mistakes in zoology

Category	Examples

Pigments

Carotenoids, Anthocyanins

Alkaloids

Morphine, Codeine

Terpenoids

Monoterpenes, Diterpenes

Essential Oils

Lemon grass oil

Toxins

Abrin, Ricin

Lectins

Concanavalin A

Drugs

Vinblastin, Curcumin

Polymeric Substances

Rubber, Gums, Cellulose

🌱 Primary and Secondary Metabolites – NEET Summary

Feature	Primary Metabolites	Secondary Metabolites
Definition	Biomolecules involved in growth, development, and reproduction	Compounds not directly involved in physiological processes
Examples	Amino acids, sugars, nucleotides, lipids	Alkaloids, flavonoids, essential oils, antibiotics
Occurrence	Found in animal and plant cells	Mostly found in plants, fungi, microbes
Function	Known and essential roles in metabolism	Not always known, but often ecologically or medically important
Use to Humans	Basic life processes	Medicines, flavours, fragrances, colours, rubber

(Rana tigrina) 📚 Classification

• Phylum: Chordata

• Class: Amphibia

• Species (India): Rana tigrina (now called Hoplobatrachus tigerinus)

🌡 Body Temperature

• Poikilothermic (Cold-blooded):

  • Body temperature varies with the environment.

🎨 Color Change & Camouflage

• Frogs change their colour:

  • Green in grasses 🌿

  • Brown on dry land 🌾

• Purpose: Protection from predators through mimicry (camouflage).

😴 Seasonal Behavior

• Aestivation:

  • Summer sleep to escape extreme heat 🔥

• Hibernation:

  • Winter sleep to escape extreme cold ❄

• Frogs hide in deep burrows during these periods

🟢 Skin

• Smooth, slippery due to mucus.

• Always moist (helps in cutaneous respiration).

• Dorsal side: Olive green with dark irregular spots.

• Ventral side: Uniform pale yellow.

• Frogs do not drink water — they absorb it through their skin.

🟣 Body Division

• Divided into Head and Trunk (No neck, No tail).

🔵 Head Features

• Nostrils: A pair, above the mouth.

• Eyes: Bulged, with nictitating membrane (protection underwater).

• Tympanum: Membranous ear, on either side of eyes — receives sound signals.

🔴 Limbs

• Forelimbs: Shorter, end in 4 digits.

• Hindlimbs: Longer, muscular, end in 5 digits, have webbed feet (help in swimming, leaping, burrowing

🟠 Sexual Dimorphism

• Males have:

  • Vocal sacs (for croaking).

  • Copulatory pad on the first digit of forelimbs.

• Females: No vocal sacs or pads.

Vascular System:

• The vascular system in frogs is closed and well-developed.

• It consists of the heart, blood vessels, and blood. The lymphatic system also exists, comprising lymph, lymph channels, and lymph nodes.

• The heart is muscular and located in the upper part of the body cavity. It has three chambers: two atria and one ventricle, all enclosed by a membrane called the pericardium.

• A sinus venosus joins the right atrium, receiving blood through the vena cava (major veins).

• The ventricle opens into a sac-like conus arteriosus on the ventral side of the heart.

• Arterial System: Blood from the heart is carried to all parts of the body by arteries.

• Venous System: Veins collect blood from various parts of the body and return it to the heart.

• Special Venous Connections:

• Hepatic portal system: Between the liver and intestine.

  • Renal portal system: Between the kidneys and the lower body.

Blood Composition:

• Plasma and blood cells make up the blood. The blood cells include:

  • Red blood cells (RBC) or erythrocytes, which are nucleated and contain hemoglobin (red pigment).

  • White blood cells (WBC) or leucocytes and platelets.

• The lymph differs from blood in that it lacks RBCs and some proteins.

• The blood circulates nutrients, gases, and water to various body parts, and this circulation is driven by the pumping action of the heart.

Excretory System:

• The excretory system of frogs is well-developed for eliminating nitrogenous waste.

• It consists of:

  • Kidneys: Bean-shaped, dark red structures located posteriorly on both sides of the vertebral column.

