Animal Kingdom

Topic: Phylum Echinodermata; Subtopic: Water Vascular System and Its Functions

Keyword Definitions:

• Echinoderms: Marine invertebrates with a calcareous endoskeleton and radial symmetry in adults, e.g., starfish and sea urchins.

• Water vascular system: A network of fluid-filled canals unique to echinoderms, responsible for locomotion, food capture, and respiration.

• Tube feet: Extensions of the water vascular system used for movement, attachment, and sensory functions.

• Madreporite: A sieve-like structure through which seawater enters the water vascular system.

• Radial canal: A canal extending from the ring canal along each arm in starfish for distributing fluid to tube feet.

Lead Question - 2025

Role of the water vascular system in Echinoderms is:
A. Respiration and Locomotion
B. Excretion and Locomotion
C. Capture and transport of food
D. Digestion and Respiration
E. Digestion and Excretion
Choose the correct answer from the options given below:
(1) A and B Only
(2) A and C only
(3) B and C Only
(4) B, D and E only

Explanation: The water vascular system in echinoderms is a unique hydraulic system aiding in locomotion, food capture, and respiration. Seawater enters through the madreporite, travels via canals, and controls tube feet movements through fluid pressure. It plays no direct role in digestion or excretion. Answer: (2) A and C only

1. Which of the following structures allows water to enter the water vascular system in starfish?
(1) Radial canal
(2) Madreporite
(3) Stone canal
(4) Tube feet
Explanation: The madreporite is a porous, plate-like structure located on the aboral surface of starfish, allowing seawater to enter the water vascular system. It connects to the stone canal, which leads to the ring canal surrounding the mouth. Answer: (2) Madreporite

2. In echinoderms, the tube feet are primarily involved in:
(1) Excretion
(2) Respiration and locomotion
(3) Reproduction
(4) Secretion
Explanation: Tube feet, part of the water vascular system, are used for locomotion, food capture, and gaseous exchange. Their suction power and fluid pressure help echinoderms move and cling to surfaces underwater efficiently. Answer: (2) Respiration and locomotion

3. Which of the following is NOT a function of the water vascular system?
(1) Respiration
(2) Circulation
(3) Reproduction
(4) Locomotion
Explanation: The water vascular system performs multiple roles like movement, respiration, and food handling but does not take part in reproduction. Echinoderm reproduction is sexual and occurs through separate gonads in arms. Answer: (3) Reproduction

4. The radial canal in echinoderms is connected to:
(1) Stone canal
(2) Ampullae
(3) Ring canal
(4) Tube feet
Explanation: The radial canal extends from the ring canal into each arm and connects to ampullae and tube feet. It distributes water pressure to aid movement and control extension or retraction of tube feet. Answer: (3) Ring canal

5. The water vascular system is a characteristic feature of:
(1) Mollusca
(2) Echinodermata
(3) Arthropoda
(4) Annelida
Explanation: The water vascular system is unique to echinoderms such as starfish and sea urchins. It functions as a hydraulic system for locomotion, feeding, and respiration, absent in other phyla. Answer: (2) Echinodermata

6. Which of the following correctly represents the sequence of structures through which water flows in the water vascular system?
(1) Madreporite → Ring canal → Stone canal → Tube feet
(2) Madreporite → Stone canal → Ring canal → Radial canal → Tube feet
(3) Stone canal → Madreporite → Tube feet → Radial canal
(4) Madreporite → Radial canal → Stone canal → Tube feet
Explanation: Water enters through the madreporite, flows into the stone canal, then to the ring canal, followed by radial canals, ampullae, and finally to tube feet. This sequence allows efficient regulation of movement and pressure. Answer: (2) Madreporite → Stone canal → Ring canal → Radial canal → Tube feet

7. Assertion-Reason Type:
Assertion (A): Water vascular system helps in respiration.
Reason (R): Water vascular system supplies oxygenated blood throughout the body.
(1) Both A and R are true, and R is the correct explanation of A
(2) Both A and R are true, but R is not the correct explanation of A
(3) A is true, but R is false
(4) Both A and R are false
Explanation: The water vascular system helps in gaseous exchange through tube feet and body surface but does not transport oxygenated blood, as echinoderms lack a circulatory system. Hence, A is true but R is false. Answer: (3) A is true, but R is false

8. Matching Type:
Match the following structures with their functions:
A. Madreporite — I. Entry of water
B. Stone canal — II. Connects madreporite to ring canal
C. Tube feet — III. Movement and respiration
D. Ring canal — IV. Central circular canal
(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-II, C-I, D-III
Explanation: Madreporite allows water entry, stone canal connects to the ring canal, tube feet assist in movement and respiration, and ring canal serves as the central hub. Hence, A-I, B-II, C-III, D-IV is correct. Answer: (1) A-I, B-II, C-III, D-IV

9. Fill in the Blanks:
The water vascular system of echinoderms opens to the exterior through the ________.
(1) Mouth
(2) Tube feet
(3) Madreporite
(4) Radial canal
Explanation: The madreporite serves as the external opening of the water vascular system, allowing seawater entry. It acts as a pressure regulator and filters out particles, ensuring smooth hydraulic movement in echinoderms. Answer: (3) Madreporite

10. Choose the Correct Statements:
Statement I: The water vascular system helps in locomotion, respiration, and food capture.
Statement II: It helps in digestion and reproduction.
(1) Both statements are correct
(2) Only Statement I is correct
(3) Only Statement II is correct
(4) Both statements are incorrect
Explanation: The water vascular system performs locomotion, respiration, and food transport but not digestion or reproduction. It operates through a series of canals controlling tube feet pressure hydraulically. Hence, only Statement I is correct. Answer: (2) Only Statement I is correct

Topic: Chordates and Non-Chordates; Subtopic: Subphylum Vertebrata and its Characteristics

Keyword Definitions:
• Chordates: Animals possessing a notochord, dorsal hollow nerve cord, and pharyngeal gill slits at some stage of life.
• Vertebrates: Chordates in which the notochord is replaced by a vertebral column during development.
• Notochord: A flexible rod-like structure that provides skeletal support in embryos of all chordates.
• Pharyngeal slits: Openings in the pharynx used for filter feeding or respiration, characteristic of chordates.

Lead Question – 2025

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): The members of subphylum vertebrata possess notochord during the embryonic period; the notochord is replaced by a cartilaginous or bony vertebral column in adults.

In the light of the above statements, choose the correct answer from the options given below:
(1) Both A and R are true and R is the correct explanation of A
(2) Both A and R are true but R is not the correct explanation of A
(3) A is true but R is false
(4) A is false but R is true

Explanation:
The correct answer is (1) Both A and R are true and R is the correct explanation of A. All vertebrates possess notochord in the embryonic stage which later becomes the vertebral column, a defining feature of subphylum Vertebrata. However, not all chordates have a vertebral column; some retain the notochord throughout life, such as Amphioxus. Thus, R correctly explains A.

Guessed Questions:

1. Which of the following characters is common to all chordates?
(1) Paired appendages
(2) Notochord
(3) Scales
(4) Exoskeleton
Explanation: All chordates possess a notochord at some stage of their life, along with a dorsal hollow nerve cord and pharyngeal gill slits. These are the fundamental features distinguishing chordates from non-chordates. Hence, the correct answer is (2) Notochord.

2. The subphylum Vertebrata differs from other chordates in having:
(1) Dorsal tubular nerve cord
(2) Pharyngeal gill slits
(3) Vertebral column
(4) Post-anal tail
Explanation: Vertebrates are chordates in which the notochord is replaced by a cartilaginous or bony vertebral column during development, providing structural support and protection to the spinal cord. Hence, the correct answer is (3) Vertebral column.

3. Which of the following animals is a chordate but not a vertebrate?
(1) Amphioxus
(2) Frog
(3) Pigeon
(4) Dog
Explanation: Amphioxus (Branchiostoma) is a cephalochordate, possessing a notochord throughout life but lacking a vertebral column. It shows the basic chordate features without being a vertebrate. Hence, the correct answer is (1) Amphioxus.

4. Which structure in chordates develops into the spinal cord in vertebrates?
(1) Pharyngeal slit
(2) Notochord
(3) Dorsal hollow nerve cord
(4) Post-anal tail
Explanation: The dorsal hollow nerve cord, a key feature of chordates, develops into the brain and spinal cord in vertebrates, forming the central nervous system. Hence, the correct answer is (3) Dorsal hollow nerve cord.

5. In vertebrates, the notochord is replaced by which structure during development?
(1) Spinal cord
(2) Vertebral column
(3) Neural tube
(4) Pharyngeal slits
Explanation: The notochord is replaced by the vertebral column during the embryonic development of vertebrates. This column forms the main axial support and protects the spinal cord. Hence, the correct answer is (2) Vertebral column.

6. Which of the following features is absent in non-chordates?
(1) Open circulatory system
(2) Notochord
(3) Segmentation
(4) Bilateral symmetry
Explanation: Non-chordates lack a notochord, which is the defining characteristic of chordates. Many non-chordates possess bilateral symmetry and segmentation, but not a notochord. Hence, the correct answer is (2) Notochord.

Matching Type:
Match List I with List II:
List-I          List-II
A. Protochordata        I. Amphioxus
B. Vertebrata        II. Fishes
C. Urochordata        III. Ascidia
D. Cephalochordata     IV. Balanoglossus

(1) A-IV, B-II, C-III, D-I
(2) A-II, B-III, C-IV, D-I
(3) A-I, B-II, C-IV, D-III
(4) A-III, B-IV, C-I, D-II
Explanation: The correct answer is (1) A-IV, B-II, C-III, D-I. Protochordata includes Hemichordates like Balanoglossus, Vertebrata includes Fishes, Urochordata includes Ascidia, and Cephalochordata includes Amphioxus. These examples illustrate the evolutionary diversity among chordates.

Fill in the Blanks:
The notochord in vertebrates is replaced by a _______.
(1) Spinal cord
(2) Vertebral column
(3) Cartilage
(4) Nerve cord
Explanation: During vertebrate development, the embryonic notochord is replaced by a vertebral column composed of cartilage or bone, forming the backbone. This provides protection and structural support. Hence, the correct answer is (2) Vertebral column.

Choose the Correct Statements:
Statement I: All chordates have a notochord throughout life.
Statement II: Vertebrates replace notochord with a vertebral column.
(1) Both statements are true
(2) Both statements are false
(3) Only Statement I is true
(4) Only Statement II is true
Explanation: The correct answer is (4). In most chordates, the notochord is present at some stage of life, but not always throughout. Vertebrates specifically replace it with a vertebral column, while cephalochordates like Amphioxus retain it permanently.

10. Assertion-Reason Type:
Assertion (A): Urochordates and Cephalochordates are non-vertebrate chordates.
Reason (R): They possess a notochord but lack a vertebral column.
(1) Both A and R are true and R is the correct explanation of A
(2) Both A and R are true but R is not the correct explanation of A
(3) A is true but R is false
(4) A is false but R is true
Explanation: The correct answer is (1). Urochordates and Cephalochordates belong to non-vertebrate chordates because they show chordate features such as notochord, dorsal nerve cord, and pharyngeal slits but do not possess a vertebral column. Their structure represents primitive chordate organization before evolution of vertebrates.

Topic: Phylum Chordata; Subtopic: Cyclostomata

Keyword Definitions:

• Cyclostomata: Jawless, eel-like aquatic vertebrates including lampreys and hagfishes.

• Endoparasite: An organism that lives inside the host’s body and derives nourishment.

• Ectoparasite: Parasite living on the surface of the host.

• Symbiotic: A close, long-term biological interaction between two organisms.

• Free-living: Organisms that are not parasitic and can survive independently.

Lead Question – 2025

All living members of the class Cyclostomata are:
(1) Free living
(2) Endoparasite
(3) Symbiotic
(4) Ectoparasite

Explanation: All living members of Cyclostomata, such as lampreys and hagfishes, are ectoparasitic or scavengers on fishes. They possess circular, suctorial mouths without jaws but with keratinized teeth for attaching to hosts. Their parasitic lifestyle aids feeding on host’s blood and tissues. Hence, the correct answer is (4) Ectoparasite.

Guessed Questions

1. The heart of Cyclostomes is:
(1) Two-chambered
(2) Three-chambered
(3) Four-chambered
(4) Single-chambered
Explanation: Cyclostomes have a two-chambered heart consisting of one atrium and one ventricle. It pumps blood in a single circuit, characteristic of lower vertebrates like fishes. Their circulation is closed, and oxygenation occurs through gills. Hence, the correct answer is (1) Two-chambered.

2. The excretory organ in Cyclostomata is:
(1) Nephridia
(2) Kidneys
(3) Malpighian tubules
(4) Flame cells
Explanation: Cyclostomes possess paired mesonephric kidneys for excretion and osmoregulation. These organs filter nitrogenous wastes and maintain ion balance in their aquatic environment. Hence, the correct answer is (2) Kidneys.

3. Cyclostomes lack which of the following structures?
(1) Jaws and paired fins
(2) Brain
(3) Spinal cord
(4) Notochord
Explanation: Cyclostomes are jawless vertebrates without paired fins. They retain the notochord throughout life, and have brain and spinal cord. The absence of jaws and paired fins distinguishes them from Gnathostomes. Hence, the correct answer is (1) Jaws and paired fins.

