Animal Kingdom Chordates

8 MCQs9-step worked example
Source: NCERT The Living WorldPYQ coverage: NEET 2020, 2021, 2022, 2023, 2024, 2025Official key: NTA-verifiedLast reviewed: May 2026

Lesson

Chordates dominate NEET biology questions on animal kingdom because five classes — Pisces, Amphibia, Reptilia, Aves, and Mammalia — carry dense factual content where a single misplaced feature costs you marks.

The common trap: confusing class-defining characters across adjacent classes. NEET exploits the boundary between Reptilia and Aves (feathers vs scales), between Amphibia and Reptilia (skin glands vs dry skin), and between cartilaginous and bony fish.

Chordate synapomorphies (NCERT Class 11 Biology Chapter 4, page 75): notochord, dorsal hollow nerve cord, pharyngeal gill slits, post-anal tail — present at some life stage in all chordates.

Class-level distinctions NEET tests repeatedly:

  • Cyclostomata — jawless, ectoparasites, circular mouth (Petromyzon, Myxine).
  • Chondrichthyes — cartilaginous endoskeleton, placoid scales, ventral mouth, no operculum, no air bladder. Examples: Scoliodon, Pristis.
  • Osteichthyes — bony endoskeleton, cycloid/ctenoid scales, operculum present, air bladder for buoyancy. Examples: Catla, Hippocampus.
  • Amphibia — moist skin without scales, two-chambered heart in larvae → three-chambered in adults, indirect development (tadpole). Examples: Rana, Salamandra.
  • Reptilia — dry cornified skin, three-chambered heart (crocodiles: four-chambered), internal fertilisation, oviparous mostly. Examples: Chelone, Naja.
  • Aves — feathers, pneumatic bones, four-chambered heart, warm-blooded, oil gland at tail base. Examples: Corvus, Columba.
  • Mammalia — hair/fur, mammary glands, external ear (pinna), seven cervical vertebrae, viviparous (exception: Ornithorhynchus — oviparous). Examples: Macropus, Balaenoptera.

Watch-out: NEET often pairs an organism with a wrong class feature — e.g., "Which has a four-chambered heart?" listing a reptile alongside a bird. Know the exceptions (crocodile's four-chambered heart) or you lose the mark.

Practice MCQs

Select an option to see the explanation. Wrong answers show why your choice was tempting — and name the exact trap it exploits.

MCQ 1Easy RecallPractice

Which of the following is a characteristic feature common to all chordates at some stage of their life cycle?

MCQ 2Easy RecallPractice

Pneumatic bones are a characteristic adaptation found in:

MCQ 3Easy RecallPractice

Which of the following mammals is oviparous?

MCQ 4Direct ApplicationPractice

A fish has a cartilaginous endoskeleton, placoid scales, and lacks an operculum. It belongs to class:

MCQ 5Direct ApplicationPractice

An animal has dry cornified skin, lays eggs on land, and possesses a three-chambered heart with an incomplete septum in the ventricle. This animal most likely belongs to:

MCQ 6Direct ApplicationPractice

Which feature distinguishes Crocodylus from other reptiles regarding heart structure?

MCQ 7CalculationPractice

Consider the following organisms:

MCQ 8CalculationPractice

A student lists the following features for an unknown vertebrate: (1) body covered with feathers, (2) forelimbs modified into wings, (3) three-chambered heart, (4) pneumatic bones. Which statement is correct?

Worked Example

  1. 1

    Given

    An organism has the following features: cartilaginous endoskeleton, ventral mouth, placoid scales, 5–7 gill slits without operculum, and a heterocercal tail.

  2. 2

    Required

    Identify the class and provide one additional expected feature.

  3. 3

    Concept

    Chordate classification relies on matching a diagnostic set of features to the correct class. Each class has a unique combination — no single feature alone is sufficient (e.g., cartilaginous endoskeleton alone doesn't distinguish Cyclostomata from Chondrichthyes; you need additional features).