  • Ureters: Two ureters emerge from the kidneys.

  • Cloaca: The common opening for excretory and reproductive systems.

  • Urinary Bladder: Thin-walled, situated ventral to the rectum, and also opens into the cloaca.

• Nephrons (urine-producing units) are present in the kidneys.

  • Frogs excrete urea, making them ureotelic animals.

• Excretion Process: Excretory wastes are carried by the blood to the kidneys, where they are filtered and excreted as urine.

Nervous and Endocrine Systems:

• Endocrine System: Chemical coordination is achieved by hormones secreted by various glands. Prominent endocrine glands in frogs include:

  • Pituitary, thyroid, parathyroid, thymus, pineal body, pancreatic islets, adrenals, and gonads.

Nervous System: Divided into three components:

1. Central Nervous System (CNS): Composed of the brain and spinal cord.

2. Peripheral Nervous System (PNS): Consists of cranial and spinal nerves.

3. Autonomic Nervous System: Includes sympathetic and parasympathetic divisions.

• cranial Nerves: There are ten pairs of cranial nerves originating from the brain.

• Brain: Enclosed in a bony structure called the brain box (cranium). The brain is divided into:

• 1. Forebrain: Includes olfactory lobes, paired cerebral hemispheres, and unpaired diencephalon.

  2. Midbrain: Characterized by a pair of optic lobes.

  3. Hindbrain: Includes cerebellum and medulla oblongata.

• The medulla oblongata passes out through the foramen magnum and continues into the spinal cord, which is enclosed within the vertebral column.

Sense Organs of Frogs:

Frogs possess several types of sense organs, each designed for a specific function:

1. Sense of Touch:

   • Sensory Papillae are responsible for the sense of touch, providing frogs with tactile information.

2. Sense of Taste:

   • Taste Buds are responsible for the frog's sense of taste, typically located in the mouth and throat.

3. Sense of Smell:

   • The Nasal Epithelium helps frogs detect smells, playing a critical role in their olfactory senses.

4. Sense of Vision:

   • Frogs have eyes that are spherical structures situated in the orbit of the skull. Their eyes are simple eyes, meaning they have a single unit without a complex lens system.

5. Sense of Hearing:

   • Frogs lack an external ear; instead, they have a tympanum (external eardrum) which aids in hearing. The tympanum is part of the frog's internal ear, which is not only responsible for hearing but also plays a role in maintaining balance or equilibrium.

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Reproductive System of Frogs:

Frogs have distinct male and female reproductive systems, with the male system being particularly well organized.

Male Reproductive System:

• The male reproductive organs consist of a pair of yellowish ovoid testes (Figure 7.3). These testes are located near the upper part of the kidneys and are attached to the kidneys by a double fold of peritoneum called the mesorchium.

• Vasa efferentia: There are 10-12 vasa efferentia that arise from the testes. These tubes transport sperm from the testes and enter the kidneys on their side.

• These vasa efferentia eventually open into Bidder's duct, which further transports the sperm

Q1. Sponges exhibit which type of body symmetry?

1. Radial

2. Bilateral

3. Asymmetrical

4. Pentaradial

Answer: 3) Asymmetrical

Q2. The level of organization in Porifera is:

1. Protoplasmic

2. Cellular

3. Tissue

4. Organ

Answer: 2) Cellular

Q3. Water enters a sponge’s body through tiny pores called:

1. Oscula

2. Ostia

3. Spicules

4. Choanocytes

Answer: 2) Ostia

4. The cells lining the spongocoel and flagellated to drive water flow are called:

1. Amoebocytes

2. Pinacocytes

3. Choanocytes

4. Porocytes

Answer: 3) Choanocytes

Q5. Digestion in sponges is:

1. Extracellular only

2. Intracellular only

3. Both extracellular and intracellular

4. Absent—they absorb nutrients directly

Answer: 2) Intracellular only

Q6. The sponge skeleton may be composed of:

1. Calcium carbonate spicules or spongin fibers

2. Chitin only

3. Silica only

4. Keratin

Answer: 1) Calcium carbonate spicules or spongin fibers

Q7. Sponges are usually:

1. Dioecious (separate sexes)

2. Hermaphrodite (both gametes in one individual)

3. Parthenogenetic only

4. Asexual only

Answer: 2) Hermaphrodite

Q8. Sponge larvae differ from adults and must undergo metamorphosis; this is an example of:

1. Direct development

2. Indirect development

3. Neoteny

4. Ametabolous life cycle

Answer: 2) Indirect development

Which of the following is a freshwater sponge?