4. Example of a Cyclostome is:
(1) Petromyzon
(2) Scoliodon
(3) Torpedo
(4) Trygon
Explanation: Petromyzon, commonly called the lamprey, is a jawless, eel-shaped ectoparasitic fish. It belongs to class Cyclostomata and attaches to other fishes using a suctorial mouth. Hence, the correct answer is (1) Petromyzon.

5. Cyclostomes are exclusively:
(1) Marine
(2) Freshwater
(3) Amphibious
(4) Terrestrial
Explanation: Cyclostomes are exclusively marine but migrate to freshwater for spawning. After reproduction, adults die, and larvae return to the sea after metamorphosis. Hence, the correct answer is (1) Marine.

6. The mouth of Cyclostomes is:
(1) Circular and jawless
(2) Terminal and toothed
(3) Ventral and jawed
(4) Dorsal and paired
Explanation: Cyclostomes possess a circular, jawless, suctorial mouth used for attachment to hosts. It contains keratinized teeth adapted for feeding on host tissues and blood. Hence, the correct answer is (1) Circular and jawless.

7. Assertion–Reason Type:
Assertion (A): Cyclostomes are primitive vertebrates.
Reason (R): They possess a cartilaginous skeleton and lack paired appendages.
(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: Cyclostomes are primitive vertebrates due to their cartilaginous endoskeleton, absence of jaws, and paired fins. The reason correctly explains the assertion. Hence, the correct answer is (1) Both A and R are true and R explains A.

8. Matching Type:
List I – Organisms
A. Petromyzon
B. Myxine
C. Scoliodon
D. Trygon
List II – Class
I. Cyclostomata
II. Cyclostomata
III. Chondrichthyes
IV. Chondrichthyes
(1) A–I, B–II, C–III, D–IV
(2) A–III, B–I, C–IV, D–II
(3) A–II, B–I, C–III, D–IV
(4) A–I, B–III, C–II, D–IV
Explanation: Petromyzon (lamprey) and Myxine (hagfish) belong to class Cyclostomata, while Scoliodon and Trygon are cartilaginous fishes under Chondrichthyes. Hence, the correct answer is (1) A–I, B–II, C–III, D–IV.

9. Fill in the Blanks:
Cyclostomes respire through ______.
(1) Gills
(2) Lungs
(3) Tracheae
(4) Skin
Explanation: Cyclostomes respire through gills. They possess 6–15 pairs of gill pouches with external openings. These gills facilitate aquatic respiration by oxygenating blood and removing CO₂. Hence, the correct answer is (1) Gills.

10. Choose the Correct Statements:
Statement I: Cyclostomes are jawless vertebrates with circular mouths.
Statement II: They have paired appendages for locomotion.
(1) Both statements are correct
(2) Both statements are incorrect
(3) Statement I correct, Statement II incorrect
(4) Statement I incorrect, Statement II correct
Explanation: Cyclostomes are jawless vertebrates with circular mouths adapted for sucking. However, they lack paired fins or appendages. Hence, the correct answer is (3) Statement I correct, Statement II incorrect.

Topic: Body Cavity and Germ Layers; Subtopic: Types of Coelom

Keyword Definitions:

• Coelom: A fluid-filled cavity between body wall and gut, lined by mesoderm.

• Mesoderm: The middle germ layer in triploblastic animals, forming muscles and connective tissues.

• Acoelomate: Animals without a body cavity between body wall and gut wall.

• Schizocoelomate: Animals having a true coelom formed by the splitting of mesodermal masses.

• Pseudocoelomate: Animals with a false coelom not fully lined by mesoderm.

Lead Question - 2025

While trying to find out the characteristic of a newly found animal, a researcher did the histology of the adult animal and observed a cavity with the presence of mesodermal tissue towards the alimentary canal. What could be the possible coelome of that animal?

(1) Acoelomate

(2) Pseudocoelomate

(3) Schizocoelomate

(4) Spongocoelomate

Explanation:

A schizocoelomate animal has a true coelom formed by the splitting of mesodermal cells. The mesodermal layer lines both the body wall and organs around the alimentary canal. This structure provides better organ protection and flexibility. Examples include annelids, molluscs, and arthropods. Hence, the correct answer is (3) Schizocoelomate.

Guessed Questions:

1. Which of the following animals is an acoelomate?

(1) Earthworm

(2) Ascaris

(3) Planaria

(4) Cockroach

Explanation:

Planaria, a flatworm, lacks a body cavity between its gut and body wall, making it an acoelomate. Its organs are embedded in a solid parenchyma. Earthworm and cockroach are coelomates, while Ascaris is pseudocoelomate. Thus, the correct answer is (3) Planaria.

2. Which of the following organisms is pseudocoelomate?

(1) Nereis

(2) Ascaris

(3) Hydra

(4) Pheretima

Explanation:

Ascaris, a nematode, has a pseudocoelom where the body cavity is not entirely lined by mesoderm. The mesoderm is present only on the outer body wall. This cavity acts as a hydrostatic skeleton. Hence, the correct answer is (2) Ascaris.

3. Which of the following correctly matches the type of coelom with its example?

(1) Acoelomate – Annelida

(2) Pseudocoelomate – Arthropoda

(3) Schizocoelomate – Mollusca

(4) Haemocoelomate – Platyhelminthes

Explanation:

Mollusca, Annelida, and Arthropoda are schizocoelomates, where the coelom develops by splitting of mesodermal masses. Hence, the correct match is (3) Schizocoelomate – Mollusca. Haemocoelomates like arthropods have reduced coeloms and open circulatory systems.

4. In which group of animals is the body cavity derived from the blastocoel of the embryo?

(1) Acoelomates

(2) Pseudocoelomates

(3) Schizocoelomates

(4) Coelomates

Explanation:

In pseudocoelomates, the coelomic cavity arises from the embryonic blastocoel rather than mesodermal splitting. This cavity is only partially lined with mesoderm. Hence, the correct answer is (2) Pseudocoelomates.

5. Which coelomic condition allows for independent movement of body organs?

(1) Acoelomate

(2) Pseudocoelomate

(3) Coelomate

(4) None of these

Explanation:

Coelomates possess a true coelomic cavity completely lined with mesoderm, allowing body organs to move independently of the body wall. This improves physiological efficiency and movement flexibility. Hence, the correct answer is (3) Coelomate.

6. The body cavity of arthropods is called:

(1) Haemocoel

(2) Schizocoel

(3) Blastocoel

(4) Pseudocoel

Explanation:

Arthropods have a haemocoel, a reduced coelomic space filled with blood or haemolymph. It acts as part of the open circulatory system, where blood directly bathes organs. Hence, the correct answer is (1) Haemocoel.

Assertion-Reason Question

7. Assertion (A): Coelomates possess better organ organization than pseudocoelomates.

Reason (R): True coelom allows organ development independent of body wall movement.

(1) Both A and R are true and R is the correct explanation of A

(2) Both A and R are true but R is not the correct explanation of A

(3) A is true but R is false

(4) A is false but R is true

Explanation:

Coelomates have a true coelom lined with mesoderm, allowing organs to grow and move independently. This enhances body function coordination. Both assertion and reason are true, and R correctly explains A. Correct answer: (1) Both A and R are true and R is the correct explanation of A.

Matching Type Question

8. Match the following:

A. Acoelomate – 1. Platyhelminthes

B. Pseudocoelomate – 2. Ascaris

C. Coelomate – 3. Earthworm

D. Haemocoelomate – 4. Cockroach

(1) A-1, B-2, C-3, D-4

(2) A-2, B-1, C-4, D-3

(3) A-3, B-1, C-2, D-4

(4) A-4, B-3, C-1, D-2

Explanation:

Platyhelminthes are acoelomate, Ascaris is pseudocoelomate, earthworm is coelomate, and cockroach has haemocoel. Hence, the correct match is (1) A-1, B-2, C-3, D-4.

Fill in the Blanks Question

9. The coelom of annelids is formed by the splitting of ______ tissue.

(1) Ectodermal

(2) Endodermal

(3) Mesodermal

(4) Peritoneal

Explanation:

In annelids, the coelom is formed through schizocoely, where the mesodermal cells split to form the cavity. This true coelom provides space for internal organ development. Hence, the correct answer is (3) Mesodermal.

Choose the Correct Statements (Statement I & II)

10. Statement I: Pseudocoelomates possess a body cavity completely lined by mesoderm.

Statement II: Coelomates have a true coelom formed by mesodermal splitting.

(1) Both Statement I and II are correct

(2) Both Statement I and II are incorrect

(3) Statement I is incorrect but Statement II is correct

(4) Statement I is correct but Statement II is incorrect

Explanation:

Pseudocoelomates have a cavity not fully lined by mesoderm, while coelomates form a true coelom by mesodermal splitting. Therefore, Statement I is incorrect, and Statement II is correct. Correct answer: (3) Statement I is incorrect but Statement II is correct.

Topic: Coelom and Body Cavity; Subtopic: Classification Based on Presence of Coelom

Keyword Definitions:

• Coelom: The true body cavity formed between body wall and gut wall, lined by mesoderm.

• Mesoderm: The middle germ layer in triploblastic animals forming muscles, connective tissues, and organs.

• Hemichordates: Marine deuterostomes showing a true coelom and pharyngeal gill slits.

• Aschelminthes: Pseudocoelomate animals having a body cavity not lined by mesoderm.

• Pseudocoelom: A false body cavity not fully lined by mesodermal epithelium.

Lead Question - 2024 (Jhajjhar)
Assertion (A): In hemichordates the body cavity is lined by mesoderm.
Reason (R): In aschelminthes the body cavity is not lined by mesoderm.

In the light of the above statements, choose the correct answer from the options given below:
1. Both (A) and (R) are True and (R) is the correct explanation of (A).
2. Both (A) and (R) are True but (R) is not the correct explanation of (A).
3. (A) is True but (R) is False.
4. (A) is False but (R) is True.

Explanation: The correct answer is option 2. Hemichordates possess a true coelom lined by mesoderm, while Aschelminthes have a pseudocoel not lined by mesoderm. Both statements are true but describe different phyla, hence (R) is not the correct explanation for (A). Coelom evolution marks increasing body complexity and organ development in animals.

Guessed Questions:

1. Animals without a true coelom are called:
1. Acoelomates
2. Pseudocoelomates
3. Coelomates
4. Diploblastic
Explanation: The correct answer is option 1. Acoelomates lack a body cavity between the body wall and gut wall. They are triploblastic but without coelom, such as Platyhelminthes. This structural feature restricts organ development and flexibility in body movement.

2. The body cavity of Aschelminthes is derived from:
1. Blastocoel
2. Coelomic pouches
3. Archenteron
4. Mesenchyme
Explanation: The correct answer is option 1. Aschelminthes are pseudocoelomates whose body cavity originates from the embryonic blastocoel. This cavity is not lined by mesodermal peritoneum and helps distribute nutrients and waste within the organism.

3. Which of the following animals is acoelomate?
1. Earthworm
2. Roundworm
3. Tapeworm
4. Cockroach
Explanation: The correct answer is option 3. Tapeworms belong to Platyhelminthes, which are acoelomates. They lack a true body cavity, and their internal organs are embedded in solid mesenchymal tissue, limiting internal organ specialization.

4. Coelom is completely lined by mesodermal epithelium in:
1. Coelomates
2. Acoelomates
3. Pseudocoelomates
4. Diploblastic animals
Explanation: The correct answer is option 1. True coelomates, such as annelids, molluscs, and chordates, have a body cavity entirely lined by mesoderm. This arrangement allows efficient organ placement, movement, and protection in higher animals.

5. Which group of animals shows pseudocoelomate condition?
1. Annelida
2. Aschelminthes
3. Arthropoda
4. Mollusca
Explanation: The correct answer is option 2. Aschelminthes, including roundworms, have a pseudocoelom derived from the blastocoel. It serves as a hydrostatic skeleton aiding locomotion and distribution of nutrients in the body.

6. Which of the following statements is correct?
1. Coelomates have no body cavity.
2. Pseudocoelomates have coelom lined on both sides by mesoderm.
3. Acoelomates lack coelom.
4. All triploblastic animals are coelomates.
Explanation: The correct answer is option 3. Acoelomates such as flatworms lack a coelom entirely. Their body cavity is filled with parenchyma, which supports internal organs and limits free movement within the body.

7. Assertion-Reason Type:
Assertion (A): In Aschelminthes, pseudocoel is present.
Reason (R): Pseudocoel is lined by both ectoderm and endoderm.
1. Both (A) and (R) are true and (R) is correct explanation of (A).
2. Both (A) and (R) are true but (R) is not correct explanation of (A).
3. (A) is true but (R) is false.
4. (A) is false but (R) is true.
Explanation: The correct answer is option 3. Aschelminthes do possess a pseudocoel, but it is not lined by both ectoderm and endoderm. It remains unlined by mesoderm and hence is not a true coelom.

8. Matching Type:
Match the animal with its body cavity type:
A. Platyhelminthes — (i) True coelom
B. Nematoda — (ii) Acoelomate
C. Annelida — (iii) Pseudocoelomate

1. A-(ii), B-(iii), C-(i)
2. A-(iii), B-(i), C-(ii)
3. A-(i), B-(ii), C-(iii)
4. A-(ii), B-(i), C-(iii)
Explanation: The correct answer is option 1. Platyhelminthes are acoelomate, Nematoda pseudocoelomate, and Annelida coelomate. This classification reflects evolutionary advancement from simple to complex body cavities among animals.