  4. 4

    Formula/Rule

    Class identification rule: match the COMBINATION of endoskeleton type + scale type + gill covering + mouth position + tail type to the class character table from NCERT.

  5. 5

    Substitution/Matching

    - Cartilaginous endoskeleton → Chondrichthyes or Cyclostomata - Placoid scales → Chondrichthyes (Cyclostomata lack scales) - Ventral mouth → Chondrichthyes (Cyclostomata have circular mouth) - No operculum, 5–7 gill slits → confirms Chondrichthyes - Heterocercal tail → confirms Chondrichthyes

  6. 6

    Working

    Feature-by-feature elimination: - Cyclostomata eliminated at step 2 (scales absent in Cyclostomata) - Osteichthyes eliminated (they have bony endoskeleton + operculum) - All five features converge on Chondrichthyes

  7. 7

    Final answer

    **Class: Chondrichthyes.** Additional expected feature: air bladder absent (buoyancy maintained by continuous swimming and large oily liver).

  8. 8

    Common trap

    Confusing Chondrichthyes with Cyclostomata because both lack an operculum. The discriminator is scales: Chondrichthyes have placoid scales; Cyclostomata have no scales and possess a jawless circular mouth.

  9. 9

    Similar NEET-style question

    "An aquatic vertebrate has a jawless circular sucking mouth, no paired fins, and ectoparasitic habit. Identify the class and one example organism." (Answer: Cyclostomata; example: Petromyzon.) ---

Before solving, remember these

Key Fact

Chordates — five classes

Chordata divided into Pisces (fishes — gills, fins), Amphibia (Rana — moist skin, three-chambered heart), Reptilia (Calotes, Naja — scales, four-chambered with incomplete septum in most), Aves (birds — feathers, four-chambered, endothermic), Mammalia (mammary glands, hair, viviparity in most).

-- NCERT Class 11 Biology, Ch. 4, p. 75

Exam Traps & Common Mistakes

These are the exact patterns that cause wrong answers in NEET. Each trap includes when it triggers and how to avoid it.

Trap

Monera vs Protista confusion

Category: Similar Terms

Both kingdoms include single-celled organisms but Monera is prokaryotic; Protista eukaryotic.

When it triggers

Question lists organisms and asks for kingdom; tempts placing all unicellulars in same kingdom.

How to avoid

Test for nucleus: prokaryote → Monera; eukaryote → Protista regardless of being unicellular.

Trap

Genus and species capitalisation/italicisation reversed

Category: Similar Terms

Binomial nomenclature: genus capitalised, species lowercased; both italicised. Reversing or non-italicising changes the entity.

When it triggers

Question presents a Latin name and asks for the correct typography or which name is genus.

How to avoid

Genus is ALWAYS the first word, capitalised; species is the second, lowercase; both italicised in print.

Past Year Questions

62 questions from NEET 2020, 2021, 2022, 2023, 2024, 2025. Answers verified against NTA official keys.

NEET 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 vertebrate. Reason (R) : The members of subphylum vertebrata possess notochord during the embryonic period, the notochord is replaced by cartilaginous or bony vertebral column in adults. In the light of the above statements, choose the correct answer from the options given below:

1(A) is false but (R) is true
2Both (A) and (R) are true and (R) is the correct explanation of (A)
3Both (A) and (R) are true but (R) is not the correct explanation of (A)
4(A) is true but (R) is false
NTA Answer: Option 2(final)
NEET 2025

Given below are two statements : One is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : A typical unfertilised, angiosperm embryo sac at maturity is 8 nucleate and 7-celled. Reason (R) : The egg apparatus has 2 polar nuclei. In the light of the above statements, choose the correct answer from the options given below :

1A is false but R is true
2Both A and R are true and R is the correct explanation of A
3Both A and R are true but R is NOT the correct explanation of A
4A is true but R is false
NTA Answer: Option 4(final)
NEET 2025