1. Sycon

2. Spongilla

3. Euspongia

4. Scypha

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Answer: 2) Spongilla
Explanation: Spongilla is the classic freshwater sponge genus.

Sycon (also called Scypha) is a typical example of a sponge with which type of canal system?

1. Asconoid

2. Syconoid

3. Leuconoid

4. Rhagon

Answer: 2) Syconoid
Explanation: Sycon has the folded (“syconoid”) body wall to increase choanocyte surface area.

Which genus is the commercial “bath sponge” composed mainly of spongin fibers?

1. Spongilla

2. Sycon

3. Euspongia

4. Grantia

Answer: 3) Euspongia
Explanation: Euspongia (the bath sponge) lacks mineral spicules and is harvested for its spongin skeleton.

Which of these genera has a calcareous spicule skeleton?

1. Spongilla

2. Euspongia

3. Sycon

4. Euplectella

Answer: 3) Sycon
Explanation: Sycon belongs to Calcarea, with calcium carbonate spicules.

Identify the sponge with siliceous spicules (not calcareous):

1. Sycon

2. Spongilla

3. Euspongia

4. Spongilla and Euspongia

Answer: 2) Spongilla
Explanation: Freshwater sponges (Spongilla) have siliceous spicules; Euspongia has no mineral spicules.

Sycon has a syconoid type of canal system which increases the surface area for filtering water.

Reason (R):
In Sycon, the body wall is folded, and choanocytes line the radial canals instead of the spongocoel.

Options:
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: A
Explanation: The folding of the body wall in Sycon creates radial canals lined with choanocytes, increasing the surface area for filtering water, which explains the assertion.

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Tricky MCQ 1

Which of the following statements about Euspongia is incorrect?

1. It has spongin fibers as its skeleton

2. It is a freshwater sponge

3. It is commonly known as the bath sponge

4. It lacks calcareous spicules

Answer: 2
Explanation: Euspongia is a marine sponge, not freshwater.

Assertion-Reasoning Q2

Assertion (A):
Sponges are asymmetrical because they lack true tissues and organs.

Reason (R):
Sponges have a cellular level of organization and do not have muscle or nerve cells.

Options:
A) Both A and R are true, and R explains A
B) Both A and R are true, but R does not explain A
C) A is true but R is false
D) A is false but R is true

Answer: A
Explanation: Sponges lack tissues and organs, leading to their asymmetrical body design.

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What is the function of choanocytes in sponges?

1. Provide structural support

2. Capture and digest food particles from water

3. Help in sexual reproduction

4. Transport oxygen through the body

Answer: 2
Explanation: Choanocytes create water currents and trap food particles for intracellular digestion.

Match the Following

Column A	Column B
1. Sycon	A. Freshwater sponge
2. Spongilla	B. Syconoid canal system
3. Euspongia	C. Bath sponge with spongin
4. Asconoid type sponge	D. Simplest canal system

Answer:
1 - B
2 - A
3 - C
4 - D

Assertion (A):
Cnidarians have a gastrovascular cavity with a single opening that acts as both mouth and anus.

Reason (R):
Digestion in cnidarians is both extracellular and intracellular.

Options:
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: A
Explanation: The gastrovascular cavity has one opening which functions as mouth and anus, and digestion occurs both inside cells and in the cavity.

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Assertion-Reasoning Q2

Assertion (A):
Cnidocytes contain nematocysts which help in defense and prey capture.

Reason (R):
Nematocysts are stinging capsules present in cnidoblasts on the tentacles and body of cnidarians.