9. Fill in the Blanks:
The body cavity in roundworms is called ________.
1. Blastocoel
2. Coelom
3. Pseudocoel
4. Archenteron
Explanation: The correct answer is option 3. Roundworms have a pseudocoel derived from the blastocoel. It functions as a hydrostatic skeleton and aids in nutrient circulation throughout the organism’s body.

10. Choose the Correct Statements:
Statement I: Coelomates have organs suspended in fluid-filled body cavity.
Statement II: Pseudocoelomates lack mesoderm lining the body cavity.
1. Both statements are correct.
2. Both statements are incorrect.
3. Only Statement I is correct.
4. Only Statement II is correct.
Explanation: The correct answer is option 1. Coelomates possess a fluid-filled coelom lined by mesoderm, allowing proper organ development. Pseudocoelomates, on the other hand, have a cavity not lined by mesoderm, making both statements accurate.

Topic: Phylum Echinodermata; Subtopic: Examples and Common Names of Echinoderms

Keyword Definitions:

• Echinodermata: A phylum of marine animals with radial symmetry, calcareous endoskeleton, and water vascular system.

• Water vascular system: A network of fluid-filled canals in echinoderms used for locomotion and food capture.

• Tube feet: Small extensions used for movement and attachment in echinoderms.

• Radial symmetry: Body arrangement around a central axis, typical of adult echinoderms.

• Endoskeleton: Internal skeleton made of calcareous ossicles providing structure and protection.

Lead Question - 2024 (Jhajjhar)

Match List-I with List-II:

List-I (Biological Name)  List-II (Common name)

A. Asterias  I. Sea urchin

B. Antedon  II. Brittle star

C. Echinus  III. Sea lily

D. Ophiura  IV. Star fish

1. A-III, B-IV, C-II, D-I

2. A-IV, B-III, C-I, D-II

3. A-II, B-III, C-I, D-IV

4. A-I, B-II, C-IV, D-III

Explanation:

Echinoderms are exclusively marine organisms exhibiting pentamerous radial symmetry. Asterias is commonly known as Starfish, Antedon as Sea lily, Echinus as Sea urchin, and Ophiura as Brittle star. They possess a unique water vascular system and show regeneration ability. Hence, the correct match is A-IV, B-III, C-I, D-II. Their diversity represents various adaptations to marine life.

1. Which feature is characteristic of all echinoderms?

1. Bilateral symmetry

2. Chitinous exoskeleton

3. Water vascular system

4. Segmented body

Explanation:

All echinoderms possess a water vascular system—a network of canals involved in locomotion, feeding, and respiration. This system operates hydraulic tube feet enabling slow movement and food handling. Unlike arthropods, they lack segmentation and chitinous exoskeleton. Hence, the defining feature is the water vascular system.

2. The larval form of echinoderms exhibits:

1. Radial symmetry

2. Bilateral symmetry

3. Asymmetry

4. Spherical symmetry

Explanation:

Echinoderm larvae, such as bipinnaria and pluteus, show bilateral symmetry unlike adults that exhibit radial symmetry. This indicates their evolutionary link to bilaterally symmetrical ancestors. During metamorphosis, larval symmetry changes to radial symmetry. Hence, the correct answer is bilateral symmetry.

3. Which among the following is a characteristic feature of echinoderm digestive system?

1. Incomplete

2. Complete with mouth and anus

3. Absent

4. Found only in larvae

Explanation:

Most echinoderms possess a complete digestive system having both mouth and anus, though in some (like brittle stars), the anus is reduced. They are carnivorous or detritivorous and digest food extracellularly. Hence, the correct answer is complete digestive system with mouth and anus.

4. Which one of the following belongs to class Asteroidea?

1. Asterias

2. Ophiura

3. Antedon

4. Echinus

Explanation:

The class Asteroidea includes starfishes like Asterias, characterized by pentamerous arms radiating from a central disc. They exhibit regeneration and tube feet for movement. Thus, the correct answer is Asterias.

5. In echinoderms, the coelom is:

1. Absent

2. Pseudocoelom

3. True coelom

4. Blood-filled cavity

Explanation:

Echinoderms are coelomates possessing a true coelom derived from mesoderm. The coelomic fluid aids in circulation and distribution of nutrients. This distinguishes them from pseudocoelomates. Hence, the correct answer is true coelom.

6. The function of tube feet in starfish is:

1. Excretion

2. Respiration

3. Locomotion and food capture

4. Circulation

Explanation:

Tube feet in echinoderms are small extensions operated by the water vascular system used for locomotion and food capture. They also help in respiration and attachment to surfaces. Hence, the correct answer is locomotion and food capture.

Assertion-Reason Type Question

7. Assertion (A): Echinoderms show radial symmetry in adults.

Reason (R): They are sedentary and adapted to free-swimming life.

1. Both (A) and (R) are correct and (R) explains (A).

2. Both (A) and (R) are correct but (R) does not explain (A).

3. (A) is correct but (R) is incorrect.

4. (A) is incorrect but (R) is correct.

Explanation:

Adult echinoderms exhibit radial symmetry suited for a slow-moving or sedentary benthic life, not free-swimming activity. Hence, the assertion is correct, but the reason is incorrect.

Matching Type Question

8. Match the following classes with their examples:

A. Asteroidea — I. Brittle star

B. Ophiuroidea — II. Sea lily

C. Echinoidea — III. Sea urchin

D. Crinoidea — IV. Starfish

1. A-IV, B-I, C-III, D-II

2. A-II, B-III, C-I, D-IV

3. A-I, B-IV, C-II, D-III

4. A-III, B-II, C-IV, D-I

Explanation:

Starfish belong to class Asteroidea, brittle star to Ophiuroidea, sea urchin to Echinoidea, and sea lily to Crinoidea. Hence, the correct match is A-IV, B-I, C-III, D-II.

Fill in the Blanks Type Question

9. The exoskeleton of echinoderms is made up of ________.

1. Chitin

2. Silica

3. Calcareous ossicles

4. Keratin

Explanation:

Echinoderms possess an endoskeleton made of calcareous ossicles derived from mesodermal tissue. These ossicles form spiny plates giving the phylum its name (“spiny-skinned”). Hence, the correct answer is calcareous ossicles.

Choose the Correct Statements (Statement I & II)

10. Statement I: Echinoderms are exclusively marine.

Statement II: They possess a water vascular system.

1. Both statements are correct.

2. Both statements are incorrect.

3. Statement I is correct, but Statement II is incorrect.

4. Statement I is incorrect, but Statement II is correct.

Explanation:

Both statements are correct. Echinoderms are exclusively marine and show a unique water vascular system for locomotion and feeding. They cannot survive in freshwater or terrestrial habitats due to osmotic limitations. 

Topic: Non-Chordates; Subtopic: General Characteristics of Non-Chordates

Keyword Definitions:
• Notochord: A flexible rod-like structure found in chordates that supports the body.
• Gill slits: Openings in the pharynx used for respiration and filter-feeding in aquatic animals.
• Dorsal/Ventral: Dorsal refers to the back side, while ventral refers to the belly side of an organism.
• Post-anal tail: An extension of the body beyond the anus found in chordates.
• Non-chordates: Animals lacking a notochord, dorsal nerve cord, and post-anal tail at any stage of life.

Lead Question - 2024
The following are the statements about non-chordates:
A. Pharynx is perforated by gill slits.
B. Notochord is absent
C. Central nervous system is dorsal
D. Heart is dorsal if present
E. Post anal tail is absent
Choose the most appropriate answer from the options given below:
(1) A, B & D only
(2) B, D & E only
(3) B, C & D only
(4) A & C only

Explanation:
The correct answer is (2) B, D & E only. Non-chordates are characterized by the absence of a notochord, a ventral (not dorsal) heart if present, and a central nervous system that is solid and ventral. They also lack a post-anal tail. Gill slits and dorsal nerve cords are features of chordates, not non-chordates. (100 words)

1. Which of the following features distinguishes chordates from non-chordates?
(1) Bilateral symmetry
(2) Coelomic body cavity
(3) Presence of notochord
(4) Segmented body
Explanation: The correct answer is (3) Presence of notochord. The presence of a notochord is the most distinguishing feature of chordates. Non-chordates lack this structure, while chordates possess it at least in some stage of life, supporting the body axis and aiding movement. (100 words)

2. In non-chordates, the central nervous system is:
(1) Dorsal and hollow
(2) Dorsal and solid
(3) Ventral and solid
(4) Ventral and hollow
Explanation: The correct answer is (3) Ventral and solid. Non-chordates possess a solid ventral nerve cord, in contrast to chordates which have a hollow dorsal nerve cord. This key difference marks a fundamental distinction in their nervous system organization. (100 words)

3. Which of the following statements is true for chordates but false for non-chordates?
(1) Presence of coelom
(2) Presence of pharyngeal gill slits
(3) Absence of segmentation
(4) Presence of closed circulatory system
Explanation: The correct answer is (2) Presence of pharyngeal gill slits. Gill slits are characteristic of chordates, either in the embryonic or adult stage. Non-chordates lack these, showing a fundamental evolutionary difference in respiratory structures. (100 words)

4. Assertion-Reason Question:
Assertion (A): Non-chordates lack a post-anal tail.
Reason (R): They possess a dorsal nerve cord like chordates.
(1) Both A and R are true, and R is the correct explanation of A
(2) Both A and R are true, but R is not the correct explanation of A
(3) A is true, but R is false
(4) A is false, but R is true
Explanation: The correct answer is (3) A is true, but R is false. Non-chordates indeed lack a post-anal tail, but their nerve cord is ventral, not dorsal. This difference defines the body organization contrast between chordates and non-chordates. (100 words)

5. Match the following:
List I (Feature) | List II (Organism Type)
A. Dorsal nerve cord | I. Non-chordate
B. Notochord present | II. Chordate
C. Post-anal tail absent | III. Non-chordate
D. Heart ventral | IV. Chordate
(1) A-II, B-I, C-III, D-IV
(2) A-II, B-II, C-I, D-I
(3) A-II, B-II, C-III, D-I
(4) A-I, B-II, C-II, D-I
Explanation: The correct answer is (3) A-II, B-II, C-III, D-I. Chordates show dorsal nerve cords and notochords, while non-chordates have ventral hearts and lack post-anal tails. These contrasting traits form the structural foundation of animal classification. (100 words)

6. Which of the following correctly represents non-chordate features?
(1) Dorsal nerve cord and post-anal tail
(2) Notochord and dorsal heart
(3) Ventral nerve cord and ventral heart
(4) Dorsal heart and dorsal nerve cord
Explanation: The correct answer is (3) Ventral nerve cord and ventral heart. Non-chordates display a ventral heart and a solid ventral nerve cord, opposite to chordates’ dorsal arrangement. This contrast helps in taxonomic differentiation between these two major animal groups. (100 words)

7. Fill in the blanks:
Non-chordates have a __________ nerve cord and a __________ heart.
(1) Dorsal, dorsal
(2) Ventral, ventral
(3) Dorsal, ventral
(4) Ventral, dorsal
Explanation: The correct answer is (2) Ventral, ventral. Non-chordates possess both ventral nerve cords and ventral hearts, while chordates have dorsal arrangements. This opposite organization is one of the most significant distinguishing features between the two. (100 words)

8. Which of the following characteristics is absent in all non-chordates?
(1) Segmentation
(2) Bilateral symmetry
(3) Post-anal tail
(4) Open circulatory system
Explanation: The correct answer is (3) Post-anal tail. The post-anal tail is a defining feature of chordates and is completely absent in non-chordates. It extends beyond the anus and aids in locomotion and balance in many chordate species. (100 words)

9. Which among the following is not a characteristic of chordates?
(1) Dorsal nerve cord
(2) Ventral heart
(3) Notochord
(4) Post-anal tail
Explanation: The correct answer is (2) Ventral heart. Chordates possess a dorsal heart, while non-chordates have a ventral one. This distinction forms one of the primary anatomical differences in the organization of body systems across animal phyla. (100 words)

10. Choose the correct statements:
Statement I: Non-chordates lack a notochord.
Statement II: Their central nervous system is ventral and solid.
(1) Both I and II are true
(2) Both I and II are false
(3) I is true but II is false
(4) I is false but II is true
Explanation: The correct answer is (1) Both I and II are true. Non-chordates completely lack a notochord and possess a ventral, solid nerve cord. These are primary features that distinguish them from chordates, helping to classify organisms into major animal groups. (100 words)

Topic: Non-Chordates and Chordates; Subtopic: Classification and Examples

Keyword Definitions:

• Pleurobrachia: A marine organism belonging to phylum Ctenophora, commonly known as sea walnut.

• Radula: A rasping feeding organ found in Molluscs used for scraping food.

• Stomochord: A rod-like structure in Hemichordates, supporting the proboscis.

• Air bladder: A gas-filled organ in bony fishes aiding buoyancy regulation.

