(4) Lungs

Explanation: All chordates possess a notochord during some life stage, even if replaced by vertebral column in adults. Vertebral column, paired fins, and lungs are specific to vertebrates. Correct answer is option (2) Notochord.

4. Dorsal hollow nerve cord is located:
(1) Ventral side
(2) Dorsal side
(3) Lateral side
(4) Inside the notochord

Explanation: In chordates, the nerve cord is tubular and dorsal, lying above the notochord. This differentiates chordates from other phyla with ventral nerve cords. Correct answer is option (2) Dorsal side.

5. Which of the following is a non-vertebrate chordate?
(1) Shark
(2) Frog
(3) Ascidians
(4) Lizard

Explanation: Ascidians (sea squirts) are non-vertebrate chordates retaining notochord in larval stage but losing it in adults. Sharks, frogs, and lizards are vertebrates. Correct answer is option (3) Ascidians.

6. Which chordate has notochord in adult stage without vertebral column?
(1) Amphioxus
(2) Mammal
(3) Bird
(4) Fish

Explanation: Amphioxus retains the notochord throughout life, unlike mammals, birds, and fish where it is replaced by vertebral column. It is a model organism for studying primitive chordates. Correct answer is option (1) Amphioxus.

7. Assertion (A): Vertebrates are chordates.
Reason (R): Vertebrates have a notochord during embryonic development.
(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: All vertebrates are chordates because they possess a notochord in early embryonic stages, which is later replaced by vertebral column. Both assertion and reason are true, and reason correctly explains the assertion. Correct answer is option (1).

8. Fill in the blanks:
The ______ provides axial support in all chordates during some stage of life.
(1) Vertebral column
(2) Notochord
(3) Dorsal nerve cord
(4) Endostyle

Explanation: The notochord is a flexible rod providing axial support in all chordates at some life stage. Vertebral column replaces it in vertebrates. Dorsal nerve cord and endostyle serve other functions. Correct answer is option (2) Notochord.

9. Match the following:
(a) Amphioxus - (i) Vertebrate
(b) Shark - (ii) Non-vertebrate
(c) Frog - (iii) Vertebrate
(d) Sea squirt - (iv) Non-vertebrate

Options:
(1) a-(ii), b-(i), c-(iii), d-(iv)
(2) a-(i), b-(ii), c-(iii), d-(iv)
(3) a-(iv), b-(i), c-(ii), d-(iii)
(4) a-(ii), b-(iii), c-(i), d-(iv)

Explanation: Amphioxus and sea squirts are non-vertebrate chordates. Shark and frog are vertebrates. Correct matching is option (1).

10. Choose the correct statements:
(1

Chapter: Chordates
Topic: Classifications of Vertebrates
Subtopic: Distinctive Features of Organisms

Keyword Definitions:

• Aptenodytes: Genus of penguins, flightless birds adapted to cold environments.

• Pteropus: Genus of large fruit bats, also called flying foxes, capable of flight.

• Pterophyllum: Genus of freshwater fish, commonly known as angelfish, laterally compressed.

• Petromyzon: Genus of jawless fishes, commonly known as lampreys.

• Penguin: Flightless bird adapted to aquatic life.

• Flying fox: Large fruit-eating bat capable of flying.

• Angelfish: Freshwater ornamental fish, laterally compressed with long fins.

• Lamprey: Jawless fish with suction-cup mouth, parasitic on other fish.

• Genus: Taxonomic rank above species, grouping closely related organisms.

• Flightless bird: Bird species that has lost the ability to fly but adapted to other habitats.

Lead Question - 2020 (COVID Reexam)

Match the following columns and select the correct option:

Column - I - Column - II
(a) Aptenodytes - (i) Flying fox
(b) Pteropus - (ii) Angel fish
(c) Pterophyllum - (iii) Lamprey
(d) Petromyzon - (iv) Penguin

1. (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i)
2. (a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)
3. (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)
4. (a)-(ii), (b)-(i), (c)-(iv), (d)-(iii)

Explanation: Aptenodytes belongs to penguins (flightless birds adapted to cold). Pteropus is the flying fox, a large fruit bat. Pterophyllum is angelfish, a freshwater ornamental fish. Petromyzon is lamprey, a jawless fish. Hence, correct matching is option (3) (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii).

Guessed Questions:

1. Which organism is a flightless bird?
(1) Pteropus
(2) Aptenodytes
(3) Pterophyllum
(4) Petromyzon

Explanation: Aptenodytes belongs to penguins, which are flightless birds adapted to cold aquatic habitats. Pteropus is a bat, Pterophyllum is a fish, and Petromyzon is a jawless fish. Correct answer is option (2) Aptenodytes.

2. Which organism is a flying mammal?
(1) Aptenodytes
(2) Petromyzon
(3) Pteropus
(4) Pterophyllum

Explanation: Pteropus is a genus of large fruit-eating bats called flying foxes capable of flight. Aptenodytes is flightless, Pterophyllum is a fish, and Petromyzon is jawless fish. Correct answer is option (3) Pteropus.

3. Which organism is a freshwater fish?
(1) Pterophyllum
(2) Petromyzon
(3) Aptenodytes
(4) Pteropus

Explanation: Pterophyllum is an angelfish, a freshwater fish commonly found in aquariums. Petromyzon is a jawless fish, but mostly parasitic in other fish, not typical freshwater aquarium fish. Correct answer is option (1) Pterophyllum.

4. Petromyzon is classified as:
(1) Jawless fish
(2) Bony fish
(3) Cartilaginous fish
(4) Amphibian

Explanation: Petromyzon belongs to lampreys, which are jawless fish (Agnatha) with suction-cup mouths. They lack paired fins and true jaws. Correct answer is option (1) Jawless fish.

5. Match the following:
(a) Pterophyllum - (i) Bat
(b) Pteropus - (ii) Fish
(c) Aptenodytes - (iii) Bird
(d) Petromyzon - (iv) Lamprey

Options:
(1) a-(ii), b-(i), c-(iii), d-(iv)
(2) a-(i), b-(ii), c-(iv), d-(iii)
(3) a-(iii), b-(iv), c-(i), d-(ii)
(4) a-(iv), b-(iii), c-(ii), d-(i)

Explanation: Pterophyllum is fish, Pteropus is bat, Aptenodytes is bird (penguin), and Petromyzon is lamprey. Correct matching is option (1).

6. Which of the following is adapted to cold aquatic environments?
(1) Pteropus
(2) Aptenodytes
(3) Pterophyllum
(4) Petromyzon

Explanation: Aptenodytes penguins are adapted to cold aquatic environments with specialized feathers and insulation. Other organisms do not inhabit cold habitats. Correct answer is option (2) Aptenodytes.

7. Assertion (A): Pteropus is capable of powered flight.
Reason (R): It is a large fruit-eating bat with developed wings.
(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: Pteropus, a flying fox, is a large fruit bat capable of powered flight. Its wings are adapted for flying. Both assertion and reason are true, and reason correctly explains the assertion. Correct answer is option (1).

8. Fill in the blanks:
_______ is a jawless fish with a suction-cup mouth.
(1) Aptenodytes
(2) Petromyzon
(3) Pteropus
(4) Pterophyllum

Explanation: Petromyzon is a lamprey, a jawless fish with a suction-cup mouth, parasitic on other fishes. Aptenodytes is a bird, Pteropus a bat, and Pterophyllum a fish with jaws. Correct answer is option (2) Petromyzon.

9. Which of the following is an ornamental freshwater fish?
(1) Aptenodytes
(2) Pterophyllum
(3) Pteropus
(4) Petromyzon

Explanation: Pterophyllum is angelfish, commonly kept in aquariums as an ornamental freshwater fish. Aptenodytes is a penguin, Pteropus a bat, and Petromyzon a lamprey. Correct answer is option (2) Pterophyllum.

Topic: Non-chordates and Chordates
Subtopic: Phylum Characteristics

Keyword Definitions:

• Platyhelminthes: Flatworms, acoelomate, triploblastic, bilaterally symmetrical animals.

• Echinoderms: Marine animals with pentaradial symmetry, coelomate, and indirect development.

• Hemichordates: Worm-like deuterostomes with a dorsal nerve cord and pharyngeal gill slits.

• Aves: Warm-blooded, feathered vertebrates with direct development and endoskeleton.

• Direct development: Development without larval stage.

• Indirect development: Development involving larval stage.

• Bilateral symmetry: Body plan with left and right halves mirror images.

• Radial symmetry: Body plan with symmetry around a central axis.

• Cylindrical body: Elongated tube-like shape without segmentation.

• Segmentation: Division of body into repeated units or metameres.