Options:
A) Both A and R are true, and R explains A
B) Both A and R are true, but R does not explain A
C) A is true but R is false
D) A is false but R is true

Answer: A
Explanation: The nematocysts inside cnidocytes (cnidoblasts) help cnidarians defend themselves and catch prey.

Which of the following pairs is incorrect?

1. Polyp - Sessile, cylindrical body form

2. Medusa - Free-swimming, umbrella-shaped body form

3. Obelia - Only polyp form throughout life

4. Adamsia - Sea anemone

Answer: 3
Explanation: Obelia shows alternation of generations, having both polyp and medusa forms.

What type of symmetry is exhibited by Coelenterates?

1. Bilateral symmetry

2. Radial symmetry

3. Asymmetry

4. Spiral symmetry

Answer: 2
Explanation: Cnidarians are radially symmetrical animals.

Match the Following

Column A	Column B
1. Physalia	A. Portuguese man-of-war
2. Adamsia	B. Sea anemone
3. Pennatula	C. Sea-pen
4. Meandrina	D. Brain coral

Answer:
1 - A
2 - B
3 - C
4 - D

Assertion (A): Alternation of generations in cnidarians involves both polyp and medusa stages.
Reason (R): Polyps reproduce sexually to form medusae, and medusae reproduce asexually to form polyps.

Options:
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: C
Explanation: Polyps reproduce asexually to form medusae, and medusae reproduce sexually to form polyps. The reason given is reversed.

Assertion (A): Corals secrete a skeleton made of calcium carbonate.
Reason (R): Corals use nematocysts for skeleton formation.

Options:
A) Both A and R are true, and R explains A
B) Both A and R are true, but R does not explain A
C) A is true, but R is false
D) A is false, but R is true

Answer: C
Explanation: Corals secrete calcium carbonate skeletons, but nematocysts are stinging capsules, unrelated to skeleton formation.

Q5:
Which of the following is not true about cnidarians?

1. They have tissue level of organisation

2. They are diploblastic animals

3. Their body is supported by spicules

4. They have radial symmetry

Answer: 3
Explanation: Spicules are found in sponges (Porifera), not cnidarians.

In cnidarians, the process of capturing prey is mainly done by:

1. Choanocytes

2. Cnidocytes

3. Cilia

4. Tentacles without special cells

Answer: 2
Explanation: Cnidocytes with nematocysts capture prey.

Column A	Column B
1. Polyp	A. Hydra
2. Medusa	B. Jellyfish (Aurelia)
3. Nematocyst	C. Stinging capsule
4. Coral skeleton	D. Calcium carbonate

Answer:
1 - A
2 - B
3 - C
4 - D

Assertion (A): Ctenophores have eight rows of ciliated comb plates for locomotion.
Reason (R): The ciliated comb plates help in feeding by capturing prey.

Options:
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: C
Explanation: Ctenophores use ciliated comb plates primarily for locomotion, not feeding.

Assertion (A): Flatworms are acoelomate animals with bilateral symmetry.
Reason (R): They have a coelom but it is reduced in size.

Options:
A) Both A and R are true, and R explains A
B) Both A and R are true, but R does not explain A
C) A is true, but R is false
D) A is false, but R is true

Answer: C
Explanation: Flatworms are acoelomate, meaning they lack a true body cavity (coelom).

Assertion (A): Flatworms possess flame cells for osmoregulation and excretion.
Reason (R): Flame cells help in the movement of water and waste out of the body.

Options:
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: A

Which of the following statements is correct for ctenophores?

1. They have separate sexes and external fertilization

2. They possess acoelomate body structure

3. Digestion is only extracellular

4. They have internal fertilization

Answer: 1

Which phylum do flatworms belong to?

1. Ctenophora

2. Platyhelminthes

3. Porifera

4. Coelenterata

Answer: 2

Which of the following is not a characteristic of Platyhelminthes?

1. Bilateral symmetry

2. Triploblastic and coelomate

3. Dorso-ventrally flattened body

4. Presence of hooks and suckers in parasitic forms

Answer: 2
Explanation: Platyhelminthes are acoelomate, not coelomate.