Lead Question - 2024
Match List I with List II
List I                                          List II
A. Pleurobrachia                                I. Mollusca
B. Radula                                        II. Ctenophora
C. Stomochord                               III. Osteichthyes
D. Air bladder                                    IV. Hemichordata
Choose the correct answer from the options given below
(1) A-II, B-I, C-IV, D-III
(2) A-II, B-IV, C-I, D-III
(3) A-IV, B-III, C-II, D-I
(4) A-IV, B-II, C-III, D-I
Explanation: The correct match is (1) A-II, B-I, C-IV, D-III. Pleurobrachia belongs to Ctenophora, known for bioluminescence. Radula is a rasping structure of Molluscs used for feeding. Stomochord is present in Hemichordata, considered a primitive support. Air bladder aids buoyancy in Osteichthyes, preventing sinking. These features define evolutionary adaptations across phyla.

1. Which of the following organisms belongs to the phylum Hemichordata?
(1) Balanoglossus
(2) Aurelia
(3) Ascaris
(4) Sycon
Explanation: The correct answer is (1) Balanoglossus. It is a marine worm-like organism classified under Hemichordata. It has a proboscis, collar, and trunk, and exhibits a stomochord, a structure once thought to be similar to the notochord. It serves as a connecting link between non-chordates and chordates, exhibiting transitional features.

2. Radula is characteristic of which group of animals?
(1) Mollusca
(2) Echinodermata
(3) Cnidaria
(4) Annelida
Explanation: The correct answer is (1) Mollusca. The radula is a ribbon-like chitinous structure with tiny teeth used for scraping or cutting food before ingestion. It is absent in bivalves but common in gastropods and cephalopods. It is one of the diagnostic characters used to identify molluscs among invertebrates.

3. The air bladder in fishes helps in:
(1) Respiration
(2) Reproduction
(3) Maintaining buoyancy
(4) Locomotion
Explanation: The correct answer is (3) Maintaining buoyancy. The air bladder, also known as the swim bladder, regulates buoyancy by adjusting gas content, allowing fishes to remain at specific water depths. It is typically found in Osteichthyes but absent in cartilaginous fishes. It represents an evolutionary adaptation to aquatic life.

4. Pleurobrachia is commonly known as:
(1) Sea fan
(2) Sea walnut
(3) Sea pen
(4) Sea lily
Explanation: The correct answer is (2) Sea walnut. Pleurobrachia belongs to phylum Ctenophora. It is a transparent, gelatinous marine animal with eight comb plates used for locomotion. It exhibits bioluminescence and is hermaphroditic. Ctenophores show biradial symmetry and are important planktonic organisms found in marine ecosystems.

5. Stomochord is found in:
(1) Urochordata
(2) Hemichordata
(3) Cephalochordata
(4) Echinodermata
Explanation: The correct answer is (2) Hemichordata. Stomochord is a hollow, rod-like structure in the proboscis region of Balanoglossus and other hemichordates. It supports the anterior end and aids in food conduction. It differs structurally and functionally from the notochord found in true chordates. Hence, Hemichordata is a separate phylum.

6. Which of the following is not a characteristic feature of Ctenophores?
(1) Bioluminescence
(2) Biradial symmetry
(3) Polyp stage
(4) Ciliary comb plates
Explanation: The correct answer is (3) Polyp stage. Ctenophores exhibit only the medusa-like body form with biradial symmetry and locomotion through eight ciliary comb plates. They are exclusively marine, often bioluminescent, and lack the alternation of generations seen in cnidarians. Their unique colloblast cells capture prey instead of nematocysts.

7. Assertion (A): Stomochord resembles the notochord.
Reason (R): Both structures are homologous in origin and function.
(1) Both A and R are true, and R is the correct explanation of A.
(2) Both A and R are true, but R is not the correct explanation of A.
(3) A is true, but R is false.
(4) A is false, but R is true.
Explanation: The correct answer is (3). A is true, but R is false. Stomochord resembles a notochord only superficially but is not homologous. It arises from the endoderm, while the notochord originates from the mesoderm. Therefore, Hemichordates are not considered true chordates.

8. Match the following structures with their respective animal groups:
A. Colloblasts - I. Mollusca
B. Radula - II. Ctenophora
C. Tube feet - III. Echinodermata
D. Flame cells - IV. Platyhelminthes
(1) A-II, B-I, C-III, D-IV
(2) A-I, B-II, C-IV, D-III
(3) A-IV, B-I, C-II, D-III
(4) A-II, B-IV, C-III, D-I
Explanation: The correct answer is (1) A-II, B-I, C-III, D-IV. Colloblasts occur in Ctenophores for prey capture, Radula in Mollusca for feeding, Tube feet in Echinoderms for locomotion, and Flame cells in Platyhelminthes for excretion. These specialized structures help in identification and classification of organisms across phyla.

9. Fill in the blank:
In bony fishes, the ________ helps maintain buoyancy by adjusting gas volume.
(1) Air bladder
(2) Gills
(3) Lateral line
(4) Operculum
Explanation: The correct answer is (1) Air bladder. This organ controls buoyancy by regulating the gas content inside. It allows the fish to remain suspended at desired depths without expending energy. In some species, it also functions in sound production and hearing, reflecting adaptation to aquatic life.

10. Choose the correct statements:
Statement I: Stomochord and notochord are homologous structures.
Statement II: Radula is used for feeding in molluscs.
(1) Both statements are correct.
(2) Only Statement I is correct.
(3) Only Statement II is correct.
(4) Both statements are incorrect.
Explanation: The correct answer is (3) Only Statement II is correct. Stomochord is analogous, not homologous, to the notochord. Radula is indeed a feeding organ in molluscs used for scraping or cutting food. Hence, Statement II is true while Statement I is false, showing key evolutionary distinctions.

Topic: Chordates and Non-Chordates; Subtopic: Classification of Fishes and Their Common Names

Keyword Definitions:
• Pterophyllum: Commonly known as Angel fish, a freshwater ornamental teleost belonging to class Osteichthyes.
• Myxine: Known as Hag fish, a jawless marine vertebrate belonging to class Cyclostomata.
• Pristis: Also called Saw fish, a cartilaginous fish belonging to class Chondrichthyes.
• Exocoetus: Commonly called Flying fish, capable of gliding above water using wing-like pectoral fins.
• Teleosts: Bony fishes belonging to Osteichthyes, having endoskeleton made of bone and operculum covering the gills.

Lead Question – 2024

Match List I with List II
List I            List II
A. Pterophyllum        I. Hag fish
B. Myxine           II. Saw fish
C. Pristis           III. Angel fish
D. Exocoetus          IV. Flying fish

Choose the correct answer from the options given below
(1) A-III, B-I, C-II, D-IV
(2) A-IV, B-I, C-II, D-III
(3) A-III, B-II, C-I, D-IV
(4) A-II, B-I, C-III, D-IV

Explanation: The correct answer is (1) A–III, B–I, C–II, D–IV. Pterophyllum is the Angel fish, a freshwater bony fish. Myxine or Hag fish belongs to Cyclostomata, known for feeding on dead animals. Pristis or Saw fish belongs to Chondrichthyes, characterized by a saw-like rostrum. Exocoetus or Flying fish glides above water to escape predators using large pectoral fins.

Guessed Question 1: Which of the following is a cartilaginous fish?
(1) Labeo
(2) Pristis
(3) Exocoetus
(4) Pterophyllum

Explanation: Pristis, or Saw fish, is a cartilaginous fish belonging to class Chondrichthyes. Its skeleton is composed entirely of cartilage. The elongated snout bears tooth-like structures resembling a saw. It exhibits internal fertilization and lacks an operculum over gills, unlike bony fishes.

Guessed Question 2: Identify the correct match:
(1) Exocoetus – Angel fish
(2) Myxine – Hag fish
(3) Pterophyllum – Saw fish
(4) Pristis – Flying fish

Explanation: The correct match is Myxine – Hag fish. Myxine belongs to Cyclostomata, a group of primitive jawless vertebrates. These are marine scavengers with circular mouths and a cartilaginous skeleton. They secrete mucus for protection and can tie themselves in knots for leverage during feeding.

Guessed Question 3: Which of the following is a jawless vertebrate?
(1) Pristis
(2) Pterophyllum
(3) Myxine
(4) Exocoetus

Explanation: Myxine is a jawless vertebrate belonging to class Cyclostomata. These fishes lack jaws, paired fins, and scales. They possess cartilaginous skeletons and gill pouches for respiration. Their circular, suctorial mouths are used to feed on decaying fish and marine invertebrates.

Guessed Question 4: Which of the following pairs is incorrectly matched?
(1) Pterophyllum – Angel fish
(2) Pristis – Saw fish
(3) Exocoetus – Flying fish
(4) Myxine – Electric fish

Explanation: Option (4) is incorrect. Myxine is a Hag fish, not an electric fish. Electric fishes like Torpedo and Electrophorus produce electric shocks using specialized organs. Myxine, however, secretes slime for protection and belongs to Cyclostomata, a group of jawless vertebrates.

Guessed Question 5: The fish capable of gliding above the water surface is:
(1) Pristis
(2) Exocoetus
(3) Myxine
(4) Pterophyllum

Explanation: Exocoetus, or Flying fish, is capable of gliding above the water surface using its enlarged pectoral fins. It performs this action to escape from predators. It belongs to class Osteichthyes and has a streamlined body with an air bladder for buoyancy control.

Guessed Question 6: Which of the following is an ornamental freshwater fish?
(1) Exocoetus
(2) Pterophyllum
(3) Pristis
(4) Myxine

Explanation: Pterophyllum, commonly known as Angel fish, is an ornamental freshwater fish belonging to class Osteichthyes. It is popular in aquariums for its attractive color patterns and long dorsal and anal fins. It thrives in warm, slow-moving tropical waters and feeds on small insects and larvae.

Guessed Question 7 (Assertion–Reason Type):
Assertion (A): Exocoetus is called Flying fish.
Reason (R): It can glide above the water surface using enlarged fins.
(1) Both A and R are true, and R is the correct explanation of A
(2) Both A and R are true, but R is not the correct explanation of A
(3) A is true, but R is false
(4) A is false, but R is true

Explanation: Both A and R are true, and R correctly explains A. Exocoetus, the Flying fish, uses its large pectoral fins to glide for several meters above the water surface. This adaptation helps in evading aquatic predators and conserving energy during rapid movements.

Guessed Question 8 (Matching Type):
Match the following fish with their classification:
A. Pristis   I. Cyclostomata
B. Myxine  II. Chondrichthyes
C. Exocoetus III. Osteichthyes
Choose the correct answer:
(1) A-I, B-II, C-III
(2) A-II, B-I, C-III
(3) A-III, B-II, C-I
(4) A-II, B-III, C-I

Explanation: The correct answer is (2). Pristis belongs to Chondrichthyes, Myxine to Cyclostomata, and Exocoetus to Osteichthyes. These classes differ in skeletal structure, gill covering, and mode of fertilization. Chondrichthyes possess cartilaginous skeletons, while Osteichthyes have bony skeletons and opercula.

Guessed Question 9 (Fill in the Blanks):
_________ is commonly called Angel fish and belongs to class Osteichthyes.
(1) Pristis
(2) Exocoetus
(3) Pterophyllum
(4) Myxine

Explanation: Pterophyllum is the Angel fish, belonging to class Osteichthyes. It has a laterally compressed body and colorful scales, adapted to freshwater habitats. It is commonly bred for aquariums and shows parental care by guarding its eggs and fry against predators.

Guessed Question 10 (Choose the Correct Statements):
Statement I: Myxine belongs to Cyclostomata and lacks jaws.
Statement II: Pristis has a bony skeleton and external fertilization.
(1) Both statements are true
(2) Statement I is true, but Statement II is false
(3) Statement I is false, but Statement II is true
(4) Both statements are false

Explanation: The correct answer is (2). Myxine indeed belongs to Cyclostomata and lacks jaws. However, Pristis, or Saw fish, has a cartilaginous skeleton and undergoes internal fertilization. It is a bottom-dwelling marine predator with a saw-like snout used for hunting.

Topic: Body Organization and Coelom; Subtopic: Types of Body Cavities

Keyword Definitions:

• Coelom: True body cavity lined by mesoderm.

• Acoelomate: Animals without a body cavity between body wall and gut.

• Pseudocoelomate: Body cavity not fully lined by mesoderm.

• True Coelomate: Organisms having coelom completely lined with mesodermal epithelium.

• Animal Kingdom: Classification of multicellular heterotrophic organisms based on body organization.

Lead Question (2024)

Consider the following statements:
A. Annelids are true coelomates
B. Poriferans are pseudocoelomates
C. Aschelminthes are acoelomates
D. Platyhelminthes are pseudocoelomates
Choose the correct answer from the options given below:
(1) A only
(2) C only
(3) D only
(4) B only

Explanation: The correct answer is (1) A only. Annelids possess a true coelom lined by mesoderm, Poriferans lack body cavities, Platyhelminthes are acoelomates, and Aschelminthes possess pseudocoelom. Thus, only Annelids are true coelomates among these groups. The type of coelom helps classify animals based on evolutionary body organization.

1. Which of the following organisms are acoelomates?
(1) Ascaris
(2) Planaria
(3) Earthworm
(4) Nereis
Explanation: The correct answer is (2) Planaria. Platyhelminthes such as Planaria lack a true body cavity, making them acoelomates. The space between body wall and gut is filled with parenchyma. This structural simplicity marks a primitive organization in the evolution of animal body plans.

2. The body cavity of Ascaris is derived from:
(1) Mesoderm
(2) Endoderm
(3) Blastocoel
(4) Ectoderm
Explanation: The correct answer is (3) Blastocoel. In Ascaris (a pseudocoelomate), the cavity between body wall and gut arises from the blastocoel of the embryo. This cavity is not completely lined with mesoderm, thus making it a pseudocoelom, allowing movement of internal organs and fluid transport.