Each of the following characteristics represent a Kingdom proposed by Whittaker. Arrange the following in increasing order of complexity of body organization. A. Multicellular heterotrophs with cell wall made of chitin. B. Heterotrophs with tissue/organ/organ system level of body organization. C. Prokaryotes with cell wall made of polysaccharides and amino acids. D. Eukaryotic autotrophs with tissue/organ level of body organization. E. Eukaryotes with cellular body organization. Choose the correct answer from the options given below :

1C, E, A, B, D
2A, C, E, B, D
3C, E, A, D, B
4A, C, E, D, B
NTA Answer: Option 3(final)
NEET 2025

Which one of the following statements refers to Reductionist Biology?

1Behavioural approach to study and understand living organisms
2Physico-chemical approach to study and understand living organisms
3Physiological approach to study and understand living organisms
4Chemical approach to study and understand living organisms
NTA Answer: Option 2(final)
NEET 2024

Given below are two statements: Statement I : Parenchyma is living but collenchyma is dead tissue. Statement II : Gymnosperms lack xylem vessels but presence of xylem vessels is the characteristic of angiosperms. In the light of the above statements, choose the correct answer from the options given below:

1Both Statement I and Statement II are true
2Both Statement I and Statement II are false
3Statement I is true but Statement II is false
4Statement I is false but Statement II is true
NTA Answer: Option 4(final)
NEET 2023

Given below are two statements : One labelled as Assertion A and the other labelled as Reason R: Assertion A : The first stage of gametophyte in the life cycle of moss is protonema stage. Reason R : Protonema develops directly from spores produced in capsule. In the light of the above statements, choose the most appropriate answer from options given below:

1Both A and R are correct but R is NOT the correct explanation of A
2A is correct but R is not correct
3A is not correct but R is correct
4Both A and R are correct and R is the correct explanation of A
NTA Answer: Option 4(final)
NEET 2023

Given below are two statements : One labelled as Assertion A and the other labelled as Reason R : Assertion A : In gymnosperms the pollen grains are released from the microsporangium and carried by air currents. Reason R : Air currents carry the pollen grains to the mouth of the archegonia where the male gametes are discharged and pollen tube is not formed. In the light of the above statements, choose the correct answer from the options given below :

1Both A and R are true but R is NOT the current explanation of A
2A is true but R is false
3A is false but R is true
4Both A and R are true and R is the correct explanation of A
NTA Answer: Option 2(final)
NEET 2023

Given below are two statements : One is labelled as Assertion A and the other is labelled as Reason R : Assertion A : A flower is defined as modified shoot wherein the shoot apical meristem changes to floral meristem. Reason R : Internode of the shoot gets condensed to produce different floral appendages laterally at successive node instead of leaves. In the light of the above statements, choose the correct answer from the options given below :

1Both A and R are true but R is NOT the correct explanation of A
2A is true but R is false
3A is false but R is true
4Both A and R are true and R is the correct explanation of A
NTA Answer: Option 4(final)
NEET 2023

Given below are two statements: Statement I: In prokaryotes, the positively charged DNA is held with some negatively charged proteins in a region called nucleoid. Statement II: In eukaryotes, the negatively charged DNA is wrapped around the positively charged histone octamer to form nucleosome. In the light of the above statements, choose the correct answer from the options given below:

1Both Statement I and Statement II are false.
2Statement I is correct but Statement II is false.
3Statement I is incorrect but Statement II is true.
4Both Statement I and Statement II are true.
NTA Answer: Option 3(final)
NEET 2023

Match List I with List II with respect to human eye. List I List II A. Fovea I. Visible coloured portion of eye that regulates diameter of pupil. B. Iris II. External layer of eye formed of dense connective tissue. C. Blind spot III. Point of greatest visual acuity or resolution. D. Sclera IV. Point where optic nerve leaves the eyeball and photoreceptor cells are absent. Choose the correct answer from the options given below:

1A-IV, B-III, C-II, D-I
2A-I, B-IV, C-III, D-II
3A-II, B-I, C-III, D-IV
4A-III, B-I, C-IV, D-II
NTA Answer: Option 4(final)
NEET 2023

Match List I with List II. List I List II (Interacting species) (Name of interaction) A. A Leopard and a Lion in a forest/grassland I. Competition B. A Cuckoo laying egg in a Crow’s nest II. Brood parasitism C. Fungi and root of a higher plant in Mycorrhizae III. Mutualism D. A cattle egret and a Cattle in a field IV. Commensalism Choose the correct answer from the options given below.