Column A	Column B
1. Ctenophores	A. Flame cells
2. Platyhelminthes	B. Eight rows of ciliated plates
3. Bioluminescence	C. Light emission
4. Osmoregulation in flatworms	D. Flatworms

Answer:
1 - B
2 - D
3 - C
4 - A

Assertion (A): Aschelminthes are pseudocoelomate animals.
Reason (R): Their body cavity is lined completely by mesoderm.

1. A and R are true, and R correctly explains A

2. 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

Answer: 3) A is true, but R is false
Explanation: “Pseudocoelomate” means the cavity is only partially lined by mesoderm, so R is false.

Assertion (A): Roundworms (e.g., Ascaris) have a complete alimentary canal with a muscular pharynx.
Reason (R): A muscular pharynx helps them absorb nutrients directly through the body surface.

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

Answer: 3) A is true, but R is false
Explanation: The muscular pharynx pumps food along the gut; absorption through the body surface is a separate feature.

Assertion (A): Annelids are metamerically segmented, coelomate animals.
Reason (R): Segmentation allows more efficient locomotion by coordinating circular and longitudinal muscles.

1. A and R true, and R explains A

2. A and R true, but R does not explain A

3. A true, R false

4. A false, R true

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Answer: 1) A and R are true, and R explains A
Explanation: Metamerism plus muscle layers allows peristaltic movement—key to annelid locomotion.

Assertion (A): Earthworms are dioecious.
Reason (R): Each earthworm possesses both male and female reproductive organs.

1. A and R true, R explains A

2. A and R true, R does not explain A

3. A true, R false

4. A false, R true

Answer: 4) A is false, but R is true
Explanation: Earthworms are monoecious (hermaphrodites), so A is false but R correctly describes hermaphroditism

Q5. Which phylum has an excretory system of flame cells?

1. Aschelminthes

2. Annelida

3. Platyhelminthes

4. Cnidaria

Answer: 3) Platyhelminthes
Explanation: Flame cells are characteristic of flatworms (Platyhelminthes), not roundworms or annelids.

In which group is fertilization always internal and sexes are separate?

1. Ctenophora

2. Aschelminthes

3. Porifera

4. Cnidaria

Answer: 2) Aschelminthes
Explanation: Roundworms are dioecious with internal fertilization; most other phyla have more varied modes.

Q7. Which worm would have a well‑developed closed circulatory system and parapodia for swimming?

1. Ascaris

2. Nereis

3. Planaria

4. Spongilla

Answer: 2) Nereis
Explanation: Nereis (Annelida) has parapodia and a closed blood‐vascular system.

Q8. Identify the incorrect statement:
a) Roundworms are pseudocoelomate with a complete gut.
b) Annelids have acoelomate body plans.
c) Nephridia in annelids perform osmoregulation and excretion.
d) Roundworms possess a well‑developed muscular pharynx.

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Answer: b)
Explanation: Annelids are coelomate; only platyhelminths are acoelomate.

Q9. Match each worm with its key feature:

Column A (Worm)	Column B (Feature)
1. Ascaris	A. Pseudocoelomate, dioecious, muscular pharynx
2. Wuchereria	B. Blood‑sucking filarial worm
3. Ancylostoma	C. Hookworm, feeds on host blood
4. Pheretima	D. Monoecious coelomate earthworm
5. Planaria	E. Free‑living flatworm with flame cells

Answer:
1–A, 2–B, 3–C, 4–D, 5–E

Assertion (A): Arthropods possess an exoskeleton made of chitin.
Reason (R): The exoskeleton provides points of attachment for muscles and prevents desiccation.

1. A and R are true, and R explains A

2. 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

Answer: 1
Explanation: Arthropod chitinous exoskeleton does indeed anchor muscles for locomotion and limits water loss.

Assertion (A): Insects (Class Insecta) respire via Malpighian tubules.
Reason (R): Malpighian tubules open into the gut and remove nitrogenous wastes in the form of uric acid.

1. A and R are true, and R explains A

2. 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

Answer: 4
Explanation: Malpighian tubules are excretory structures; insects respire through a tracheal system, not via those tubules.