3. Which of the following animals possesses a true coelom?
(1) Hydra
(2) Ascaris
(3) Earthworm
(4) Planaria
Explanation: The correct answer is (3) Earthworm. Earthworms are annelids and have a true coelom completely lined by mesodermal tissue. This coelomic cavity acts as a hydrostatic skeleton and provides space for organ development, allowing efficient body movement and physiological function.

4. In which group of animals is the body cavity absent?
(1) Platyhelminthes
(2) Aschelminthes
(3) Annelida
(4) Mollusca
Explanation: The correct answer is (1) Platyhelminthes. They are acoelomates with no true body cavity; the space between the body wall and gut is filled with mesenchymal cells. Their flat body allows diffusion of nutrients and gases due to absence of circulatory and coelomic systems.

5. Assertion-Reason Type:
Assertion (A): Coelom provides space for development of complex organs.
Reason (R): Coelomates possess a cavity fully lined by mesoderm.
(1) Both A and R are true and R is the correct explanation of A.
(2) Both A and R are true but R is not the correct explanation of A.
(3) A is true but R is false.
(4) A is false but R is true.
Explanation: The correct answer is (1). Coelom formation allows organ development and suspension, while mesodermal lining provides cushioning and support. Thus, coelom enables complexity in organ systems seen in higher animals such as annelids and chordates.

6. Fill in the Blanks:
Animals having a body cavity not completely lined by mesoderm are called _________.
(1) Acoelomates
(2) Coelomates
(3) Pseudocoelomates
(4) Hemocoelates
Explanation: The correct answer is (3) Pseudocoelomates. Their body cavity arises from the embryonic blastocoel and lacks complete mesodermal lining. Examples include Ascaris and other roundworms, where this pseudocoelom serves as a hydrostatic skeleton aiding in body flexibility and movement.

7. Matching Type:
Match the following animal phyla with their type of coelom:
A. Platyhelminthes — (i) True coelom
B. Annelida — (ii) Acoelomate
C. Aschelminthes — (iii) Pseudocoelom
Choose the correct option:
(1) A-ii, B-i, C-iii
(2) A-iii, B-i, C-ii
(3) A-i, B-ii, C-iii
(4) A-ii, B-iii, C-i
Explanation: The correct answer is (1). Platyhelminthes are acoelomates, Annelids have true coelom, and Aschelminthes possess pseudocoelom. This reflects progressive evolution of body cavity providing space for organ specialization and physiological efficiency.

8. Choose the correct statements:
Statement I: Coelom allows independent movement of internal organs.
Statement II: In acoelomates, organs are embedded directly in solid mesoderm.
(1) Both statements are true.
(2) Only Statement I is true.
(3) Only Statement II is true.
(4) Both statements are false.
Explanation: The correct answer is (1). Coelom acts as a fluid-filled cavity permitting free organ movement, while acoelomates lack such cavity, resulting in restricted internal motion. These differences mark evolutionary advancement toward complex body organization.

9. Which of the following groups shows organ-system level of organization with coelom?
(1) Cnidaria
(2) Annelida
(3) Porifera
(4) Platyhelminthes
Explanation: The correct answer is (2) Annelida. Members like earthworm exhibit true coelom and organ-system level of organization. Their body is segmented with specialized organs for excretion, circulation, and locomotion, indicating a major evolutionary advancement from simpler phyla.

10. Which of the following animals is pseudocoelomate?
(1) Earthworm
(2) Tapeworm
(3) Ascaris
(4) Hydra
Explanation: The correct answer is (3) Ascaris. Roundworms such as Ascaris possess pseudocoelom formed from the blastocoel. It serves as a hydrostatic skeleton and assists internal transport. Unlike true coelom, the cavity lacks complete mesodermal lining, distinguishing pseudocoelomates from coelomates.

Topic: Invertebrates; Subtopic: Platyhelminthes, Ctenophores, Tapeworms, Sponges

Keyword Definitions:

• Platyhelminthes: Bilaterally symmetrical, triploblastic, acoelomate flatworms including planaria and tapeworms.

• Pseudocoelomate: Organism with a body cavity partially lined by mesoderm.

• Ctenophores: Marine invertebrates with comb rows, diploblastic structure, and bioluminescence.

• Fertilization: Fusion of male and female gametes, can be internal or external.

• Tapeworms: Parasitic flatworms with internal fertilization, hermaphroditic segments, no separate sexes.

• Sponges (Porifera): Simple, mostly marine, sessile animals with porous bodies, external fertilization, and direct development.

• Diploblastic: Animals with two germ layers: ectoderm and endoderm.

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

• Bilaterally Symmetrical: Body plan with mirror-image left and right halves.

• Bioluminescence: Production of light by living organisms, common in ctenophores.

• Development: Series of changes from fertilization to adult formation, can be direct or indirect.

Lead Question - 2023 (Manipur):

Select the correct statements:

A: Platyhelminthes are triploblastic, pseudocoelomate and bilaterally symmetrical organisms
B: Ctenophores reproduce only sexually and fertilization is external
C: In tapeworm, fertilization is internal but sexes are not separate
D: Ctenophores are exclusively marine, diploblastic and bioluminescent organisms
E: In sponges, fertilization is external and development is direct

Choose the correct answer from the options given below:

1. (A), (C) and (D) only
2. (B), (C) and (D) only
3. (A) and (E) only
4. (B) and (D) only

Explanation: Correct option is (B), (C) and (D) only. Platyhelminthes are triploblastic but acoelomate, not pseudocoelomate, and show bilateral symmetry. Tapeworms are hermaphroditic with internal fertilization. Ctenophores are exclusively marine, diploblastic, and bioluminescent. Sponges exhibit external fertilization and indirect development. Understanding these features is crucial for classification and evolutionary relationships. Structural characteristics, reproductive strategies, and developmental modes differentiate phyla. Correct knowledge aids in recognizing adaptations, ecological roles, and phylogenetic placement of invertebrates in the animal kingdom, forming a foundation for comparative zoology and functional biology.

Guessed MCQs:

1. Single Correct Answer MCQ: Platyhelminthes are:
(A) Diploblastic and acoelomate
(B) Triploblastic and acoelomate
(C) Triploblastic and pseudocoelomate
(D) Diploblastic and pseudocoelomate
Explanation: Triploblastic and acoelomate is correct. Platyhelminthes have three germ layers but lack a body cavity, classifying them as acoelomates. They show bilateral symmetry and cephalization. Understanding germ layer composition and coelom type helps in comparative anatomy and evolutionary biology. Acoelomate structure limits organ development but enables flat body for diffusion-based respiration and nutrient distribution, highlighting adaptations in parasitic and free-living flatworms.

2. Single Correct Answer MCQ: Ctenophores are:
(A) Freshwater, triploblastic, non-luminescent
(B) Marine, diploblastic, bioluminescent
(C) Marine, triploblastic, non-luminescent
(D) Terrestrial, diploblastic, bioluminescent
Explanation: Marine, diploblastic, bioluminescent is correct. Ctenophores possess two germ layers, lack a coelom, and produce light via bioluminescence. They are exclusively marine and use ciliary combs for locomotion. Their diploblastic structure represents primitive tissue organization, contrasting triploblastic in more advanced phyla. Bioluminescence aids predation and defense. Understanding these features helps differentiate Ctenophora from Cnidaria and provides insight into evolutionary biology of early metazoans.

3. Single Correct Answer MCQ: Fertilization in sponges is:
(A) Internal
(B) External
(C) Hermaphroditic
(D) Asexual
Explanation: External is correct. Sponges release sperm into water for external fertilization, and zygotes develop into free-swimming larvae. This facilitates dispersal. Sponges show indirect development and lack true tissues, making them primitive metazoans. Fertilization type helps classify animals and understand reproductive strategies. External fertilization suits sessile lifestyle, while larvae ensure colonization of new habitats, illustrating adaptation to environmental constraints and primitive body organization.

4. Single Correct Answer MCQ: Tapeworms are:
(A) Dioecious with external fertilization
(B) Hermaphroditic with internal fertilization
(C) Dioecious with internal fertilization
(D) Asexual only
Explanation: Hermaphroditic with internal fertilization is correct. Tapeworms possess both male and female reproductive organs in each segment, allowing self-fertilization or cross-fertilization. This ensures reproduction within host intestines. Understanding reproductive strategies is key for parasitology, epidemiology, and control measures. Hermaphroditism enables survival in host-dependent lifestyles, compensating for limited mobility and enhancing propagation in constrained environments.

5. Single Correct Answer MCQ: Ctenophores locomote using:
(A) Muscular foot
(B) Ciliary combs
(C) Flagella
(D) Pseudopodia
Explanation: Ciliary combs is correct. Ctenophores have comb rows with cilia, called ctenes, which beat synchronously to move through water. This primitive locomotion reflects diploblastic organization without muscles. Bioluminescence complements predation. Understanding locomotion aids taxonomy and functional biology of early metazoans. It exemplifies adaptation of simple body plan to marine environment, demonstrating coordination without advanced muscular or nervous systems.

6. Single Correct Answer MCQ: Development in sponges is:
(A) Direct
(B) Indirect
(C) Internal
(D) Viviparous
Explanation: Indirect is correct. Sponges produce free-swimming larvae which settle and develop into adults. Fertilization is external. Indirect development facilitates dispersal, colonization, and survival of sessile organisms. Sponges lack true tissues but show coordinated cellular behavior. Recognizing development type helps in comparative embryology, phylogeny, and ecological adaptation. Indirect development provides evolutionary insight into primitive metazoan life cycles.

7. Assertion-Reason MCQ:
Assertion (A): Tapeworms are hermaphroditic with internal fertilization.
Reason (R): Segments contain both male and female reproductive organs allowing self-fertilization.
(A) Both A and R are true, and R is the correct explanation of A
(B) Both A and R are true, but R is not the correct explanation of A
(C) A is true, R is false
(D) A is false, R is true
Explanation: Option (A) is correct. Tapeworms possess hermaphroditic proglottids with both reproductive systems, enabling internal fertilization within host intestines. This adaptation ensures reproduction in constrained habitats. It demonstrates evolutionary strategies of parasitic flatworms, survival in host-dependent environments, and specialization of reproductive anatomy for propagation. The reason directly explains the assertion and highlights parasitic adaptation to intestinal life.

8. Matching Type MCQ: Match organisms with features:
1. Platyhelminthes    A. Diploblastic, bioluminescent
2. Ctenophores    B. Triploblastic, bilateral, acoelomate
3. Sponges    C. External fertilization, indirect development
(A) 1-B, 2-A, 3-C
(B) 1-A, 2-B, 3-C
(C) 1-B, 2-C, 3-A
(D) 1-C, 2-B, 3-A
Explanation: Option (A) is correct. Platyhelminthes are triploblastic, bilateral, acoelomate (1-B). Ctenophores are diploblastic, marine, bioluminescent (2-A). Sponges show external fertilization with indirect development (3-C). Matching these features highlights structural, reproductive, and developmental adaptations. Correct associations help in taxonomy, understanding evolutionary relationships, and functional morphology of invertebrates, providing a framework for comparative zoology and ecological understanding.

9. Fill in the Blanks / Completion MCQ: Ctenophores are _______ and bioluminescent.
(A) Diploblastic
(B) Triploblastic
(C) Acoelomate
(D) Pseudocoelomate
Explanation: Diploblastic is correct. Ctenophores possess two germ layers, ectoderm and endoderm. They lack a mesoderm and coelom, making them structurally simpler than triploblastic animals. Bioluminescence aids predation and defense. Diploblastic organization represents primitive tissue differentiation. Understanding germ layer composition is essential for taxonomy, evolutionary biology, and functional adaptations in early metazoans, highlighting morphological simplicity and marine ecological specialization.

10. Choose the correct statements MCQ:
Statement I: Platyhelminthes are triploblastic and acoelomate.
Statement II: Ctenophores are diploblastic and marine.
(A) Both I and II are correct
(B) Only I is correct
(C) Only II is correct
(D) Neither I nor II is correct
Explanation: Option (A) is correct. Platyhelminthes are triploblastic, acoelomate, and bilateral. Ctenophores are diploblastic, exclusively marine, and bioluminescent. Both statements reflect accurate structural and ecological characteristics. Recognizing these features aids in understanding evolutionary trends, tissue complexity, and reproductive strategies among invertebrates. Accurate knowledge of germ layers and habitat specialization is fundamental for comparative zoology, phylogeny, and ecological adaptation studies.

Topic: Classification of Insects; Subtopic: Order Diptera and Its Families

Keyword Definitions:

• Diptera: An order of insects characterized by having a single pair of wings and compound eyes, including flies and mosquitoes.

• Muscidae: A family of Diptera that includes houseflies, stable flies, and related species.

• Calliphoridae: The blowfly family known for metallic coloration and association with decaying matter.

• Housefly (Musca domestica): A common synanthropic insect belonging to the family Muscidae, often found in human habitats.

• Proboscis: A tubular feeding structure used by Dipterans to suck fluids.

• Metamorphosis: Developmental transformation in insects from larval to adult stage.

• Larva: Immature form of an insect that undergoes metamorphosis.