1A-I, B-II, C-IV, D-III
2A-III, B-IV, C-I, D-II
3A-II, B-III, C-I, D-IV
4A-I, B-II, C-III, D-IV
NTA Answer: Option 4(final)
NEET 2023

The unique mammalian characteristics are:

1hairs, pinna and mammary glands
2hairs, pinna and indirect development
3pinna, monocondylic skull and mammary glands
4hairs, tympanic membrane and mammary glands
NTA Answer: Option 1(final)
NEET 2022

Identify the correct set of statements : (a) The leaflets are modified into pointed hard thorns in Citrus and Bougainvillea (b) Axillary buds form slender and spirally coiled tendrils in cucumber and pumpkin (c) Stem is flattened and fleshy in Opuntia and modified to perform the function of leaves (d) Rhizophora shows vertically upward growing roots that help to get oxygen for respiration (e) Subaerially growing stems in grasses and strawberry help in vegetative propagation Choose the correct answer from the options given below :

1(a), (b), (d) and (e) Only
2(b) and (c) Only
3(a) and (d) Only
4(b), (c), (d) and (e) Only
NTA Answer: Option 4(final)
NEET 2022

Match the plant with the kind of life cycle it exhibits: List-I List-II (a) Spirogyra (i) Dominant diploid sporophyte vascular plant, with highly reduced male or female gametophyte (b) Fern (ii) Dominant haploid free-living gametophyte (c) Funaria (iii) Dominant diploid sporophyte alternating with reduced gametophyte called prothallus (d) Cycas (iv) Dominant haploid leafy gametophyte alternating with partially dependent multicellular sporophyte Choose the correct answer from the options given below :

1(a)-(ii), (b)-(iv), (c)-(i), (d)-(iii)
2(a)-(iv), (b)-(i), (c)-(ii), (d)-(iii)
3(a)-(ii), (b)-(iii), (c)-(iv), (d)-(i)
4(a)-(iii), (b)-(iv), (c)-(i), (d)-(ii)
NTA Answer: Option 3(final)
NEET 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 option given below :

1(A) is not correct but (R) is correct
2Both (A) and (R) are correct and (R) is the correct explanation of (A)
3Both (A) and (R) are correct but (R) is not the correct explanation of (A)
4(A) is correct but (R) is not correct
NTA Answer: Option 2(final)
NEET 2022

In the taxonomic categories which hierarchical arrangement in ascending order is correct in case of animals?

1Kingdom, Order, Phylum, Class, Family, Genus, Species
2Kingdom, Phylum, Class, Order, Family, Genus, Species
3Kingdom, Class, Phylum, Family, Order, Genus, Species
4Kingdom, Order, Class, Phylum, Family, Genus, Species Answer (2*) 178. Given below are two statements : Statement I : Fatty acids and glycerols cannot be absorbed into the blood. Statement II : Specialized lymphatic capillaries called lacteals carry chylomicrons into lymphatic vessels and ultimately
NTA Answer: Option 2(final)
NEET 2021

Gemmae are present in (4) 2, 4-D

1Some Liverworts Answer (4)
2Mosses 125. Which of the following algae produce Carrageen?
3Pteridophytes (1) Blue-green algae
4Some Gymnosperms (2) Green algae
NTA Answer: Option 1(final)
NEET 2021