Lead Question - 2020 (COVID Reexam)

Match the following group of organisms with their respective distinctive characteristics and select the correct option:

Organisms - Characteristics
(a) Platyhelminthes - Cylindrical body with no segmentation
(b) Echinoderms - Warm blooded animals with direct development
(c) Hemichordates - Bilateral symmetry with incomplete digestive system
(d) Aves - Radial symmetry with indirect development

1. (a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)
2. (a)-(ii), (b)-(iii), (c)-(iv), (d)-(i)
3. (a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)
4. (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)

Explanation: Platyhelminthes are flatworms, not cylindrical, acoelomate, bilaterally symmetrical, thus option (a) should match incomplete digestive system. Echinoderms are marine, radially symmetrical with indirect development. Hemichordates are worm-like with cylindrical body. Aves are warm-blooded vertebrates with direct development. Hence, correct answer is option (4) (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv).

Guessed Questions:

1. Which of the following is acoelomate?
(1) Platyhelminthes
(2) Echinoderms
(3) Hemichordates
(4) Aves

Explanation: Platyhelminthes are acoelomate flatworms with no body cavity. Echinoderms, hemichordates, and aves are coelomates. This allows Platyhelminthes to have simple body organization. Correct answer is option (1) Platyhelminthes.

2. Which group shows radial symmetry?
(1) Platyhelminthes
(2) Echinoderms
(3) Hemichordates
(4) Aves

Explanation: Echinoderms exhibit pentaradial symmetry as adults, although larvae are bilaterally symmetrical. This symmetry supports their sessile or slow-moving lifestyle. Platyhelminthes, hemichordates, and aves exhibit bilateral symmetry. Correct answer is option (2) Echinoderms.

3. Which of the following organisms is warm-blooded?
(1) Platyhelminthes
(2) Echinoderms
(3) Hemichordates
(4) Aves

Explanation: Aves are endothermic or warm-blooded vertebrates that maintain a constant body temperature. Other groups such as platyhelminthes, echinoderms, and hemichordates are cold-blooded. Correct answer is option (4) Aves.

4. Which organisms have indirect development?
(1) Platyhelminthes
(2) Echinoderms
(3) Hemichordates
(4) Aves

Explanation: Echinoderms undergo indirect development with a larval stage before transforming into adults. Aves show direct development. Platyhelminthes and hemichordates also exhibit direct or simpler development. Correct answer is option (2) Echinoderms.

5. The body of hemichordates is:
(1) Flattened
(2) Segmented
(3) Cylindrical
(4) Radially symmetrical

Explanation: Hemichordates are worm-like animals with cylindrical, unsegmented bodies and bilateral symmetry. They possess a pharyngeal gill slit and dorsal nerve cord. Correct answer is option (3) Cylindrical.

6. Which of the following is bilaterally symmetrical with incomplete digestive system?
(1) Aves
(2) Platyhelminthes
(3) Echinoderms
(4) Hemichordates

Explanation: Platyhelminthes are bilaterally symmetrical, triploblastic, acoelomate animals with an incomplete digestive system, meaning they have only one opening. Echinoderms, aves, and hemichordates have complete digestive tracts. Correct answer is option (2) Platyhelminthes.

7. Assertion (A): Aves have direct development.
Reason (R): Their eggs contain sufficient yolk for embryonic growth.
(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: Aves develop directly without larval stages, supported by nutrient-rich yolk in eggs. Hence, both assertion and reason are true, and reason correctly explains the assertion. Correct answer is option (1).

8. Match the following:
List I - Organism
(a) Nereis
(b) Starfish
(c) Saccoglossus
(d) Pigeon
List II - Feature
(i) Coelomate, segmented worm
(ii) Radial symmetry, indirect development
(iii) Hemichordate
(iv) Warm-blooded vertebrate

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-(i), d-(ii)

Explanation: Nereis is segmented coelomate, starfish exhibits radial symmetry with indirect development, Saccoglossus is hemichordate, and pigeon is warm-blooded vertebrate. Correct answer is option (1).

9. Fill in the blanks:
The characteristic symmetry of echinoderms in adult stage is ______.
(1) Bilateral
(2) Radial
(3) Asymmetrical
(4) Spiral

Explanation: Adult echinoderms show pentaradial symmetry which is a type of radial symmetry, though larvae are bilaterally symmetrical. This adaptation helps in sedentary or slow-moving lifestyle. Correct answer is option (2) Radial.

10. Choose the correct statements:
(1) Aves are warm-blooded
(2) Platyhelminthes are coelomate
(3) Echinoderms show indirect development
(4) Hemichordates have cylindrical body

Topic: Non-chordates
Subtopic: Phylum Annelida

Keyword Definitions:

• Triploblastic: Organisms with three germ layers – ectoderm, mesoderm, and endoderm.

• Coelom: Fluid-filled true body cavity lined by mesoderm.

• Segmentation: Division of body into repetitive units called metameres.

• Bilateral symmetry: Body plan with left and right halves mirror images.

• Annelida: Vermiform, segmented worms with closed circulatory system.

• Acoelomate: Animals lacking a body cavity.

Lead Question - 2020 (COVID Reexam)

Which of the following options does correctly represent the characteristic features of phylum Annelida?

(1) Triploblastic, unsegmented body, and bilaterally symmetrical.
(2) Triploblastic, a segmented body, and bilaterally symmetrical.
(3) Triploblastic, flattened body, and acoelomate condition.
(4) Diploblastic, mostly marine and radially symmetrical.

Explanation: Annelids are triploblastic, bilaterally symmetrical, coelomate animals with true segmentation called metamerism. They have a closed circulatory system and nephridia for excretion. Their segmented body clearly distinguishes them from flatworms and cnidarians. Therefore, the correct answer is option (2) Triploblastic, a segmented body, and bilaterally symmetrical.

Guessed Questions:

1. Which of the following is a characteristic feature of Annelids?
(1) Radial symmetry
(2) Segmentation
(3) Diploblastic condition
(4) Pseudocoelom

Explanation: Annelids possess true metameric segmentation where their body is divided into repetitive segments. This segmentation is both external and internal, providing better locomotion and specialization of body parts. Hence, the correct answer is option (2) Segmentation.

2. Which of the following shows closed circulatory system?
(1) Arthropods
(2) Annelids
(3) Molluscs
(4) Echinoderms

Explanation: Annelids are among the first animals to evolve a closed circulatory system, where blood flows through vessels and not in body cavities. This allows efficient transport of gases and nutrients. Therefore, the correct answer is option (2) Annelids.

3. The excretory organs in annelids are called:-
(1) Malpighian tubules
(2) Flame cells
(3) Nephridia
(4) Green glands

Explanation: Annelids possess nephridia as their excretory structures which help remove nitrogenous wastes and maintain osmoregulation. Flame cells are seen in flatworms, Malpighian tubules in insects, and green glands in crustaceans. Thus, the correct answer is option (3) Nephridia.

4. Which of the following is a dioecious annelid?
(1) Earthworm
(2) Leech
(3) Nereis
(4) Hirudinaria

Explanation: Nereis, a marine annelid, is dioecious and sexually reproduces with external fertilization. In contrast, earthworms and leeches are hermaphroditic. Hence, the correct answer is option (3) Nereis.

5. The body cavity of annelids is derived from:-
(1) Blastocoel
(2) Archenteron
(3) Schizocoely
(4) Enterocoely

Explanation: Annelids exhibit a true coelom formed by schizocoely, where the mesoderm splits to form the coelomic cavity. This coelom acts as a hydrostatic skeleton aiding locomotion. Thus, the correct answer is option (3) Schizocoely.

6. Which feature distinguishes annelids from nematodes?
(1) Bilateral symmetry
(2) Triploblastic condition
(3) Segmentation
(4) Pseudocoelom

Explanation: Annelids are coelomates with true segmentation, whereas nematodes are pseudocoelomates without segmentation. Hence, the distinguishing feature is segmentation. Correct answer is option (3) Segmentation.

7. Assertion (A): Earthworm shows metameric segmentation.
Reason (R): Segments are externally visible but internally absent.
(1) Both A and R true, R explains A
(2) Both A and R true, R does not explain A
(3) A true but R false
(4) A false but R true

Explanation: Earthworms show true metamerism where segmentation is both external and internal, seen in septa and organ arrangement. Hence, assertion is true but reason is false. Correct answer is option (3).

8. Match the following:
List I - Organism
(a) Nereis
(b) Earthworm
(c) Hirudinaria
(d) Leech
List II - Feature
(i) Dioecious
(ii) Hermaphroditic
(iii) Setae absent
(iv) Parasitic

Options:
(1) a-(i), b-(ii), c-(iii), d-(iv)
(2) a-(iv), b-(iii), c-(ii), d-(i)
(3) a-(ii), b-(iv), c-(i), d-(iii)
(4) a-(iii), b-(i), c-(iv), d-(ii)

Explanation: Nereis is dioecious, earthworm hermaphroditic, Hirudinaria lacks setae, and leech is parasitic. Therefore, the correct answer is option (1).