Lead Question - 2023 (Manipur)

House fly belongs to _______ family.
1. Cyprinidae
2. Hominidae
3. Calliphoridae
4. Muscidae

Explanation: The housefly, scientifically known as Musca domestica, belongs to the family Muscidae under the order Diptera. This family includes small to medium-sized flies with sponging mouthparts. They undergo complete metamorphosis with egg, larva, pupa, and adult stages. Cyprinidae includes fishes, while Hominidae represents humans and great apes. The correct answer is Muscidae.

Guessed Question 1: Which of the following insects belongs to the order Diptera?

1. Butterfly
2. Mosquito
3. Honey bee
4. Termite

Explanation: Mosquito belongs to the order Diptera, characterized by a single pair of functional wings and halteres for balance. Butterflies belong to Lepidoptera, bees to Hymenoptera, and termites to Isoptera. Dipterans are known for rapid reproduction and act as important disease vectors in various ecosystems and human habitats.

Guessed Question 2: The scientific name of the common housefly is:

1. Musca domestica
2. Anopheles stephensi
3. Drosophila melanogaster
4. Culex pipiens

Explanation: The scientific name of the housefly is Musca domestica. It is one of the most common species of the family Muscidae. It acts as a carrier of several pathogens causing cholera, typhoid, and dysentery. Other listed species belong to mosquitoes and fruit flies, not to Muscidae.

Guessed Question 3: Which characteristic is typical of Dipteran insects?

1. Two pairs of wings
2. Single pair of wings and halteres
3. No wings
4. Scaly wings

Explanation: Dipteran insects possess a single pair of functional forewings, while their hindwings are modified into small balancing organs called halteres. This adaptation helps in stability during flight. The term Diptera literally means “two-winged.” Butterflies, having scaly wings, belong to Lepidoptera, not Diptera.

Guessed Question 4: The mouthparts of houseflies are adapted for:

1. Biting and chewing
2. Piercing and sucking
3. Sponging and lapping
4. Chewing and biting

Explanation: Houseflies have sponging and lapping type mouthparts designed to suck up liquid or semi-liquid food. The proboscis functions as a sponge, absorbing nutrients from moist surfaces. They lack mandibles and cannot bite. Mosquitoes, on the other hand, have piercing and sucking mouthparts for feeding on blood.

Guessed Question 5: The developmental stages of housefly include:

1. Egg → Larva → Nymph → Adult
2. Egg → Larva → Pupa → Adult
3. Egg → Pupa → Nymph → Adult
4. Egg → Nymph → Adult

Explanation: The housefly undergoes holometabolous metamorphosis, which includes four distinct stages — egg, larva, pupa, and adult. The larval stage, called maggot, is legless and feeds on organic matter. The pupal stage is inactive but crucial for transformation into the adult fly capable of flight and reproduction.

Guessed Question 6: Which of the following is a disease transmitted by houseflies?

1. Malaria
2. Typhoid
3. Plague
4. Yellow fever

Explanation: Houseflies are mechanical carriers of typhoid, cholera, and dysentery. They transmit pathogens from garbage and feces to human food. Malaria and yellow fever are transmitted by mosquitoes, and plague by rat fleas. Therefore, typhoid is among the major diseases spread by houseflies in unsanitary conditions.

Assertion-Reason Type Question:

Assertion (A): Houseflies can transmit diseases mechanically.
Reason (R): They carry pathogens only through bites.

1. Both A and R are true, and R is the correct explanation of A.
2. Both A and R are true, but R is not the correct explanation of A.
3. A is true, but R is false.
4. A is false, but R is true.

Explanation: Houseflies transmit diseases mechanically by carrying pathogens on their body, legs, and mouthparts. They do not bite humans as their mouthparts are sponging type. Therefore, the assertion is true but the reason is false. They contaminate food directly, causing several gastrointestinal diseases.

Matching Type Question:

Match the following insects with their respective orders:
A. Housefly
B. Honey bee
C. Butterfly
D. Mosquito

1. Diptera
2. Hymenoptera
3. Lepidoptera
4. Diptera

Codes: A-1, B-2, C-3, D-4

Explanation: Housefly and mosquito both belong to Diptera, honey bee belongs to Hymenoptera, and butterfly belongs to Lepidoptera. Dipterans have one pair of wings and halteres, whereas Lepidopterans have scaly wings and undergo complete metamorphosis. Hymenopterans are social insects with complex colony structures.

Fill in the Blanks Type Question:

The larval form of a housefly is called _______.

1. Caterpillar
2. Maggot
3. Grub
4. Nymph

Explanation: The larval stage of a housefly is known as a maggot. Maggots are soft-bodied, legless larvae that feed voraciously on decaying organic matter. This stage plays an important ecological role in decomposition. After feeding, maggots pupate and transform into adult houseflies through complete metamorphosis.

Choose the Correct Statements Type Question:

Statement I: Houseflies have sponging mouthparts.
Statement II: Houseflies transmit malaria through bites.

1. Both statements are true.
2. Both statements are false.
3. Statement I is true, Statement II is false.
4. Statement I is false, Statement II is true.

Explanation: Statement I is true as houseflies possess sponging and lapping type mouthparts adapted for consuming liquids. Statement II is false because they do not transmit malaria; mosquitoes do. Instead, houseflies mechanically transmit diseases like typhoid and cholera by contaminating food with pathogens.

Topic: Chordates - Mammals
Subtopic: Unique Mammalian Characteristics

Keyword Definitions:
Hairs: Filamentous structures on mammalian skin for insulation, sensation, and protection.
Pinna: External ear structure that helps in collecting sound waves.
Indirect development: Development involving larval stages or metamorphosis (less common in mammals).
Monocondylic skull: Skull with a single occipital condyle for articulation with the vertebral column.
Mammary glands: Specialized exocrine glands producing milk to nourish offspring.
Tympanic membrane: Eardrum separating outer and middle ear, aiding in hearing.
Chordates: Animals with a notochord, dorsal nerve cord, pharyngeal gill slits, and post-anal tail.
Vertebrates: Chordates with a backbone protecting the spinal cord.
Thermoregulation: Maintenance of stable internal temperature, aided by hair and fat.
Endothermic: Ability to generate internal heat to maintain body temperature.
Viviparous: Animals giving birth to live young, characteristic of most mammals.

Lead Question (2023):
The unique mammalian characteristics are:
(1) hairs, pinna and indirect development
(2) Pinna, monocondylic skull and mammary glands
(3) hairs, tympanic membrane and mammary glands
(4) hairs, pinna and mammary glands

Answer & Explanation: Option 4 is correct. Mammals are distinguished by the presence of hair, external pinna, and mammary glands. Hair provides insulation and sensory input, pinna helps in capturing sound waves efficiently, and mammary glands produce milk for offspring. While tympanic membrane and monocondylic skull are features present in mammals, they are not as uniquely characteristic as these three features. Indirect development is not typical in mammals, which mostly exhibit viviparity and direct development. Together, these traits define the mammalian class and differentiate them from other vertebrates such as birds and reptiles.

1. Single Correct Answer MCQ: Which structure helps mammals in efficient hearing of sound waves?
A) Tympanic membrane
B) Pinna
C) Hair
D) Mammary gland

Answer & Explanation: Option B is correct. Pinna is the external ear structure that collects sound waves and directs them into the auditory canal. Tympanic membrane converts sound waves into vibrations but pinna is unique in its external shape in mammals. Hair and mammary glands are unrelated to sound perception.

2. Single Correct Answer MCQ: Mammary glands in mammals are responsible for:
A) Reproduction
B) Milk production
C) Hair growth
D) Hearing

Answer & Explanation: Option B is correct. Mammary glands are specialized exocrine glands producing milk to nourish young ones, ensuring survival and proper growth. They are unique to mammals. Hair growth, hearing, or reproductive functions are carried out by different organs.

3. Single Correct Answer MCQ: Which of the following is NOT a unique mammalian feature?
A) Hair
B) Pinna
C) Mammary glands
D) Indirect development

Answer & Explanation: Option D is correct. Indirect development with larval stages is not typical in mammals; they exhibit direct development and viviparity. Hair, pinna, and mammary glands are distinctive mammalian traits, providing thermoregulation, sound perception, and nourishment to offspring.

4. Single Correct Answer MCQ: Hair in mammals primarily serves for:
A) Reproduction
B) Insulation and sensory input
C) Milk secretion
D) Sound detection

Answer & Explanation: Option B is correct. Hair provides insulation to maintain body temperature and acts as a sensory organ detecting mechanical stimuli. It is a unique adaptation among mammals for thermoregulation and environmental sensing.

5. Single Correct Answer MCQ: Tympanic membrane in mammals functions to:
A) Detect sound waves
B) Produce milk
C) Support hair growth
D) Assist in reproduction

Answer & Explanation: Option A is correct. Tympanic membrane, or eardrum, vibrates in response to sound waves transmitting vibrations to middle ear ossicles. While important in hearing, it is present in other vertebrates and thus not unique to mammals.

6. Single Correct Answer MCQ: Which skull feature is present in most mammals?
A) Monocondylic skull
B) Bicondylic skull
C) Diapsid skull
D) Anapsid skull

Answer & Explanation: Option B is correct. Most mammals have a bicondylic skull with two occipital condyles, providing stability and flexibility at the joint with vertebrae. Monocondylic, diapsid, or anapsid skulls are characteristic of other vertebrate groups like reptiles.

7. Assertion-Reason MCQ:
Assertion (A): Mammary glands are unique to mammals.
Reason (R): They produce milk to nourish offspring.
A) Both A and R are true and R is the correct explanation of A
B) Both A and R are true but R is not the correct explanation of A
C) A is true but R is false
D) A is false but R is true

Answer & Explanation: Option A is correct. Mammary glands are unique mammalian organs, and their primary function is to secrete milk for offspring nutrition. This is the defining characteristic that supports survival of mammalian young.

8. Matching Type MCQ:
Match the mammalian feature with its function:
List I - List II
A. Hair - I. Insulation and sensation
B. Pinna - II. Hearing and sound collection
C. Mammary glands - III. Milk production
Choose correct option:
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

Answer & Explanation: Option 1 is correct. Hair provides insulation and sensory functions, pinna collects and directs sound waves, and mammary glands produce milk. This combination of features differentiates mammals from other vertebrates and supports survival and reproductive success.

9. Fill in the Blanks MCQ: The external ear of mammals is called ________ and helps in ________.
A) Pinna; sound collection
B) Tympanic membrane; hearing
C) Hair; insulation
D) Mammary gland; nutrition

Answer & Explanation: Option A is correct. Pinna is the external ear structure that collects sound waves and directs them to the auditory canal. Tympanic membrane transmits vibrations but pinna is uniquely adapted for external sound collection.

10. Choose the Correct Statements MCQ:
Statement I: Mammals are endothermic and have hair.
Statement II: Mammary glands secrete milk to nourish offspring.
A) Both statements are correct
B) Both statements are incorrect
C) Only Statement I is correct
D) Only Statement II is correct

Answer & Explanation: Option A is correct. Mammals are endothermic, with hair aiding in insulation and sensory function. Mammary glands produce milk for offspring nutrition. Both traits are unique mammalian adaptations that support thermoregulation, reproduction, and survival of young.

Topic: Chordates; Subtopic: General Characteristics of Chordates

Keyword Definitions:
Chordates: Animals possessing a notochord, dorsal nerve cord, pharyngeal gill slits, post-anal tail, and endostyle at some stage of life.
Notochord: A flexible rod-like structure that provides skeletal support in embryos and some adult chordates.
Dorsal nerve cord: Hollow tube located dorsally above the notochord, forming the central nervous system.
Pharyngeal gill slits: Openings in the pharynx for filter-feeding or respiration in aquatic chordates.
Triploblastic: Animals with three germ layers: ectoderm, mesoderm, and endoderm.
Pseudocoelomate: Animals with a body cavity partially lined with mesoderm.
Closed circulatory system: Blood circulates within vessels, ensuring efficient transport of nutrients and gases.
Dorsal heart: Heart located dorsally, present in some chordates like tunicates.
Post-anal tail: Tail extending beyond the anus, aiding in locomotion.
Endostyle: Ciliated groove in pharynx secreting mucus to trap food particles.
Embryonic development: Formation of body plan and germ layers during early life stages.

Lead Question (2023):
Select the correct statements with reference to chordates.
A. Presence of a mid-dorsal, solid and double nerve cord.
B. Presence of closed circulatory system.
C. Presence of paired pharyngeal gill slits.
D. Presence of dorsal heart.
E. Triploblastic pseudocoelomate animals.
Choose the correct answer from the options given below:
(1) B, D and E only
(2) C, D and E only
(3) A, C and D only
(4) B and C only

Answer & Explanation: Option 3 is correct. Chordates possess a dorsal hollow nerve cord, not solid and double, paired pharyngeal gill slits, and a dorsal heart in some invertebrate chordates like tunicates. They are triploblastic and coelomate, not pseudocoelomate. Closed circulatory system is present in vertebrates. These features distinguish chordates from non-chordates and pseudocoelomates, allowing locomotion, filter-feeding, efficient circulation, and neural coordination essential for survival, development, and evolution of complex organ systems in this phylum.

1. Single Correct Answer MCQ: The notochord in chordates functions primarily as:
A) Digestive organ
B) Skeletal support
C) Respiratory organ
D) Circulatory organ

Answer & Explanation: Option B is correct. The notochord is a flexible rod that provides axial support and resists compression during movement. It is present in embryos of all chordates and persists in adult forms of some invertebrate chordates. It guides development of vertebral column in vertebrates, ensuring structural integrity and proper organization of body axis, muscle attachment, and locomotion.