With regard to insulin choose correct options. (b) Echinoderms are triploblastic and coelomate animals. (a)C-peptide is not present in mature insulin. (c) Round worms have organ-system level of body (b)The insulin produced by rDNA technology has C- organization. peptide. (d) Comb plates present in ctenophores help in (c)The pro-insulin has C-peptide digestion. (d)A-peptide and B-peptide of insulin are (e) Water vascular system is characteristic of interconnected by disulphide bridges. Echinoderms. Choose the correct answer from the option given Choose the correct answer from the options given

1(a) and (d) only (1) (b), (c) and (e) are correct
2(b) and (d) only (2) (c), (d) and (e) are correct
3(a), (b) and (c) are correct (3) (b) and (c) only
4(a), (d) and (e) are correct (4) (a), (c) and (d) only
NTA Answer: Option 1(final)
NEET 2021

Match List - I with List - II (b) 'A' band widens List - I List - II (c) 'I' band reduces in width (a) Adaptive (i) Selection of (d) Myosine hydrolyzes ATP, releasing the ADP and radiation resistant varieties Pi due to excessive use of herbicides (e) Z-lines attached to actins are pulled inwards and pesticides Choose the correct answer from the options given (b) Convergent (ii) Bones of forelimbs beloow evolution in Man and Whale

1(b), (d), (e), (a) only (c) Divergent (iii) Wings of Butterfly evolution and Bird
2(a), (c), (d), (e) only (d) Evolution by (iv) Darwin Finches
3(a), (b), (c), (d) only anthropogenic
4(b), (c), (d), (e) only action
NTA Answer: Option 2(final)
NEET 2020

ÁŸêŸÁ‹Áπà ◊ ‚ ∑§ÊÒŸ ‚Ê ÿÈÇ◊ ∞∑§ ∑§Ê Á‡Ê∑§Ëÿ ‡ÊÒflÊ‹Ê ∑§Ê 91. Which of the following pairs is of unicellular „Ò? algae ?

1Chlorella and Spirulina (1) Ä‹Ê ⁄ U‹Ê •ÊÒ⁄U S¬ÊßL§‹ËŸÊ
2Laminaria and Sargassum (2) ‹ÒÁ◊Ÿ Á⁄UÿÊ •ÊÒ⁄U ‚Ê⁄UªÊ‚◊
3Gelidium and Gracilaria (3) ¡ Á‹Á«Uÿ◊ •ÊÒ⁄U ª˝ÊÁ‚‹ Á⁄UÿÊ
4Anabaena and Volvox (4) ∞ ŸÊ’ËŸÊ •ÊÒ⁄U flÊÚÀflÊÚÄ‚
NTA Answer: Option 1(final)
NEET 2020

Á∑§‚ ÁflÁœ mÊ⁄UÊ ’Ë∑§ÊŸ ⁄UË ∞ flË¡ ∞fl ◊Ò⁄UËŸÊ ⁄ Uê‚ ‚ ÷ «∏ ∑§Ë 94. By which method was a new breed ‘Hisardale’ of sheep formed by using Bikaneri ewes and Marino Ÿß¸ ŸS‹ “Á„‚Ê⁄U« U‹” ÃÒÿÊ⁄U ∑§Ë ªÿË „Ò? rams ?

1•Ã —¬¡˝ ŸŸ (1) Inbreeding
2’Á„—¬˝¡ŸŸ (2) Out crossing
3©à¬Á⁄UfløŸ ¬˝¡ŸŸ (3) Mutational breeding
4‚∑ §⁄UáÊ (4) Cross breeding
NTA Answer: Option 4(final)
NEET 2020