9. Fill in the blanks:
In annelids, locomotion occurs due to action of ______.
(1) Setae and muscles
(2) Cilia
(3) Flagella
(4) Parapodia only

Explanation: Annelid locomotion occurs due to coordinated action of circular and longitudinal muscles along with setae or parapodia. These structures work against the hydrostatic skeleton to produce movement. Correct answer is option (1) Setae and muscles.

10. Choose the correct statements about annelids:
(1) They are pseudocoelomates
(2) They exhibit radial symmetry
(3) They are triploblastic and coelomate
(4) Their segmentation is only external

Explanation: Annelids are triploblastic, bilaterally symmetrical, coelomate animals with true segmentation. Segmentation is both external and internal, seen in septa and organ arrangement. Hence, the correct statement is option (3).

Topic: Chordata

Subtopic: Characteristics of Phylum Chordata

Keyword Definitions:

• Phylum Chordata – Group of animals with a notochord, dorsal hollow nerve cord, pharyngeal slits, post-anal tail, and endostyle at some stage.

• Notochord – A flexible rod-like structure providing support in chordates.

• Urochordata – Subphylum of chordates where notochord is present in tail region, mostly in larval form.

• Vertebrata – Subphylum of chordates with a vertebral column replacing the notochord in adults.

• Central nervous system – In chordates, it is dorsal, hollow, and extends along the body.

• Subphyla – Divisions within Chordata: Hemichordata, Tunicata (Urochordata), and Cephalochordata.

Lead Question - 2020

Which of the following statements are true for the phylum-Chordata?
(a) In Urochordata notochord extends from head to tail and it is present throughout their life.
(b) In Vertebrata notochord is present during the embryonic period only.
(c) Central nervous system is dorsal and hollow.
(d) Chordata is divided into 3 subphyla; Hemichordata, Tunicata and Cephalochordata.

(1) (a) and (b)
(2) (b) and (c)
(3) (d) and (c)
(4) (c) and (a)

Explanation: In Urochordata, the notochord is limited to the tail in larval stage and absent in adult, making statement (a) incorrect. In Vertebrata, notochord is present only embryonically (b), CNS is dorsal and hollow (c), and chordates are divided into 3 subphyla: Hemichordata, Tunicata, Cephalochordata (d). Correct answer is (2) (b) and (c).

1. Single Correct Answer: In vertebrates, the notochord is present:
(1) Throughout life
(2) During embryonic development only
(3) Only in tail region
(4) Not present at all

Explanation: Vertebrates replace the notochord with vertebral column in adults, so it is present only during embryonic development. Correct answer is (2).

2. Single Correct Answer: The central nervous system of chordates is:
(1) Ventral and solid
(2) Dorsal and hollow
(3) Dorsal and solid
(4) Ventral and hollow

Explanation: Chordates have a dorsal, hollow nerve cord forming the central nervous system. Correct answer is (2).

3. Single Correct Answer: Which of these is not a subphylum of Chordata?
(1) Hemichordata
(2) Tunicata
(3) Cephalochordata
(4) Mollusca

Explanation: Hemichordata, Tunicata, and Cephalochordata are subphyla of Chordata. Mollusca is a separate phylum. Correct answer is (4).

4. Assertion (A): Central nervous system in chordates is dorsal.
Reason (R): It runs along the dorsal side and is hollow.
(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: The CNS in chordates is dorsal and hollow, which explains statement A. Both Assertion and Reason are correct. Correct answer is (1).

5. Single Correct Answer: In Urochordata, notochord is present:
(1) Throughout life
(2) Only in larval tail
(3) In head region
(4) Not present at all

Explanation: Urochordata have a notochord limited to the tail in the larval stage; it disappears in adult. Correct answer is (2).

6. Single Correct Answer: Which of the following is a characteristic feature of chordates?
(1) Ventral nerve cord
(2) Post-anal tail
(3) Exoskeleton
(4) Radial symmetry

Explanation: Post-anal tail is a unique feature of chordates, along with notochord, dorsal hollow nerve cord, pharyngeal slits, and endostyle. Correct answer is (2).

7. Matching Type: Match the following:
a. Urochordata – i. Notochord in larval tail
b. Vertebrata – ii. Notochord embryonic
c. Cephalochordata – iii. Notochord entire life
d. CNS – iv. Dorsal hollow
(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: Urochordata has notochord in larval tail (a-i), vertebrates embryonic notochord (b-ii), Cephalochordata retains it throughout life (c-iii), CNS is dorsal hollow (d-iv). Correct answer is (1).

8. Fill in the blank: In vertebrates, the notochord is replaced by ______.
(1) Exoskeleton
(2) Vertebral column
(3) Dorsal hollow nerve cord
(4) Pharyngeal slits

Explanation: In vertebrates, the notochord is replaced by the vertebral column during development. Correct answer is (2).

9. Single Correct Answer: Cephalochordata shows notochord:
(1) Only in head
(2) Throughout life
(3) Only in larval stage
(4) Not present

Explanation: Cephalochordates retain the notochord throughout their life, providing support. Correct answer is (2).

10. Choose the correct statements:
(a) Vertebrates have notochord only in embryos
(b) CNS is dorsal and hollow
(c) Urochordata notochord is present throughout life
(d) Chordata divided into Hemichordata, Tunicata, Cephalochordata
(1) a, b only
(2) b, c only
(3) a, b, d only
(4) a, c, d only

Explanation: Vertebrates have embryonic notochord (a), CNS is dorsal hollow (b), Chordata divided into Hemichordata, Tunicata, Cephalochordata (d). Statement about Urochordata having lifelong notochord is incorrect. Correct answer is (3) a, b, d only.

Topic: Invertebrates and Vertebrates

Subtopic: Characteristics and Adaptations

Keyword Definitions:

• Gregarious – Living in groups or swarms, commonly seen in some insect pests.

• Polyphagous pest – Insect that feeds on multiple plant species causing agricultural damage.

• Radial symmetry – Body plan in which body parts are arranged around a central axis.

• Bilateral symmetry – Body plan with distinct left and right halves, typical in many animals.

• Book lungs – Respiratory organs in arachnids for gas exchange.

• Bioluminescence – Emission of light by living organisms like some marine animals.

Lead Question - 2020

Match the following columns and select the correct option.

Column-I Column-II
(a) Gregarious, polyphagous pest (i) Asterias
(b) Adult with radial symmetry and larva with bilateral symmetry (ii) Scorpion
(c) Book lungs (iii) Ctenoplana
(d) Bioluminescence (iv) Locusta

(A) a-iii, b-ii, c-i, d-iv
(B) a-ii, b-i, c-iii, d-iv
(C) a-i, b-iii, c-ii, d-iv
(D) a-iv, b-i, c-ii, d-iii

Explanation: Locusta is a gregarious, polyphagous pest (a-iv). Ctenoplana exhibits adult radial symmetry with larval bilateral symmetry (b-iii). Scorpion possesses book lungs (c-ii). Asterias exhibits bioluminescence (d-iii). Correct option is (D) a-iv, b-i, c-ii, d-iii. This matching demonstrates diverse adaptations in invertebrates.

1. Single Correct Answer: Which of the following exhibits book lungs?
(1) Scorpion
(2) Locusta
(3) Ctenoplana
(4) Asterias

Explanation: Book lungs are respiratory organs in arachnids for gas exchange. Scorpions possess book lungs. Correct answer is (1) Scorpion.

2. Single Correct Answer: Polyphagous pests are characterized by:
(1) Feeding on one plant species
(2) Feeding on multiple plant species
(3) Bioluminescence
(4) Radial symmetry

Explanation: Polyphagous pests consume several plant species, causing agricultural damage. Locusta is an example. Correct answer is (2) Feeding on multiple plant species.

3. Single Correct Answer: Which organism shows adult radial symmetry with larval bilateral symmetry?
(1) Locusta
(2) Scorpion
(3) Ctenoplana
(4) Asterias

Explanation: Ctenoplana exhibits adult radial symmetry while the larval stage is bilaterally symmetrical. Correct answer is (3) Ctenoplana.

4. Assertion (A): Locusta is a polyphagous pest.
Reason (R): Polyphagous pests feed on multiple plant species.
(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: Locusta feeds on multiple plant species, making it a polyphagous pest. Both Assertion and Reason are true, and R explains A. Correct answer is (1).

5. Single Correct Answer: Bioluminescence is exhibited by:
(1) Asterias
(2) Scorpion
(3) Locusta
(4) Ctenoplana

Explanation: Bioluminescence, the ability to emit light, is exhibited by certain marine organisms like Asterias. Correct answer is (1) Asterias.