2. Single Correct Answer MCQ: Which feature is unique to chordates among animals?
A) Ventral nerve cord
B) Post-anal tail
C) Radial symmetry
D) Exoskeleton

Answer & Explanation: Option B is correct. The post-anal tail is a chordate characteristic present at least in embryonic stages, aiding in swimming and locomotion. Non-chordates typically lack this feature. Ventral nerve cord is found in many invertebrates, radial symmetry occurs in cnidarians and echinoderms, and exoskeleton is seen in arthropods. This feature helps in identification and classification of chordates.

3. Single Correct Answer MCQ: In chordates, pharyngeal gill slits are primarily used for:
A) Digestion
B) Respiration or filter-feeding
C) Locomotion
D) Excretion

Answer & Explanation: Option B is correct. Pharyngeal gill slits in aquatic chordates serve as openings for water to pass during filter-feeding and gas exchange. In terrestrial vertebrates, they are modified during embryonic development. This feature is fundamental for respiration in fish and aids in evolutionary adaptation, highlighting functional versatility in chordate pharyngeal structures.

4. Single Correct Answer MCQ: The circulatory system of vertebrate chordates is:
A) Open
B) Closed
C) Absent
D) Partially closed

Answer & Explanation: Option B is correct. Vertebrate chordates possess a closed circulatory system, where blood circulates entirely within vessels, allowing efficient oxygen and nutrient transport. Invertebrate chordates may have simpler circulatory mechanisms. Closed circulation ensures high-pressure flow, tissue oxygenation, and metabolic regulation, which are critical for activity levels, growth, and survival of complex vertebrate organisms.

5. Single Correct Answer MCQ: Which chordate structure develops into the vertebral column in vertebrates?
A) Notochord
B) Dorsal nerve cord
C) Pharyngeal slit
D) Post-anal tail

Answer & Explanation: Option A is correct. The notochord provides axial support and serves as a scaffold for vertebral column formation during embryogenesis in vertebrates. The dorsal nerve cord forms the spinal cord, pharyngeal slits contribute to gill arches, and the post-anal tail aids locomotion. Notochord's role is crucial for structural development and evolutionary progression of chordates.

6. Single Correct Answer MCQ: Which chordate class possesses a dorsal hollow nerve cord throughout life?
A) Mammals
B) Amphibians
C) Cephalochordata
D) Arthropoda

Answer & Explanation: Option C is correct. Cephalochordates (like Amphioxus) retain a dorsal hollow nerve cord throughout life. Vertebrates have it during embryonic stages, with modifications in the central nervous system. Arthropods have ventral nerve cords. This feature is essential for neural signaling, body coordination, and distinguishing chordates from non-chordate invertebrates in taxonomy and comparative anatomy.

7. Assertion-Reason MCQ:
Assertion (A): Chordates are triploblastic coelomates.
Reason (R): They possess three germ layers and a true coelomic cavity.
A) Both A and R are true and R is the correct explanation of A
B) Both A and R are true but R is not the correct explanation of A
C) A is true but R is false
D) A is false but R is true

Answer & Explanation: Option A is correct. Chordates develop from three germ layers (ectoderm, mesoderm, endoderm) and have a true coelomic cavity lined with mesoderm, facilitating organ development and complex organ systems. Triploblastic coelomate condition allows advanced body organization, efficient circulation, and structural support, distinguishing chordates from pseudocoelomates and acoelomates in evolutionary terms.

8. Matching Type MCQ: Match structures with their functions:
List I - List II
A. Notochord - I. Axial support
B. Pharyngeal slits - II. Filter-feeding/respiration
C. Dorsal nerve cord - III. Neural coordination
Choose correct option:
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

Answer & Explanation: Option 1 is correct. Notochord provides axial support (A-I), pharyngeal slits assist in filter-feeding or respiration (B-II), and the dorsal nerve cord facilitates neural coordination (C-III). These fundamental chordate characteristics ensure structural integrity, respiratory efficiency, and nervous control, aiding in survival, locomotion, and evolutionary adaptation within the phylum.

9. Fill in the Blanks MCQ: Chordates have a ________ heart in invertebrate forms like tunicates.
A) Ventral
B) Dorsal
C) Lateral
D) Absent

Answer & Explanation: Option B is correct. In some invertebrate chordates, such as tunicates, the heart is dorsal, unlike the ventral position in most non-chordates. The dorsal heart pumps blood efficiently in the closed or open circulatory system, supporting nutrient and oxygen transport, demonstrating a unique chordate adaptation for circulation and survival.

10. Choose the Correct Statements MCQ:
Statement I: Chordates have a dorsal hollow nerve cord.
Statement II: Chordates are pseudocoelomate animals.
A) Both statements are correct
B) Both statements are incorrect
C) Only Statement I is correct
D) Only Statement II is correct

Answer & Explanation: Option C is correct. Chordates possess a dorsal hollow nerve cord, a defining characteristic. They are triploblastic coelomates, not pseudocoelomates. Recognizing these features is essential for distinguishing chordates from other animal phyla, understanding developmental biology, embryonic structures, and evolutionary relationships, which are fundamental in comparative anatomy and zoological classification.

Topic: Excretory Systems; Subtopic: Types of Excretory Organs in Animals

Lead Question - 2023

Match List I with List II.
List I | List II
A. Taenia | I. Nephridia
B. Paramoecium | II. Contractile vacuole
C. Periplaneta | III. Flame cells
D. Pheretima | IV. Urecose gland
Choose the correct answer from the options given below:
(1) A-III, B-II, C-IV, D-I
(2) A-II, B-I, C-IV, D-III
(3) A-I, B-II, C-III, D-IV
(4) A-I, B-II, C-IV, D-III

Answer: (1) A-III, B-II, C-IV, D-I. In Taenia, excretion occurs through flame cells (protonephridia). Paramoecium uses contractile vacuoles to expel excess water. Periplaneta (cockroach) has urecose glands for excretion, while Pheretima (earthworm) uses nephridia to remove metabolic waste. Each excretory structure is adapted to the habitat and osmotic needs of the organism, ensuring proper removal of nitrogenous wastes and maintenance of internal homeostasis.

Keyword Definitions:

• Taenia: A parasitic flatworm which excretes nitrogenous waste via flame cells.

• Paramoecium: Unicellular ciliate protozoan, uses contractile vacuole to maintain osmotic balance.

• Periplaneta: Cockroach, insect with urecose glands for excretion.

• Pheretima: Earthworm, annelid with nephridia to remove metabolic waste.

• Flame cells: Specialized excretory cells found in flatworms for osmoregulation.

• Contractile vacuole: Organelle that pumps out excess water from protozoans.

• Nephridia: Tubular excretory organ in annelids for nitrogenous waste removal.

• Urecose gland: Excretory structure in insects to remove nitrogenous waste.

1. Single Correct Answer:

Which excretory structure is present in flatworms?
(1) Nephridia
(2) Urecose gland
(3) Flame cells
(4) Contractile vacuole

Answer: (3) Flame cells. Flatworms like Taenia use flame cells for excretion and osmoregulation, expelling nitrogenous wastes and excess water through a network of tubules.

2. Single Correct Answer:

Contractile vacuoles are found in:
(1) Earthworm
(2) Paramoecium
(3) Cockroach
(4) Taenia

Answer: (2) Paramoecium. Contractile vacuoles expel excess water to maintain osmotic balance in freshwater protozoans like Paramoecium, preventing cell lysis.

3. Single Correct Answer:

Nephridia are characteristic of:
(1) Taenia
(2) Paramoecium
(3) Pheretima
(4) Periplaneta

Answer: (3) Pheretima. Earthworms have nephridia for excreting nitrogenous waste, removing urea and other metabolic products while maintaining osmotic balance in soil environments.

4. Single Correct Answer:

Urecose glands are found in:
(1) Paramoecium
(2) Cockroach
(3) Taenia
(4) Earthworm

Answer: (2) Cockroach. Insects like Periplaneta possess urecose glands that eliminate nitrogenous wastes and regulate water balance in the hemolymph.

5. Single Correct Answer:

Flame cells primarily function in:
(1) Digestion
(2) Osmoregulation
(3) Respiration
(4) Locomotion

Answer: (2) Osmoregulation. Flame cells in flatworms regulate water content and excrete nitrogenous wastes, aiding in maintaining internal osmotic balance in freshwater environments.

6. Single Correct Answer:

Which excretory organ helps freshwater protozoans remove excess water?
(1) Nephridia
(2) Flame cells
(3) Contractile vacuole
(4) Urecose gland

Answer: (3) Contractile vacuole. In Paramoecium, contractile vacuoles pump out excess water entering by osmosis to prevent cell swelling and maintain cytoplasmic balance.

7. Assertion-Reason:

Assertion A: Earthworms possess nephridia.
Reason R: Nephridia excrete metabolic wastes in annelids.
(1) A true, R false
(2) A false, R true
(3) Both true, R explains A
(4) Both true, R does not explain A

Answer: (3) Both true, R explains A. Earthworms have nephridia that remove nitrogenous wastes and regulate internal water balance, supporting metabolic homeostasis.

8. Matching Type:

Match animals with their excretory structures:
List I | List II
A. Taenia | I. Flame cells
B. Paramoecium | II. Contractile vacuole
C. Pheretima | III. Nephridia
D. Periplaneta | IV. Urecose gland
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

Answer: (1) A-I, B-II, C-III, D-IV. Taenia uses flame cells, Paramoecium uses contractile vacuoles, Pheretima has nephridia, and Periplaneta uses urecose glands.

9. Fill in the Blanks:

The excretory organ of cockroach is ________.
Options: (1) Nephridia (2) Flame cells (3) Urecose gland (4) Contractile vacuole

Answer: (3) Urecose gland. Periplaneta utilizes urecose glands to remove nitrogenous wastes and maintain osmotic homeostasis.

Topic: Body Symmetry in Animals; Subtopic: Radial and Bilateral Symmetry

Keyword Definitions:

• Symmetry: Arrangement of body parts around a central axis or plane, giving a balanced form.

• Radial Symmetry: Body parts arranged around a central axis; found in sedentary or sessile animals like jellyfish.

• Bilateral Symmetry: Body divided into two identical halves along a single plane, aiding locomotion.

• Echinodermata: Marine animals with radial symmetry in adults but bilateral symmetry in larvae.

• Hemichordata: Bilaterally symmetrical marine organisms related to chordates, showing worm-like bodies.

Lead Question - 2023

Radial symmetry is NOT found in adults of phylum _________.
(1) Coelenterata
(2) Echinodermata
(3) Ctenophora
(4) Hemichordata

Answer & Explanation: (4) Hemichordata. Adult Hemichordates show bilateral symmetry, unlike Coelenterates, Ctenophores, and Echinoderms which exhibit radial symmetry. Hemichordates possess a body divided into proboscis, collar, and trunk, facilitating burrowing and movement in one direction. This symmetry aids in centralized nervous system development, improving sensory coordination and environmental interaction in their marine habitats.

1. Which of the following animals shows bilateral symmetry?

(1) Hydra
(2) Starfish
(3) Planaria
(4) Jellyfish

Planaria exhibits bilateral symmetry, allowing only one plane to divide its body into equal halves. This type of symmetry supports cephalization and directional movement. Bilateral symmetry is a major evolutionary advancement in animals, enabling streamlined locomotion and better sensory perception, common in Platyhelminthes, Annelids, Arthropods, and Chordates.

2. In which group of animals is radial symmetry found only in adults?

(1) Echinodermata
(2) Coelenterata
(3) Ctenophora
(4) Porifera

Echinodermata exhibit radial symmetry in adults and bilateral symmetry in larvae. This shift during metamorphosis represents evolutionary adaptation. Radial symmetry suits their sedentary lifestyle, enabling environmental interaction from all directions, while bilateral larval form supports motility during dispersal, ensuring successful survival and colonization.

3. Which phylum includes animals with biradial symmetry?

(1) Ctenophora
(2) Coelenterata
(3) Annelida
(4) Mollusca

Ctenophora exhibit biradial symmetry, a combination of radial and bilateral types. Their body can be divided into identical halves only by two planes. This structural arrangement, seen in comb jellies, allows efficient swimming and prey capture through coordinated ciliary movement and luminescent structures.

4. Assertion-Reason Type:

Assertion (A): Adult Echinoderms show radial symmetry.
Reason (R): Radial symmetry allows uniform response to stimuli from all directions.
(1) Both A and R are true and R explains A.
(2) Both A and R are true but R does not explain A.
(3) A is true but R is false.
(4) A is false but R is true.

Both A and R are true, and R correctly explains A. Adult Echinoderms are sessile or slow-moving, and radial symmetry enables them to sense and respond to environmental stimuli equally from all directions. It also aids in food capture and protection, suiting their benthic lifestyle.

5. Fill in the blanks:

Adult starfish shows ______ symmetry, while its larva shows ______ symmetry.
(1) Radial, Bilateral
(2) Bilateral, Radial
(3) Asymmetrical, Radial
(4) Radial, Asymmetrical

Adult starfish shows radial symmetry, while its larva shows bilateral symmetry. The bilateral larval stage supports free-swimming life, whereas the adult’s radial symmetry helps in sedentary or crawling movement. This developmental transition illustrates evolutionary adaptation to distinct ecological niches in the life cycle of Echinoderms.