ÿÁŒ ŒÊ ‹ªÊÃÊ⁄U ˇÊÊ⁄U ÿÈÇ◊Ê ∑ § ’Ëø ∑§Ë ŒÍ⁄UË 0.34 nm „Ò •ÊÒ⁄U 106. If the distance between two consecutive base pairs is 0.34 nm and the total number of base pairs of a ∞∑§ S߬ÊÿË ∑§Ê Á‡Ê∑§Ê ∑§Ë DNA ∑§Ë Ám∑È §«U‹Ë ◊ ˇÊÊ⁄U ÿÈÇ◊Ê DNA double helix in a typical mammalian cell is ∑§Ë ∑ȧ‹ ‚ ÅÿÊ 6.6×109 bp „Ò– Ã’ DNA ∑§Ë ‹ê’Ê߸ 6.6×109 bp, then the length of the DNA is „Ê ªË ‹ª÷ª — approximately :

12.7 ◊Ë≈U⁄U (1) 2.7 meters
22.0 meters (2) 2.0 ◊Ë≈U⁄U
32.5 meters (3) 2.5 ◊Ë≈U⁄U
42.2 meters (4) 2.2 ◊Ë≈U⁄U
NTA Answer: Option 4(final)
NEET 2020

ÁŸêŸÁ‹Áπà ◊ ‚ ‚„Ë ÿÈÇ◊ ∑§Ê øÈÁŸ∞ —

1∞Ä‚Ê ãÿÍÁÄ‹ÿ ¡ - «Ë.∞Ÿ.∞. ◊ ÁflÁ‡Êc≈U 133. Choose the correct pair from the following : SÕÊŸÊ ¬⁄U ∑§Ê≈U (1) Exonucleases - Make cuts at specific ‹ªÊÃÊ „Ò positions within DNA
2‹Êߪ ¡ - ŒÊ «UË.∞Ÿ.∞. ∑ § (2) Ligases - Join the two DNA •áÊÈ•Ê ∑§Ê ¡Ê «∏ÃÊ „Ò molecules
3¬ÊÚÁ‹◊⁄ U¡ - «UË.∞Ÿ.∞. ∑§Ê πá«UÊ ◊ ÃÊ «∏ÃÊ „Ò (3) Polymerases - Break the DNA into
4ãÿÍÁÄ‹ÿ ¡ - «UË.∞Ÿ.∞. ∑ § ŒÊ fragments ⁄UîÊÈ∑§Ê ∑§Ê ¬ÎÕ∑§ (4) Nucleases - Separate the two strands ∑§⁄UÃÊ „Ò of DNA
NTA Answer: Option 2(final)

How NEET usually asks this

Recurring question shapes from past papers. Each pattern shows why wrong options look tempting.

Identification, classification, taxonomy questions across kingdoms and major phyla

RecallMedium

Common distractors

plant life cycle ploidy confusion

Double fertilization produces two products; students assign 2n to both zygote and endosperm nucleus, forgetting the two polar nuclei each contribute 1n.

gymnosperm angiosperm feature swap

Both groups produce seeds; students attribute angiosperm features (flowers, fruit) to gymnosperms or deny gymnosperm-exclusive features (naked seeds, cones).

disease causative organism mismatch

Many diseases are associated with look-alike organism classes; students swap bacterial, fungal, protozoan, and viral agents for well-known diseases.

coelomate pseudocoelomate acoelomate confusion

Porifera has a spongocoel water canal; students interpret any internal space as a coelom and classify sponges as pseudocoelomate rather than acoelomate.

chordate nerve cord reversal

Students recall 'dorsal' but forget 'hollow single'; canonical distractor 'mid-dorsal, solid and double' catches the partially-right recall.

fungi classification non criterion

Mode of nutrition is used to define kingdom Fungi overall; students incorrectly extend it as a criterion for classification WITHIN fungi.

assertion reason unchecked reason

In A-R format, a true assertion with a plausible-sounding reason tempts students into selecting option A without independently verifying whether the reason is correct and whether it genuinely explains the assertion.

prokaryote membrane organelle swap

Students learn prokaryotes lack membrane-bound organelles but incorrectly exclude ribosomes (not membrane-bound) from prokaryotes, or assume prokaryotes have some organelles simply because they are complex organisms.

Sources

NCERT refs: Class 11 Biology Chapter 4, p.75

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