6. Single Correct Answer: Which of these is a gregarious pest?
(1) Ctenoplana
(2) Locusta
(3) Scorpion
(4) Asterias

Explanation: Locusta forms large swarms and feeds on multiple crops, classifying it as a gregarious pest. Correct answer is (2) Locusta.

7. Match the organisms with their adaptations:
a. Locusta – i. Polyphagous pest
b. Ctenoplana – ii. Radial adult symmetry, bilateral larva
c. Scorpion – iii. Book lungs
d. Asterias – iv. Bioluminescence
(1) a-i, b-ii, c-iii, d-iv
(2) a-ii, b-i, c-iv, d-iii
(3) a-iv, b-iii, c-i, d-ii
(4) a-iii, b-iv, c-ii, d-i

Explanation: Locusta (a-i) is a polyphagous pest, Ctenoplana (b-ii) shows radial adult symmetry with bilateral larva, Scorpion (c-iii) has book lungs, and Asterias (d-iv) exhibits bioluminescence. Correct answer is (1).

8. Fill in the blank: The respiratory structure present in scorpions is ______.
(1) Trachea
(2) Gills
(3) Book lungs
(4) Lungs

Explanation: Scorpions possess book lungs for respiration, consisting of layered structures facilitating gas exchange. Correct answer is (3) Book lungs.

9. Single Correct Answer: Which animal exhibits bioluminescence in marine ecosystems?
(1) Locusta
(2) Asterias
(3) Ctenoplana
(4) Scorpion

Explanation: Asterias, a marine organism, emits light due to bioluminescence. This adaptation can aid in communication or predation. Correct answer is (2) Asterias.

10. Choose the correct statements:
(a) Locusta is a polyphagous pest
(b) Ctenoplana shows radial adult symmetry
(c) Scorpions possess book lungs
(d) Asterias exhibits bioluminescence
(1) a, b, c only
(2) a, c, d only
(3) b, c, d only
(4) a, b, c, d

Explanation: Locusta is polyphagous (a), Ctenoplana shows radial adult symmetry (b), Scorpion has book lungs (c), and Asterias exhibits bioluminescence (d). All statements are correct. Correct answer is (4) a, b, c, d.

Subtopic: Morphological Features of Fishes

• Gill slits: Openings in fishes used for respiration; cyclostomes have 6–15 pairs.

• Heterocercal caudal fin: Asymmetrical tail fin with vertebral column extending into upper lobe; typical of Chondrichthyes.

• Air bladder: Gas-filled sac in Osteichthyes for buoyancy control.

• Poison sting: Defensive organ present in some Chondrichthyes.

• Trygon: Stingray genus of Chondrichthyes with poison stings.

• Cyclostomes: Jawless fishes including lampreys and hagfishes with multiple gill slits.

• Chondrichthyes: Cartilaginous fishes including sharks, rays, and skates.

• Osteichthyes: Bony fishes with air bladder, scales, and paired fins.

• Caudal fin types: Tail fins vary: heterocercal in Chondrichthyes, homocercal in Osteichthyes.

• Buoyancy: Air bladder in bony fishes helps maintain position in water without energy.

• Defense mechanism: Poison stings in stingrays act as a protective adaptation.

Lead Question (2020): Match the following columns and select the correct option :

Column - I Column - II
(a) 6–15 pairs of gill slits
(b) Heterocercal caudal fin
(c) Air Bladder
(d) Poison sting

1. a-iv, b-ii, c-iii, d-i

2. a-i, b-iv, c-iii, d-ii

3. a-ii, b-iii, c-iv, d-i

4. a-iii, b-iv, c-i, d-ii

Explanation: The correct answer is 3. Cyclostomes have 6–15 pairs of gill slits (a-ii). Chondrichthyes exhibit heterocercal caudal fins (b-iii). Osteichthyes possess an air bladder for buoyancy (c-iv). Poison sting is characteristic of stingrays in Chondrichthyes (d-i). Correct matching highlights evolutionary adaptations of different fish groups.

Guessed MCQs:

1. Question 1: Which fish group has heterocercal caudal fins?
   A. Cyclostomes
   B. Chondrichthyes
   C. Osteichthyes
   D. Amphibians
   Explanation: The correct answer is B. Chondrichthyes, including sharks and rays, have heterocercal caudal fins with the vertebral column extending into the upper lobe, aiding in propulsion and maneuverability. Osteichthyes typically have homocercal fins.

2. Question 2: Cyclostomes include:
   A. Sharks and rays
   B. Lampreys and hagfishes
   C. Bony fishes
   D. Amphibians
   Explanation: The correct answer is B. Cyclostomes are jawless fishes such as lampreys and hagfishes with multiple gill slits (6–15 pairs). They lack paired fins and true jaws, unlike Chondrichthyes and Osteichthyes.

3. Question 3: Air bladder is present in:
   A. Cyclostomes
   B. Chondrichthyes
   C. Osteichthyes
   D. Amphibians
   Explanation: The correct answer is C. Osteichthyes have a gas-filled air bladder that regulates buoyancy, allowing them to maintain depth in water without swimming. Cartilaginous fishes do not possess air bladders.

4. Question 4: Poison stings are characteristic of:
   A. Sharks only
   B. Stingrays
   C. Lampreys
   D. Bony fishes
   Explanation: The correct answer is B. Poison stings are present in stingrays (Trygon), a type of Chondrichthyes. These defensive adaptations protect them from predators and are absent in bony fishes or cyclostomes.

5. Question 5: The number of gill slits in cyclostomes is:
   A. 1–3 pairs
   B. 6–15 pairs
   C. 2–4 pairs
   D. 16–20 pairs
   Explanation: The correct answer is B. Cyclostomes, including lampreys and hagfishes, possess 6–15 pairs of gill slits. This is an important distinguishing feature from Chondrichthyes and Osteichthyes.

6. Question 6: Heterocercal tail fin function:
   A. Buoyancy
   B. Propulsion
   C. Defense
   D. Respiration
   Explanation: The correct answer is B. Heterocercal caudal fins in Chondrichthyes provide thrust and lift during swimming. Air bladders handle buoyancy in bony fishes, not the tail fin.

7. Question 7: Assertion-Reason:
   Assertion (A): Osteichthyes have air bladders.
   Reason (R): Air bladders help maintain buoyancy in water.
   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
   Explanation: The correct answer is A. Osteichthyes possess air bladders, which regulate buoyancy allowing fish to maintain depth without continuous swimming, directly linking structure and function.

8. Question 8: Matching Type: Match fish feature with group:
   i. 6–15 gill slits - A. Cyclostomes
   ii. Heterocercal fin - B. Chondrichthyes
   iii. Air bladder - C. Osteichthyes
   iv. Poison sting - D. Chondrichthyes
   Choices:
   A. i-A, ii-B, iii-C, iv-D
   B. i-B, ii-A, iii-D, iv-C
   C. i-A, ii-C, iii-B, iv-D
   D. i-D, ii-C, iii-A, iv-B
   Explanation: The correct answer is A. Gill slit number identifies cyclostomes, heterocercal fins indicate Chondrichthyes, air bladder is characteristic of Osteichthyes, and poison sting is a feature of stingrays in Chondrichthyes.

9. Question 9: Fill in the Blanks: The gas-filled sac in bony fishes for buoyancy is called ________.
   A. Air bladder
   B. Swim fin
   C. Gill slit
   D. Heterocercal fin
   Explanation: The correct answer is A. The air bladder in Osteichthyes regulates buoyancy, allowing the fish to maintain position in water without swimming. It is absent in cartilaginous fishes.

10. Question 10: Choose the correct statements:
    i. Cyclostomes have multiple gill slits
    ii. Chondrichthyes have heterocercal fins
    iii. Osteichthyes possess air bladder
    iv. Poison sting is found in bony fishes
    A. i, ii, iii
    B. i, iv
    C. ii, iii, iv
    D. i, ii, iii, iv
    Explanation: The correct answer is A. Cyclostomes have multiple gill slits, Chondrichthyes have heterocercal fins, and Osteichthyes have air bladder. Poison sting occurs in stingrays (Chondrichthyes), not in bony fishes.

Topic: Animal Symmetry and Body Cavities
Subtopic: Acoelomate and Bilateral Animals

• Bilaterally Symmetrical: Organisms with body plan divisible into mirror-image halves along a single plane.

• Acoelomate: Animals lacking a body cavity between the digestive tract and body wall.

• Aschelminthes: Pseudocoelomate invertebrates, often unsegmented worms with body cavity not fully lined with mesoderm.

• Annelida: Segmented coelomate worms like earthworms with true coelom and bilateral symmetry.

• Ctenophora: Radially symmetrical, gelatinous marine animals known as comb jellies.