6. Which phylum lacks any definite body symmetry?

(1) Porifera
(2) Echinodermata
(3) Coelenterata
(4) Ctenophora

Phylum Porifera lacks definite symmetry, as sponges exhibit asymmetrical body organization. Their irregular shapes result from constant growth and pore distribution for water circulation. This simple structural plan supports filter feeding and respiration without dependence on directional body organization.

7. Matching Type:

List I – Phylum
A. Porifera
B. Coelenterata
C. Ctenophora
D. Echinodermata

List II – Type of Symmetry
I. Radial
II. Asymmetrical
III. Biradial
IV. Radial (Adult)

(1) A-II, B-I, C-III, D-IV
(2) A-I, B-II, C-IV, D-III
(3) A-II, B-IV, C-I, D-III
(4) A-III, B-I, C-II, D-IV

The correct match is A-II, B-I, C-III, D-IV. Porifera are asymmetrical, Coelenterata show radial symmetry, Ctenophora are biradial, and Echinodermata are radially symmetrical as adults. This progression of symmetry reflects evolutionary specialization in structure and function across animal phyla.

8. Choose the correct statements:

Statement I: Bilateral symmetry aids directional movement.
Statement II: Radial symmetry benefits sessile organisms.
(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

Both statements are correct. Bilateral symmetry enhances streamlined movement and coordination, while radial symmetry benefits sessile or slow-moving animals by enabling equal response to stimuli from all directions, promoting feeding and defense efficiency.

9. Which of the following is an example of a radially symmetrical organism?

(1) Jellyfish
(2) Earthworm
(3) Leech
(4) Planaria

Jellyfish exhibits radial symmetry. Its body is organized around a central axis with tentacles extending outward. This arrangement enables uniform interaction with the environment and is ideal for floating and capturing prey from all sides in aquatic ecosystems.

10. Which of the following shows transition from bilateral to radial symmetry during development?

(1) Echinodermata
(2) Coelenterata
(3) Hemichordata
(4) Ctenophora

Echinodermata transition from bilateral larval forms to radially symmetrical adults. This ontogenetic change supports adaptation from motile larval dispersal to sedentary adult life. It highlights evolutionary modification within deuterostomes, linking them developmentally to chordates through shared embryonic features and symmetry shift.

Chapter: Animal Diversity; Topic: Pisces; Subtopic: Cyclostomes

Keyword Definitions:
• Cyclostomes: Jawless vertebrates like lampreys and hagfish.
• Scales: Protective epidermal structures found in most fishes.
• Paired fins: Limbs present in most fishes for locomotion.
• Jaws: Bony or cartilaginous structures used for feeding.
• Gills: Respiratory organs in aquatic vertebrates for gas exchange.
• Migration: Seasonal movement of organisms for breeding or feeding.

Lead Question - 2022 (Ganganagar)

Select the Incorrect statements with respect to Cyclostomes:
(a) They lack scales and paired fins.
(b) They have circular mouth with Jaws.
(c) They bear 6-15 pairs of gills.
(d) They migrate to deep sea for spawning.
Choose the most appropriate answer from the options given below:
1. (a) and (b) only
2. (b) and (c) only
3. (b) and (d) only
4. (a) and (d) only

Explanation: The correct answer is option 3. Cyclostomes are jawless vertebrates that lack paired fins and scales, and they have a circular, sucker-like mouth without true jaws. They typically bear 6–15 pairs of gill pouches depending on the species. Some, like lampreys, migrate for spawning, but not necessarily to the deep sea. Therefore, statements (b) and (d) are incorrect: (b) is wrong because cyclostomes have no jaws, and (d) is wrong because migration is generally upstream to freshwater rather than deep sea.

1. Single Correct Answer MCQ:
Which of the following is a jawless fish?
1. Scoliodon
2. Labeo
3. Lamprey
4. Clarias

Explanation: The correct answer is Lamprey. Lampreys are cyclostomes and lack jaws, paired fins, and scales. They have a circular, sucker-like mouth used for attaching to host fishes. Other fishes listed, such as Scoliodon (shark), Labeo, and Clarias, possess jaws and paired fins and are not jawless.

2. Single Correct Answer MCQ:
Cyclostomes possess:
1. Paired fins
2. Jaws
3. Circular mouth
4. Scales

Explanation: The correct answer is circular mouth. Cyclostomes have a round, sucker-like mouth adapted for attachment and feeding on host tissues or scavenging. They do not have paired fins, scales, or true jaws. This adaptation is a key feature distinguishing them from other jawed fishes.

3. Single Correct Answer MCQ:
Number of gill pouches typically present in cyclostomes:
1. 2-4 pairs
2. 6-15 pairs
3. 20-25 pairs
4. None

Explanation: The correct answer is 6–15 pairs. Cyclostomes like lampreys and hagfish have multiple gill pouches (commonly 6–15) used for respiration. This differs from jawed fishes, which have a single gill slit on each side covered by operculum.

4. Single Correct Answer MCQ:
Cyclostomes migrate primarily for:
1. Feeding in open sea
2. Spawning in freshwater
3. Shelter in coral reefs
4. Seasonal hibernation

Explanation: The correct answer is spawning in freshwater. Many cyclostomes, such as lampreys, are anadromous and migrate from marine to freshwater habitats for reproduction. They do not migrate to deep sea or coral reefs and do not hibernate seasonally.

5. Single Correct Answer MCQ:
Which structure is absent in cyclostomes?
1. Notochord
2. Paired fins
3. Gill pouches
4. Heart

Explanation: The correct answer is paired fins. Cyclostomes possess a notochord and a simple two-chambered heart, along with multiple gill pouches, but lack paired fins. This primitive anatomy reflects their jawless and basal vertebrate status.

6. Single Correct Answer MCQ:
Hagfish differs from lamprey in that it:
1. Has jaws
2. Is marine only
3. Possesses paired fins
4. Has circular mouth

Explanation: The correct answer is marine only. Hagfish are marine cyclostomes and do not migrate to freshwater, whereas lampreys are anadromous. Both have circular mouths and lack jaws and paired fins.

7. Assertion-Reason MCQ:
Assertion (A): Cyclostomes are jawless fishes.
Reason (R): They have circular mouths and lack paired fins.
1. Both A and R are correct and R explains A
2. Both A and R are correct but R does not explain A
3. A correct, R incorrect
4. A incorrect, R correct

Explanation: The correct answer is option 1. Cyclostomes lack jaws, which is a defining characteristic. They also have circular, sucker-like mouths and lack paired fins, supporting their primitive anatomy. The reason correctly explains the assertion.

8. Matching Type MCQ:
Match the cyclostome with its habitat:
(a) Lamprey - (i) Marine and freshwater
(b) Hagfish - (ii) Marine only

1. (a)-(i), (b)-(ii)
2. (a)-(ii), (b)-(i)
3. (a)-(i), (b)-(i)
4. (a)-(ii), (b)-(ii)

Explanation: The correct answer is option 1. Lampreys are anadromous, living in both marine and freshwater, migrating to freshwater for spawning. Hagfish are strictly marine and remain in deep sea environments.

9. Fill in the Blanks MCQ:
Cyclostomes are __________ vertebrates with __________ mouths.

1. Jawless, circular
2. Jawed, triangular
3. Jawless, jaws
4. Jawed, circular

Explanation: The correct answer is jawless, circular. Cyclostomes are primitive vertebrates without jaws, and their mouth is circular and adapted for suction feeding or parasitism.

10. Choose the Correct Statements MCQ:
Statement I: Cyclostomes lack jaws and paired fins.
Statement II: Cyclostomes have 6–15 pairs of gill pouches.

1. Only Statement I correct
2. Only Statement II correct
3. Both correct
4. Both incorrect

Explanation: The correct answer is option 3. Cyclostomes are jawless vertebrates that lack paired fins. They possess multiple gill pouches, typically ranging from 6 to 15 pairs, which function in respiration. Both statements are correct.

Topic: Circulatory System; Subtopic: Heart Structure in Vertebrates

Keyword Definitions:
• Three-chambered heart: A heart with two atria and one ventricle, found in amphibians and most reptiles.
• Scoliodon: A genus of cartilaginous fish (sharks) with a two-chambered heart.
• Hippocampus: A genus of marine fish (seahorses) with two-chambered heart.
• Chelone: Turtles, reptiles having a three-chambered heart (except crocodilians).
• Pteropus: Bats, mammals with four-chambered heart.
• Heart Chambers: Compartments in the heart that receive and pump blood to maintain circulation.

Lead Question - 2022 (Ganganagar)

Which of the following animals has three chambered heart?
1. Scoliodon
2. Hippocampus
3. Chelone
4. Pteropus

Explanation: The correct answer is Chelone. Turtles, which belong to reptiles, have a three-chambered heart consisting of two atria and one ventricle. This allows partial mixing of oxygenated and deoxygenated blood, suitable for their ectothermic metabolism. Scoliodon and Hippocampus, being fish, have a two-chambered heart with one atrium and one ventricle. Pteropus, a mammal, has a four-chambered heart with complete separation of oxygenated and deoxygenated blood, unlike reptiles.

1. The number of atria in a three-chambered heart is:
1. One
2. Two
3. Three
4. Four

Explanation: The correct answer is two. A three-chambered heart has two atria and one ventricle. This arrangement allows separation of oxygenated and deoxygenated blood in atria, but the single ventricle causes partial mixing. It is characteristic of most reptiles and amphibians, providing adequate circulation for ectothermic metabolism.

2. Which animal has a four-chambered heart?
1. Frog
2. Chelone
3. Crocodile
4. Scoliodon

Explanation: The correct answer is crocodile. Crocodilians are unique among reptiles with a four-chambered heart, consisting of two atria and two ventricles, allowing complete separation of oxygenated and deoxygenated blood. Frogs and Chelone have three-chambered hearts, while Scoliodon (shark) has a two-chambered heart.

3. Which feature is common to all three-chambered hearts?
1. Two ventricles
2. Two atria and one ventricle
3. Complete separation of oxygenated and deoxygenated blood
4. Single atrium

Explanation: The correct answer is two atria and one ventricle. Three-chambered hearts are found in amphibians and most reptiles, allowing partial mixing of blood in the ventricle. Complete separation occurs only in four-chambered hearts of birds and mammals.

4. Scoliodon heart type is:
1. Three-chambered
2. Two-chambered
3. Four-chambered
4. Five-chambered

Explanation: The correct answer is two-chambered. Scoliodon, a shark, has one atrium and one ventricle. Blood flows in a single circuit from heart to gills to body and back. It is characteristic of fish, supporting their aquatic respiration and circulatory needs.

5. Which is a feature of mammalian hearts like Pteropus?
1. Single atrium
2. Single ventricle
3. Four chambers with complete separation
4. Two atria and one ventricle

Explanation: The correct answer is four chambers with complete separation. Mammals, including bats like Pteropus, have two atria and two ventricles, preventing mixing of oxygenated and deoxygenated blood. This supports high metabolic rates and endothermy.

6. Chelone belongs to which class?
1. Amphibia
2. Reptilia
3. Pisces
4. Mammalia

Explanation: The correct answer is Reptilia. Chelone represents turtles, reptiles with a three-chambered heart. Amphibians like frogs also have three-chambered hearts, but reptiles have more developed heart structure. Pisces (Scoliodon, Hippocampus) have two-chambered hearts, and mammals like Pteropus have four-chambered hearts.

7. Assertion-Reason Question:
Assertion (A): Reptiles like Chelone have a three-chambered heart.
Reason (R): This allows partial mixing of oxygenated and deoxygenated blood.

1. Both A and R correct and R explains A
2. Both A and R correct but R does not explain A
3. A correct, R incorrect
4. A incorrect, R correct

Explanation: The correct answer is option 1. Chelone, a turtle, has two atria and one ventricle. The single ventricle causes partial mixing of oxygen-rich and oxygen-poor blood. This arrangement meets metabolic requirements of ectothermic reptiles while conserving energy.

8. Matching Type:
Match the animal with heart type:
(a) Scoliodon - (i) Two-chambered
(b) Chelone - (ii) Three-chambered
(c) Pteropus - (iii) Four-chambered

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

Explanation: The correct answer is option 1. Scoliodon (shark) has a two-chambered heart, Chelone (turtle) has a three-chambered heart, and Pteropus (bat) has a four-chambered heart. This illustrates the evolution of heart complexity in vertebrates.

9. Fill in the Blanks:
The heart of amphibians and most reptiles has ______ atria and ______ ventricle.

1. Two, One
2. One, Two
3. Two, Two
4. One, One

Explanation: The correct answer is two, one. Amphibians and most reptiles like Chelone have two atria and one ventricle. This allows partial mixing of blood in the ventricle, which is sufficient for their ectothermic metabolism and oxygen requirements.

10. Choose the Correct Statements:
Statement I: Chelone has a three-chambered heart.
Statement II: Scoliodon has a four-chambered heart.

1. Only Statement I correct
2. Only Statement II correct
3. Both correct
4. Both incorrect

Explanation: The correct answer is option 1. Chelone, a reptile, has two atria and one ventricle (three-chambered heart). Scoliodon, a fish, has a two-chambered heart. Statement II is incorrect, making only Statement I correct.

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