Q3.
Assertion (A): Molluscs are unsegmented, coelomate animals with a muscular foot.
Reason (R): The foot is derived from fused metameres that no longer appear segmented.

1. A and R are true, and R explains A

2. 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

Answer: 3
Explanation: Molluscs do have a muscular foot, but they are never metamerically segmented—so R is false.

Assertion (A): Limulus (the “king crab”) is called a living fossil.
Reason (R): Its body plan has remained virtually unchanged since the Paleozoic.

1. A and R are true, and R explains A

2. 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

Answer: 1
Explanation: Limulus exhibits ancient chelicerate features with minimal change over ~400 million years, making it a classic “living fossil.”

Q5. Which respiratory organ would you not find in an insect?

1. Tracheae

2. Book lungs

3. Gills

4. All of the above

Answer: 4
Explanation: Insects use a tracheal system only; book lungs are in some arachnids, gills in many aquatic arthropods.

In which molluscan group is the radula absent?

1. Gastropoda (e.g., Pila)

2. Bivalvia (e.g., Pinctada)

3. Cephalopoda (e.g., Sepia)

4. Polyplacophora (e.g., Chaetopleura)

Answer: 2
Explanation: Bivalves lack a radula; they filter‑feed instead.

Q7. Pick the incorrect pairing:

1. Apis – Honey bee

2. Bombyx – Silkworm

3. Laccifer – Lac insect

4. Pheretima – Pseudocoelomate earthworm

Answer: 4
Explanation: Pheretima (earthworm) is a coelomate annelid, not a pseudocoelomate.

✔ Correct/Incorrect Statement

Q8. Identify the incorrect statement:
a) Arthropods are triploblastic and coelomate.
b) Molluscs possess an open circulatory system.
c) Malpighian tubules occur in molluscs for excretion.
d) The mantle secretes the shell in molluscs.

Answer: c
Explanation: Malpighian tubules are characteristic of arthropods (insects etc.), not molluscs.

Answer:
1–A, 2–B, 3–C, 4–D, 5–E

Column A	Column B
1. Anopheles	A. Vector of malaria
2. Locusta	B. Gregarious agricultural pest
3. Limulus	C. Marine chelicerate “living fossil”
4. Pinctada	D. Pearl‑producing bivalve
5. Sepia	E. Cephalopod with internal shell (cuttlebone)

Q1.
Assertion (A): Echinoderms have a water vascular system.
Reason (R): The water vascular system in echinoderms helps in digestion and excretion.

1. A and R are true, and R explains A

2. 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

Answer: 3
Explanation: The water vascular system is used for locomotion, respiration, food capture — not excretion.

Assertion (A): Echinoderms exhibit radial symmetry in adult form.
Reason (R): This is an adaptation to their sessile or slow-moving benthic lifestyle.

1. A and R are true, and R explains A

2. 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

Answer: 1
Explanation: Radial symmetry helps them interact with the environment from all sides.

Q3. Which of the following is incorrect regarding echinoderms?

1. They have an endoskeleton of calcareous ossicles.

2. Adults are bilaterally symmetrical.

3. Excretory system is absent.

4. Development includes a larval stage.

Answer: 2
Explanation: Adults are radially symmetrical; larvae are bilaterally symmetrical.

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Q5. Mouth and anus position in echinoderms is:

1. Both on dorsal side

2. Both on ventral side

3. Mouth on dorsal, anus on ventral

4. Mouth on ventral, anus on dorsal

Answer: 4
Explanation: Mouth is on the lower/ventral side, anus is on the upper/dorsal side.

✔ True/False Type

Q6.
a) All echinoderms are exclusively marine – True
b) They show indirect development – True
c) Water vascular system helps in excretion – False
d) Their larvae are radially symmetrical – False

Q7. Match the echinoderm example to its common name:

Column A	Column B
1. Asterias	A. Sea cucumber
2. Ophiura	B. Star fish
3. Cucumaria	C. Brittle star
4. Antedon	D. Sea lily

Answer:
1–B, 2–C, 3–A, 4–D

Assertion (A): Hemichordates are now placed under Non-Chordata.
Reason (R): They possess a true notochord in the collar region.