• Platyhelminthes: Flatworms, acoelomate and bilaterally symmetrical, including planarians, tapeworms, and flukes.

• Symmetry: The arrangement of body parts in a regular pattern.

• Body Cavity (Coelom): Fluid-filled space between body wall and gut in coelomates.

• Pseudocoelomate: Animals with body cavity partially lined with mesoderm.

• Digestive Tract: Complete or incomplete alimentary canal in animals.

• Flatworm: Member of Platyhelminthes, exhibiting bilateral symmetry and no coelom.

Lead Question (2020): Bilaterally symmetrical and acoelomate animals are exemplified by:
Options:
1. Aschelminthes
2. Annelida
3. Ctenophora
4. Platyhelminthes

Explanation: Correct answer is 4. Platyhelminthes, or flatworms, are bilaterally symmetrical and lack a body cavity, making them acoelomate. Annelids are coelomate, Aschelminthes are pseudocoelomate, and Ctenophora are radially symmetrical.

1. Single Correct Answer MCQ:
Which of the following is acoelomate?
Options:
a. Annelida
b. Platyhelminthes
c. Nematoda
d. Arthropoda

Explanation: Correct answer is b. Platyhelminthes lack a body cavity between the gut and body wall, making them acoelomate, unlike coelomate Annelids and pseudocoelomate Nematodes.

2. Single Correct Answer MCQ:
Which phylum shows bilateral symmetry and true coelom?
Options:
a. Platyhelminthes
b. Annelida
c. Ctenophora
d. Porifera

Explanation: Correct answer is b. Annelids exhibit bilateral symmetry and possess a true coelom, differentiating them from acoelomate flatworms and radially symmetrical Ctenophora.

3. Single Correct Answer MCQ:
Radially symmetrical animals include:
Options:
a. Platyhelminthes
b. Ctenophora
c. Annelida
d. Nematoda

Explanation: Correct answer is b. Ctenophora exhibit radial symmetry, unlike bilaterally symmetrical flatworms and segmented worms.

4. Single Correct Answer MCQ:
Which of the following is pseudocoelomate?
Options:
a. Platyhelminthes
b. Nematoda
c. Annelida
d. Cnidaria

Explanation: Correct answer is b. Nematodes have a body cavity not fully lined by mesoderm, classifying them as pseudocoelomates, unlike acoelomate flatworms or coelomate Annelids.

5. Single Correct Answer MCQ:
Which phylum includes tapeworms and planarians?
Options:
a. Annelida
b. Platyhelminthes
c. Nematoda
d. Ctenophora

Explanation: Correct answer is b. Tapeworms and planarians are members of Platyhelminthes, characterized by acoelomate body and bilateral symmetry.

6. Single Correct Answer MCQ:
Which feature is absent in Platyhelminthes?
Options:
a. Digestive tract
b. Coelom
c. Bilateral symmetry
d. Nervous system

Explanation: Correct answer is b. Platyhelminthes are acoelomate and lack a true coelom. They possess bilateral symmetry, incomplete digestive tract, and a simple nervous system.

7. Assertion-Reason MCQ:
Assertion (A): Flatworms are acoelomate animals.
Reason (R): They possess a coelomic cavity lined with mesoderm.
Options:
a. Both A and R are true, R explains A
b. Both A and R are true, R does not explain A
c. A is true, R is false
d. A is false, R is true

Explanation: Correct answer is c. Flatworms are acoelomate, meaning they lack a coelomic cavity. The reason is false, as they do not possess a mesoderm-lined cavity.

8. Matching Type MCQ:
Match the phylum with body cavity type:
(a) Platyhelminthes - (i) Coelomate
(b) Annelida - (ii) Pseudocoelomate
(c) Nematoda - (iii) Acoelomate
Options:
1. a-iii, b-i, c-ii
2. a-i, b-ii, c-iii
3. a-ii, b-iii, c-i
4. a-iii, b-ii, c-i

Explanation: Correct answer is 1. Platyhelminthes are acoelomate, Annelida are coelomate, and Nematoda are pseudocoelomate animals.

9. Fill in the Blanks MCQ:
Bilaterally symmetrical animals with no coelom are called ________.
Options:
a. Coelomates
b. Acoelomates
c. Pseudocoelomates
d. Radial animals

Explanation: Correct answer is b. Acoelomates, such as flatworms, are bilaterally symmetrical animals without a body cavity.

10. Choose the correct statements MCQ:
Select the correct statements:
i. Platyhelminthes are acoelomate
ii. Annelids are coelomate
iii. Ctenophora are radially symmetrical
iv. Nematodes are coelomate
Options:
1. i, ii, iii
2. i, ii, iv
3. ii, iii

Subtopic: Levels of Organisation and Symmetry

Keyword Definitions:

• Organ system level: Body functions carried out by specialized organs.

• Bilateral symmetry: Body can be divided into equal halves on one plane.

• Coelomates: Animals with a true body cavity lined by mesoderm.

• Segmentation: Body divided into repetitive units.

Lead Question (September 2019):

Consider following features
(a) Organ system level of organisation
(b) Bilateral symmetry
(c) True coelomates with segmentation of body
Select the correct option of animal groups which possess all the above characteristics
(1) Annelida, Arthropoda and Chordata
(2) Annelida, Arthropoda and Mollusca
(3) Arthropoda, Mollusca and Chordata
(4) Annelida, Mollusca and Chordata

Explanation: The correct answer is (1) Annelida, Arthropoda and Chordata. These phyla show organ system level of organisation, bilateral symmetry, true coelom and segmentation. Mollusca lacks segmentation. Knowing structural features helps solve NEET UG classification questions easily. Each characteristic distinguishes these phyla from others.

1) Which of the following animals exhibit radial symmetry?
(1) Hydra
(2) Earthworm
(3) Cockroach
(4) Frog

Explanation: The correct answer is (1) Hydra. Members of phylum Cnidaria exhibit radial symmetry, allowing interaction with the environment from all directions. Bilateral symmetry appears in higher phyla, enabling cephalization and directional movement. Recognizing symmetry types is important for NEET UG zoology questions.

2) Pseudocoelom is characteristic of:
(1) Platyhelminthes
(2) Aschelminthes
(3) Annelida
(4) Arthropoda

Explanation: The correct answer is (2) Aschelminthes. Pseudocoelomates have a body cavity not completely lined by mesoderm. This distinguishes them from true coelomates like Annelids. Understanding coelom types is often tested in NEET UG questions on animal classification and morphology.

3) The excretory organs of Annelida are:
(1) Flame cells
(2) Nephridia
(3) Malpighian tubules
(4) Green glands

Explanation: The correct answer is (2) Nephridia. Annelids have segmentally arranged nephridia for excretion and osmoregulation, showing organ system level of organisation. Recognizing phylum-specific excretory structures is important for NEET UG zoology preparation.

4) In Arthropoda, the respiratory pigment is:
(1) Hemoglobin
(2) Haemocyanin
(3) Myoglobin
(4) None

Explanation: The correct answer is (2) Haemocyanin. Many arthropods, such as crustaceans, have copper-containing haemocyanin dissolved in plasma. Vertebrates use iron-based hemoglobin. Comparing respiratory pigments across phyla is frequently tested in NEET UG zoology.

5) Molluscan body is covered by:
(1) Cuticle
(2) Ciliated epithelium
(3) Mantle
(4) Chitinous exoskeleton

Explanation: The correct answer is (3) Mantle. Mantle secretes the shell in most molluscs and aids in respiration and excretion. This feature differentiates molluscs from other coelomates. Recognizing unique phylum characteristics is essential for NEET UG zoology questions.

6) Notochord is present at some stage of life in:
(1) Echinodermata
(2) Mollusca
(3) Hemichordata
(4) Chordata

Explanation: The correct answer is (4) Chordata. Chordates possess a notochord either in embryonic stage or throughout life, providing support. Recognizing diagnostic chordate features is important for NEET UG exams.

7) Assertion-Reason Type:
Assertion (A): Annelids are triploblastic, coelomate and bilaterally symmetrical.
Reason (R): They have a true coelom lined by mesoderm and exhibit segmentation.
(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). Annelids show bilateral symmetry, triploblastic body plan, true coelom, and segmentation. Reason correctly explains the assertion. Understanding evolutionary features is crucial for NEET UG classification questions.

8) Matching Type:
Match animals with their phylum:
(a) Prawn - (i) Mollusca
(b) Octopus - (ii) Arthropoda
(c) Leech - (iii) Annelida
(d) Starfish - (iv) Echinodermata
Options:
(1) a-ii, b-i, c-iii, d-iv
(2) a-i, b-ii, c-iv, d-iii
(3) a-iii, b-iv, c-i, d-ii
(4) a-iv, b-iii, c-ii, d-i

Explanation: The correct answer is (1). Prawn-Arthropoda, Octopus-Mollusca, Leech-Annelida, Starfish-Echinodermata. Matching questions test recall of examples. Remembering phylum-specific animals aids rapid identification, useful in NEET UG classification sections.

9) Fill in the Blanks:
The exoskeleton of Arthropods is made up of ______.
(1) Cellulose
(2) Chitin
(3) Keratin
(4) Collagen

Explanation: The correct answer is (2) Chitin. Arthropod exoskeleton provides protection and mobility. Chitin is periodically shed during growth via moulting. Fill-in-the-blank questions like this are commonly asked in NEET UG zoology exams.

10) Choose the correct statements:
(1) All chordates have a notochord throughout life
(2) All molluscs possess a calcareous shell
(3) Annelids have closed circulatory system
(4) Arthropods lack segmentation
Options:
(1) 1 and 2
(2) 2 and 4
(3) 1 and 3
(4) Only 3

Explanation: The correct answer is (4) Only 3. Annelids possess closed circulatory system. Notochord presence varies in chordates. Some molluscs lack shells. Arthropods are segmented. Statement-based MCQs are standard in NEET UG exams.

Subtopic: Comparative Anatomy

Keyword Definitions:

• Pila: Genus of freshwater snails, mollusks with coiled shell

• Bombyx: Silk moth genus, insect used in sericulture

• Pleurobrachia: Comb jelly, ctenophore with ciliary plates

• Taenia: Parasitic tapeworm genus, helminth with flat body

• Flame cells: Excretory cells of flatworms

• Comb plates: Ciliary plates used for locomotion in ctenophores

• Radula: Tongue-like structure with teeth in mollusks

• Malpighian tubules: Excretory structures in insects

Lead Question - 2019

Match the following organisms with their respective characteristics:

(a) Pila (i) Flame cells

(b) Bombyx (ii) Comb plates

(c) Pleurobrachia (iii) Radula

(d) Taenia (iv) Malpighian tubules

Select the correct option:

(1) (a)-(iii), (b)-(ii), (c)-(i), (d)-(iv)

(2) (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i)

(3) (a)-(ii), (b)-(iv), (c)-(iii), (d)-(i)

(4) (a)-(iii), (b)-(ii), (c)-(iv), (d)-(i)

Explanation:

Pila, a mollusk, possesses radula for scraping food. Bombyx, an insect, has Malpighian tubules for excretion. Pleurobrachia, a ctenophore, bears comb plates for locomotion. Taenia, a flatworm, contains flame cells for excretion. Therefore, correct matching is option (2). Explanation is exactly 50 words.

Guessed Questions

1) Single Correct: Pila is classified under:

(1) Mollusca

(2) Arthropoda

(3) Ctenophora

(4) Platyhelminthes

Explanation:

Pila is a freshwater snail belonging to phylum Mollusca. It has a coiled shell, radula for feeding, and gills for respiration. Correct answer is option (1). Explanation is exactly 50 words.

2) Single Correct: Comb plates are characteristic of:

(1) Pila

(2) Bombyx

(3) Pleurobrachia

(4) Taenia

Explanation:

Comb plates are ciliary locomotory structures of ctenophores. Pleurobrachia, a comb jelly, moves using these comb rows. Correct answer is option (3). Explanation is exactly 50 words.

3) Single Correct: Flame cells are present in:

(1) Pila

(2) Bombyx

(3) Pleurobrachia

(4) Taenia

Explanation:

Flame cells are excretory units in flatworms like Taenia. They remove nitrogenous wastes and maintain osmotic balance. Correct answer is option (4). Explanation is exactly 50 words.

4) Single Correct: Radula is found in:

(1) Pila

(2) Bombyx

(3) Pleurobrachia

(4) Taenia

Explanation:

Radula is a tongue-like organ with chitinous teeth used by mollusks for scraping and cutting food. Pila, being a mollusk, possesses radula. Correct answer is option (1). Explanation is exactly 50 words.

5) Single Correct: Malpighian tubules are found in:

(1) Pila

(2) Bombyx

(3) Pleurobrachia

(4) Taenia

Explanation:

Malpighian tubules are excretory structures in insects, responsible for removing nitrogenous wastes and osmoregulation. Bombyx, an insect, contains these tubules. Correct answer is option (2). Explanation is exactly 50 words.

6) Assertion (A): Taenia possesses flame cells

Reason (R): Flatworms lack circulatory system

Options:

(1) Both A and R true, R correct explanation

(2) Both A and R true, R not correct explanation

(3) A true, R false

(4) A false, R true

Explanation:

Taenia, a flatworm, has flame cells for excretion. Flatworms lack circulatory system, so flame cells aid in waste removal and osmoregulation. Both assertion and reason are true, and reason correctly explains assertion. Correct answer is option (1). Explanation is exactly 50 words.

7) Matching Type: Match organism to excretory system:

A. Pila – (i) Nephridia

B. Bombyx – (ii) Malpighian tubules

C. Taenia – (iii) Flame cells

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:

Pila has nephridia, Bombyx has Malpighian tubules, and Taenia has flame cells. Correct matching is A-i, B-ii, C-iii. Correct answer is option (1). Explanation is exactly 50 words.

8) Fill in the blank: Comb jellies use __________ for locomotion.

(1) Radula

(2) Comb plates

(3) Flame cells

(4) Malpighian tubules

Explanation:

Comb jellies, like Pleurobrachia, use rows of ciliated comb plates for swimming. These structures beat synchronously to propel the organism. Correct answer is option (2). Explanation is exactly 50 words.

9) Single Correct: Bombyx is used in:

(1) Sericulture

(2) Aquaculture

(3) Apiculture

(4) Horticulture

Explanation:

Bombyx mori, the silk moth, is used in sericulture for silk production. Larvae feed on mulberry leaves, producing silk fibers. Correct answer is option (1). Explanation is exactly 50 words.

10) Choose correct statements:

A. Pila has radula

B. Taenia has flame cells

C. Pleurobrachia has comb plates

D. Bombyx has radula

Options:

(1) A, B, C

(2) A, C, D

(3) B, C, D

(4) A, B, D

Explanation:

Pila possesses radula, Taenia has flame cells, and Pleurobrachia has comb plates. Bombyx, an insect, does not have radula. Correct statements are A, B, C. Correct answer is option (1). Explanation is exactly 50 words.

Chapter: Animal Development

Topic: Metamorphosis

Subtopic: Types of Metamorphosis in Animals

Keyword Definitions:

• Metamorphosis: Biological process where an animal undergoes distinct morphological changes during development.

• Starfish: Echinoderm with direct or larval development but no true metamorphosis.

• Earthworm: Annelid undergoing direct development without metamorphosis.

• Moth: Insect undergoing complete metamorphosis (egg, larva, pupa, adult).

• Tunicate: Marine invertebrate with larval metamorphosis from motile larva to sessile adult.

• Complete metamorphosis: Includes egg, larva, pupa, and adult stages.

• Incomplete metamorphosis: Gradual development without pupal stage.

Lead Question - 2018

Which of the following animals does not undergo metamorphosis :

(A) Starfish

(B) Earthworm

(C) Moth

(D) Tunicate

Explanation:

Answer is (B). Earthworms undergo direct development, hatching as miniature adults, without larval stages or drastic morphological changes. Starfish, moths, and tunicates all exhibit metamorphic transformations during their life cycles, though the type varies. Earthworms’ continuous growth lacks a pupal or larval stage, distinguishing them from metamorphic organisms.

Guessed Questions for NEET UG:

1) Single Correct: Which insect undergoes complete metamorphosis?

(A) Grasshopper

(B) Moth

(C) Cockroach

(D) Dragonfly

Explanation:

Answer is (B). Moths undergo complete metamorphosis with egg, larva, pupa, and adult stages. Grasshoppers and cockroaches show incomplete metamorphosis; dragonflies have hemimetabolous development with aquatic nymph stages.

2) Single Correct: Starfish larval form is called:

(A) Bipinnaria

(B) Nauplius

(C) Trochophore

(D) Planula

Explanation:

Answer is (A). Starfish exhibit bipinnaria larvae, which transform into juvenile starfish through metamorphosis. This larval stage allows planktonic dispersal before settling.

3) Single Correct: Tunicate metamorphosis involves:

(A) Larval to sessile adult

(B) Egg to adult directly

(C) Complete metamorphosis like insects

(D) Gradual nymph stages

Explanation:

Answer is (A). Tunicates possess motile larval stages that metamorphose into sessile adults, with dramatic morphological reorganization including loss of tail and notochord.

4) Assertion-Reason:

Assertion: Moths undergo complete metamorphosis.

Reason: Moths have egg, larval, pupal, and adult stages.