1. A and R are true, and R explains A

2. 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

Answer: 3
Explanation: They have a stomochord, not a true notochord — so R is false.

Assertion (A): Hemichordates exhibit indirect development.
Reason (R): Larvae of Hemichordata undergo metamorphosis to form adult.

1. A and R are true, and R explains A

2. 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

Answer: 1

Q3. Which of the following is NOT a characteristic feature of Hemichordates?

1. Stomochord in collar region

2. Dorsally located notochord

3. Body divided into proboscis, collar, and trunk

4. Open circulatory system

Answer: 2
Explanation: They lack a true notochord; the stomochord is a rudimentary structure.

Q4. The excretory organ in Hemichordates is:

1. Malpighian tubules

2. Flame cells

3. Proboscis gland

4. Nephridia

Answer: 3

Which of the following is a worm-like marine animal from Hemichordata?

1. Balanoglossus

2. Chaetopleura

3. Antedon

4. Fasciola

Answer: 1

Q6.
a) Hemichordates are coelomate animals – True
b) Stomochord is equivalent to notochord – False
c) Fertilisation in Hemichordata is external – True
d) Hemichordates have a closed circulatory system – False

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Answer:
1–B, 2–A, 3–B, 4–D

Q7. Match the part of the body with its region in Hemichordates:

Column A	Column B
1. Stomochord	A. Proboscis
2. Proboscis gland	B. Collar
3. Mouth region	C. Trunk
4. Gill slits	D. Collar/Trunk

Q1.
Assertion (A): All chordates have a notochord at some stage of life.
Reason (R): The notochord is replaced by a vertebral column in all chordates.

1. A and R are true, and R explains A

2. 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

Answer: 3
Explanation: Only vertebrates replace notochord with vertebral column. Not all chordates do this.

Assertion (A): Urochordates are marine animals.
Reason (R): They possess notochord throughout life.

1. A and R are true, and R explains A

2. 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

Answer: 3
Explanation: Urochordates have notochord only in larval tail, not throughout life.

Q3. Which of the following structures is not a defining feature of Chordates?

1. Dorsal hollow nerve cord

2. Paired pharyngeal gill slits

3. Ventral solid nerve cord

4. Notochord

Answer: 3

Q4. In Cephalochordata, the notochord:

1. Is absent

2. Is found only in the tail region

3. Extends from head to tail and persists for life

4. Replaced by vertebral column

Answer: 3

Q5. Which of the following is incorrect regarding Vertebrates?

1. Notochord is always retained in adult

2. Have paired fins or limbs

3. Closed circulatory system

4. Ventral muscular heart

Answer: 1

Q6.
a) All vertebrates are chordates – True
b) All chordates are vertebrates – False
c) Urochordates have notochord only in larval tail – True
d) Cephalochordates have gill slits but no nerve cord – False

Q7. Match the group with their respective feature:

Column A	Column B
1. Urochordata	A. Notochord throughout life
2. Cephalochordata	B. Notochord only in larval tail
3. Vertebrata	C. Notochord replaced in adult

Answer:
1–B, 2–A, 3–C

Answer: 1

Q1.
Assertion (A): Cyclostomes are jawless vertebrates.
Reason (R): Their mouth is circular and adapted for sucking.

1. A and R are true, and R explains A

2. 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

Assertion (A): Cyclostomes are marine animals.
Reason (R): They spawn in freshwater and return to marine habitat after metamorphosis.

1. A and R are true, and R explains A

2. 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

v

Answer: 2
Explanation: Both are true but spawning behavior doesn't explain their marine nature.

Q3. Which of the following is not a feature of Cyclostomata?

1. Paired fins

2. Circular sucking mouth

3. Cartilaginous cranium

4. 6-15 pairs of gill slits

Answer: 1

Q4. Cyclostomes show which of the following combinations?

1. Jawed, bony, freshwater

2. Jawless, marine, external fertilisation

3. Jawless, marine, freshwater spawning

4. Jawed, marine, gill-less

v

Answer: 3