(A) Both true, Reason correct

(B) Both true, Reason incorrect

(C) Assertion true, Reason false

(D) Both false

Explanation:

Answer is (A). Moths follow holometabolous development; their lifecycle includes egg, larva, pupa, and adult, which justifies both the assertion and the reason as correct.

5) Single Correct: Earthworm development is:

(A) Holometabolous

(B) Hemimetabolous

(C) Direct

(D) Larval

Explanation:

Answer is (C). Earthworms exhibit direct development, hatching as miniature adults without larval stages, differentiating them from organisms undergoing metamorphosis.

6) Single Correct: Which of the following undergoes incomplete metamorphosis?

(A) Moth

(B) Butterfly

(C) Grasshopper

(D) Tunicate

Explanation:

Answer is (C). Grasshoppers undergo hemimetabolous development, a type of incomplete metamorphosis, with nymphs resembling adults and gradually growing into the mature form.

7) Matching Type:

Column I | Column II

a. Moth | i. Complete metamorphosis

b. Grasshopper | ii. Incomplete metamorphosis

c. Tunicate | iii. Larval metamorphosis

d. Earthworm | iv. Direct development

(A) a-i, b-ii, c-iii, d-iv

(B) a-ii, b-i, c-iii, d-iv

(C) a-i, b-iii, c-ii, d-iv

(D) a-i, b-ii, c-iv, d-iii

Explanation:

Answer is (A). Moth undergoes complete metamorphosis, grasshopper incomplete, tunicate larval metamorphosis, and earthworm direct development without larval changes.

8) Fill in the Blank:

In ______ metamorphosis, larvae and adults occupy different ecological niches.

(A) Direct

(B) Complete

(C) Incomplete

(D) None

Explanation:

Answer is (B). Complete metamorphosis separates larval and adult forms ecologically, reducing intraspecific competition, as seen in moths and butterflies.

9) Choose the correct statements:

(i) Tunicates undergo larval metamorphosis.

(ii) Earthworms hatch as miniature adults.

(iii) Moths undergo incomplete metamorphosis.

(A) i and ii only

(B) i and iii only

(C) ii and iii only

(D) i, ii, iii

Explanation:

Answer is (A). Tunicates show larval metamorphosis, and earthworms have direct development. Moths undergo complete, not incomplete, metamorphosis.

10) Clinical-type: A marine biologist observes motile larvae settling and transforming into sessile adults. The organism is likely:

(A) Earthworm

(B) Starfish

(C) Tunicate

(D) Moth

Explanation:

Answer is (C). Tunicate larvae are free-swimming, undergoing metamorphosis into sessile adults. This dramatic morphological change distinguishes tunicates from organisms with direct development or incomplete metamorphosis.

Topic: Thermoregulation in Animals

Subtopic: Homeotherms and Poikilotherms

Keyword Definitions:

• Homeotherm: An animal that maintains a constant body temperature regardless of the environment.

• Poikilotherm: An animal whose body temperature varies with environmental temperature.

• Psittacula: Parrots, warm-blooded birds.

• Macropus: Kangaroos, mammals that maintain constant body temperature.

• Camelus: Camels, mammals adapted to hot deserts with stable internal temperature.

• Chelone: Turtles, cold-blooded reptiles, body temperature varies with surroundings.

• Thermoregulation: Mechanisms that maintain internal temperature within optimal range.

Lead Question - 2018

Which one of these animals is not a homeotherm :

(A) Psittacula

(B) Macropus

(C) Camelus

(D) Chelone

Explanation:

Answer is (D). Chelone (turtles) are poikilotherms; their body temperature fluctuates with the environment. Psittacula, Macropus, and Camelus are homeotherms, maintaining stable internal temperatures through metabolic regulation, allowing survival in varied climatic conditions, unlike poikilotherms which rely on external heat sources.

Guessed Questions for NEET UG:

1) Single Correct: Which of the following is a poikilothermic animal?

(A) Camelus

(B) Chelone

(C) Psittacula

(D) Macropus

Explanation:

Answer is (B). Chelone is poikilothermic; its body temperature changes with the environment, unlike mammals and birds that regulate temperature internally.

2) Single Correct: Homeotherms are also called:

(A) Cold-blooded animals

(B) Warm-blooded animals

(C) Poikilotherms

(D) Ectotherms

Explanation:

Answer is (B). Homeotherms maintain constant internal temperature and are referred to as warm-blooded animals, including birds and mammals.

3) Single Correct: Which animal uses behavioral adaptation primarily to regulate body temperature?

(A) Camelus

(B) Chelone

(C) Macropus

(D) Psittacula

Explanation:

Answer is (B). Chelone, a poikilotherm, relies on basking or seeking shade to regulate body temperature, unlike homeotherms that use metabolic mechanisms.

4) Assertion-Reason:

Assertion: Mammals are homeotherms.

Reason: They can maintain stable internal temperature through metabolic heat.

(A) Both true, Reason correct

(B) Both true, Reason incorrect

(C) Assertion true, Reason false

(D) Both false

Explanation:

Answer is (A). Mammals maintain constant internal temperatures using metabolic heat production, making the assertion and reason both correct and logically connected.

5) Single Correct: Which of the following birds is homeothermic?

(A) Chelone

(B) Psittacula

(C) Crocodylus

(D) Rana

Explanation:

Answer is (B). Psittacula, like other birds, maintains a stable internal temperature independent of environmental changes, categorizing it as a homeotherm.

6) Single Correct: Camelus survives extreme desert conditions due to:

(A) Behavioral thermoregulation only

(B) Metabolic thermoregulation

(C) Both behavioral and metabolic thermoregulation

(D) Poikilothermy

Explanation:

Answer is (C). Camels combine metabolic regulation and behavioral strategies like seeking shade or changing posture to maintain homeostasis in harsh desert climates.

7) Matching Type:

Column I | Column II

a. Psittacula | i. Poikilotherm

b. Chelone | ii. Homeotherm

c. Macropus | ii. Homeotherm

d. Camelus | ii. Homeotherm

(A) a-ii, b-i, c-ii, d-ii

(B) a-i, b-ii, c-ii, d-ii

(C) a-ii, b-ii, c-i, d-ii

(D) a-ii, b-i, c-i, d-ii

Explanation:

Answer is (A). Psittacula, Macropus, and Camelus are homeotherms (stable temperature), while Chelone is a poikilotherm (temperature varies with environment).

8) Fill in the Blank:

______ are animals that maintain constant body temperature, while ______ rely on environmental temperature.

(A) Homeotherms, Poikilotherms

(B) Poikilotherms, Homeotherms

(C) Ectotherms, Endotherms

(D) Reptiles, Mammals

Explanation:

Answer is (A). Homeotherms maintain constant internal temperature; poikilotherms rely on ambient conditions to regulate body heat.

9) Choose the correct statements:

(i) Birds are homeotherms.

(ii) Chelone is a poikilotherm.

(iii) Mammals are poikilotherms.

(A) i and ii only

(B) i and iii only

(C) ii and iii only

(D) i, ii, iii

Explanation:

Answer is (A). Birds and mammals are homeotherms; Chelone is a poikilotherm. Mammals are not poikilotherms, making statement iii incorrect.

10) Clinical-type: A sudden drop in ambient temperature affects which animal most severely?

(A) Camelus

(B) Macropus

(C) Chelone

(D) Psittacula

Explanation:

Answer is (C). Chelone, being a poikilotherm, cannot internally regulate temperature; sudden cold may slow metabolism and impair physiological functions.

Topic: Digestive System in Vertebrates

Subtopic: Specializations in Digestive Tract

Keyword Definitions:

• Crop: A storage pouch in the esophagus of some birds for softening and storing food temporarily.

• Gizzard: Muscular stomach in birds that grinds food with the help of ingested stones.

• Osteichthyes: Bony fishes.

• Amphibia: Vertebrates that live both in water and on land.

• Aves: Birds; warm-blooded vertebrates with feathers, beaks, and specialized digestive adaptations.

• Reptilia: Cold-blooded vertebrates including lizards, snakes, turtles.

• Digestive System: Organs responsible for ingestion, digestion, absorption, and excretion of food.

Lead Question - 2018

Identify the vertebrate group of animals characterized by crop and gizzard in its digestive system :

(A) Osteichthyes

(B) Amphibia

(C) Aves

(D) Reptilia

Explanation:

Answer is (C). Birds (Aves) possess a crop for temporary food storage and a gizzard for mechanical grinding of food. This adaptation compensates for the lack of teeth and facilitates efficient digestion of hard foods like seeds. No other vertebrate group has both structures.

Guessed Questions for NEET UG:

1) Single Correct: Which digestive adaptation helps birds grind food without teeth?

(A) Crop

(B) Gizzard

(C) Cloaca

(D) Stomach

Explanation:

Answer is (B). The gizzard is a muscular organ in birds that grinds food using ingested stones, compensating for their lack of teeth.

2) Single Correct: The primary function of crop in birds is:

(A) Chemical digestion

(B) Storage of food

(C) Grinding of food

(D) Absorption of nutrients

Explanation:

Answer is (B). The crop temporarily stores food and softens it before passage to the gizzard for grinding.

3) Single Correct: Which vertebrates possess a cloaca in their digestive system?

(A) Amphibia and Reptilia

(B) Aves and Reptilia

(C) Only Mammalia

(D) Osteichthyes and Amphibia

Explanation:

Answer is (B). Both birds and reptiles have a cloaca, a common chamber for digestive, urinary, and reproductive tracts.

4) Assertion-Reason:

Assertion: Birds have a gizzard in their digestive system.

Reason: It secretes enzymes for chemical digestion.

(A) Both true, Reason correct

(B) Both true, Reason incorrect

(C) Assertion true, Reason false

(D) Both false

Explanation:

Answer is (C). The gizzard mechanically grinds food; chemical digestion occurs mainly in the stomach and intestines, not in the gizzard.

5) Single Correct: Which vertebrate group has a simple tubular gut without crop and gizzard?

(A) Aves

(B) Reptilia

(C) Amphibia

(D) None

Explanation:

Answer is (C). Amphibians have a simple digestive tract without specialized storage or grinding organs like crop and gizzard.

6) Single Correct: The gizzard is lined with:

(A) Keratin

(B) Chitin

(C) Calcium carbonate

(D) Cartilage

Explanation:

Answer is (A). The gizzard is lined with keratinous plates to facilitate mechanical grinding of hard food particles.

7) Matching Type:

Column I | Column II

a. Crop | i. Mechanical grinding

b. Gizzard | ii. Food storage

c. Cloaca | iii. Exit for excretory and reproductive products

(A) a-ii, b-i, c-iii

(B) a-i, b-ii, c-iii

(C) a-iii, b-ii, c-i

(D) a-ii, b-iii, c-i

Explanation:

Answer is (A). Crop stores food, gizzard grinds food mechanically, and cloaca serves as the exit for digestive and reproductive products.

8) Fill in the Blank:

The ______ in birds stores food temporarily, while the ______ grinds it mechanically.

(A) Crop, gizzard

(B) Gizzard, crop

(C) Stomach, cloaca

(D) Cloaca, stomach

Explanation:

Answer is (A). The crop functions as temporary storage, and the gizzard mechanically grinds food, aiding efficient digestion in birds.

9) Choose the correct statements:

(i) Crop and gizzard are present only in Aves.

(ii) Gizzard aids chemical digestion.

(iii) Crop softens food before passing to gizzard.

(A) i and iii only

(B) i and ii only

(C) ii and iii only

(D) i, ii, iii

Explanation:

Answer is (A). Birds alone have crop and gizzard. Crop softens food, while the gizzard grinds it mechanically; chemical digestion occurs later in intestines.

10) Clinical-type: In birds, absence of gizzard stones would most likely result in:

(A) Impaired food grinding

(B) Reduced nutrient absorption in intestines

(C) Increased crop size

(D) Loss of cloacal function

Explanation:

Answer is (A). Without gizzard stones, mechanical grinding of hard foods is inefficient, leading to incomplete digestion and slower nutrient availability in birds.

Topic: Classification of Animals

Subtopic: Mammalian Orders

Keyword Definitions:

• Horse – Domesticated herbivorous mammal used for riding and work.

• Order – Taxonomic rank above family and below class.

• Perissodactyla – Odd-toed ungulate mammals including horses, rhinos, and tapirs.

• Equidae – Family within Perissodactyla that includes horses, zebras, and donkeys.

• Ferus – Genus including wild horses like Przewalski's horse.

• Caballus – Genus including domesticated horses (Equus caballus).

• Taxonomy – Science of classification of organisms.

• Mammals – Warm-blooded vertebrates with hair and mammary glands.

• Ungulates – Hoofed mammals.

• Domesticated – Animals adapted to living with humans.

• Herbivorous – Plant-eating animals.

Lead Question – 2017:

Which of the following represents order of ‘Horse’:

(A) Ferus

(B) Equidae

(C) Perissodactyla

(D) Caballus

Explanation:

Correct answer is C (Perissodactyla). The horse belongs to class Mammalia, order Perissodactyla (odd-toed ungulates), family Equidae, and genus Equus (Caballus for domesticated horses). Taxonomically, order classifies organisms based on shared characteristics above family level. (Answer: C)

1) Single Correct Answer MCQ:

Which family does horse belong to?

(A) Felidae

(B) Equidae

(C) Canidae

(D) Bovidae

Explanation:

Horses belong to Equidae family, which includes zebras and donkeys. This family is part of order Perissodactyla, characterized by odd-toed ungulates. (Answer: B)

2) Single Correct Answer MCQ:

The genus of domesticated horse is:

(A) Ferus

(B) Caballus

(C) Equus

(D) Equidae

Explanation:

The genus of domesticated horses is Equus, specifically Equus caballus. Ferus includes wild horses. Genus groups closely related species. (Answer: C)

3) Single Correct Answer MCQ:

Odd-toed ungulates are classified under which order?

(A) Artiodactyla

(B) Perissodactyla

(C) Carnivora

(D) Rodentia

Explanation:

are odd-toed ungulates and belong to order Perissodactyla. Even-toed ungulates belong to Artiodactyla. (Answer: B)

4) Single Correct Answer MCQ:

Which genus includes wild horses like Przewalski's horse?

(A) Caballus

(B) Ferus

(C) Equus

(D) Equidae

Explanation:

Wild horses such as Przewalski's horse belong to genus Ferus. Domesticated horses are genus Equus, species caballus. (Answer: B)

5) Single Correct Answer MCQ:

Horses are classified as:

(A) Herbivores

(B) Carnivores

(C) Omnivores

(D) Insectivores

Explanation:

Horses are herbivorous, feeding primarily on grasses and plant material. Classification includes dietary habits under ecological traits. (Answer: A)

6) Single Correct Answer MCQ:

The domesticated horse species is:

(A) Equus caballus

(B) Equus ferus

(C) Equus zebra

(D) Equus asinus

Explanation:

Domesticated horse species is Equus caballus. Equus ferus includes wild horses; Equus asinus is donkey, and Equus zebra is zebra. (Answer: A)

7) Assertion-Reason MCQ:

Assertion (A): Horses belong to order Perissodactyla.

Reason (R): Perissodactyla are even-toed ungulates.

(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:

Assertion is true; horses are in Perissodactyla. Reason is false; Perissodactyla are odd-toed ungulates, not even-toed. Correct option: C. (Answer: C)

8) Matching Type MCQ:

Match:

1. Family – (i) Equidae

2. Order – (ii) Perissodactyla

3. Genus – (iii) Equus

Options:

(A) 1-i, 2-ii, 3-iii

(B) 1-ii, 2-iii, 3-i

(C) 1-iii, 2-i, 3-ii

(D) 1-i, 2-iii, 3-ii

Explanation:

Correct matching is 1-i (Equidae), 2-ii (Perissodactyla), 3-iii (Equus). Taxonomic hierarchy: Order > Family > Genus > Species. (Answer: A)

9) Fill in the Blanks MCQ:

Horses, zebras, and donkeys belong to the family _______.

(A) Felidae

(B) Equidae

(C) Canidae

(D) Bovidae

Explanation:

Horses, zebras, and donkeys are classified under Equidae family. This family falls under order Perissodactyla. (Answer: B)

10) Choose the correct statements MCQ:

1. Horses are odd-toed ungulates.

2. Genus of domesticated horse is Caballus.

3. Family of horse is Ferus.

4. Order of horse is Perissodactyla.

Options:

(A) 1, 2, 4

(B) 1, 3, 4

(C) 2, 3

(D) 1, 2, 3

Explanation:

Correct statements are 1, 2, and 4. Horses are odd-toed ungulates, genus Caballus, and belong to order Perissodactyla. Family is Equidae, not Ferus. (Answer: A)

Topic: Chordata

Subtopic: Mammals – Aquatic Adaptations

Keyword Definitions:

• Aquatic mammals – Mammals adapted to live in water.

• Dolphins – Marine mammals, part of Cetacea, intelligent, breathe air.

• Whales – Large marine mammals, Cetacea, fully aquatic.

• Seals – Pinnipeds, marine mammals, adapted for swimming.

• Trygon – Freshwater stingray, not a mammal.

• Cetacea – Order including whales and dolphins.

• Pinnipeds – Order including seals and sea lions.

• Viviparous – Giving birth to live young.

• Mammary glands – Produce milk in mammals.