Q.Give an example of the following
a. Round worm
b. Fish possessing poison sting
c. A limbless reptile/amphibian
d. An oviparous mammal
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🔒 Start your 14-day free trial to unlock the full solution →Concept understanding — Animal Classification
Imagine walking into a vast library with more than a million books and no shelves, no catalogue, and no order at all. Finding anything, or even understanding what the collection contains, would be hopeless. The animal kingdom presents the same challenge: biologists have already described more than a million animal species. On that scale, a systematic way of grouping animals is not a mere convenience but a necessity.
Animal classification is the orderly grouping of animals so we can make sense of their enormous variety. It lets us do three things: make sense of the sheer diversity, study a few representative types instead of every single species, and give each newly discovered animal a definite, systematic position alongside its relatives. Crucially, the grouping is not arbitrary. Although animals differ enormously in outward shape and form, they share certain deep, fundamental features, and classification is built on these shared features rather than on superficial appearances.
The fundamental characters used as the basis of classification are:
- The level of organisation of the cells (cellular, tissue, organ, or organ-system).
- The body symmetry — whether, and in how many planes, the body divides into matching halves (asymmetry, radial, or bilateral).
- The number of germ layers in the embryo (diploblastic or triploblastic).
- The nature of the coelom, or body cavity — absent, false, or a true mesoderm-lined cavity (acoelomate, pseudocoelomate, or coelomate).
- The presence of segmentation of the body.
- The presence or absence of a notochord (chordate or non-chordate).
The patterns of the digestive, circulatory, and reproductive systems are compared as well. …
a. Round worm — Ascaris.
b. Fish possessing poison sting — Trygon (sting ray).
c. A limbless amphibian — Ichthyophis. …
Ascaris for a round worm, Trygon for a fish with a poison sting, Ichthyophis for a limbless amphibian, and Ornithorhynchus for an oviparous mammal are the specific examples named for each condition.
Each of these categories is illustrated by a named example within the classification scheme.
- a. Round worm: Ascaris is the standard roundworm example from phylum Aschelminthes, a phylum whose members appear circular in cross-section.
- b. Fish possessing a poison sting: among the cartilaginous fishes (Chondrichthyes), Trygon, the sting ray, is specifically noted for carrying a poison sting. …
Method: Odd-one-out / exception-hunting within each category
Instead of recalling a typical example for each category directly, deliberately search for the UNUSUAL or EXCEPTIONAL member of each group, since three of these four blanks are specifically asking for an exception rather than a typical case.
a. Round worm — this blank is NOT asking for an exception, just a typical representative. The standard, most commonly cited roundworm (Aschelminthes) throughout the chapter is Ascaris — no exception-hunting needed here, just the default example.
b. Fish possessing a poison sting — this IS an exception-hunting blank, since most fish do not sting. Scanning the cartilaginous fishes (Chondrichthyes) specifically for an unusual defensive/offensive structure surfaces Trygon, the sting ray, explicitly noted for carrying a poison sting — an exception among fishes generally.
c. A limbless amphibian — this IS an exception-hunting blank, since the typical image of an amphibian (frog, toad) has four limbs. Searching specifically for the atypical, limbless amphibian body form surfaces Ichthyophis, explicitly named as a limbless exception within the class. …
- CBSE 2026Set ANNUAL1 markMCQQ.Match the following: List I -(a) Exocoetus,(b) Pterophyllum,(c) Betta,(d) Labeo; List II -(i) Rohu,(ii) Fighting fish,(iii) flying fish,(iv) Angel fish(a) a) (a)-(i), (b)-(ii), (c)-(iii), (d)-(iv)(b) b) (a)-(iv), (b)-(iii), (c)-(ii), (d)-(i)(c) c) (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i)(d) d) (a)-(iii), (b)-(iii), (c)-(ii), (d)-(i)
›Reveal solutionSolution
[!TLDR]
c) (a)-(iii), (b)-(iv), (c)-(ii), (d)-(i)
Why
Exocoetus = flying fish, Pterophyllum = Angel fish, Betta = Fighting fish, Labeo …
- CBSE 2025Set ANNUAL1 markMCQQ.Select the incorrect statements.(a) In ctenophores, locomotion is mediated by comb plates.(b) In Prawn excretion of waste materials occurs through malpighian tubules.(c) In Fasciola, flame cells take part in excretion.(d) Earthworms are hermaphrodites and yet cross fertilization takes place among them.
›Reveal solutionSolution
Statement (b) is incorrect because prawns excrete through green (antennal) glands, not malpighian tubules — malpighian tubules are the excretory organs of insects, a different class of arthropods.
Checking each option:
- (a) is a correct statement: ctenophores (comb jellies) move using rows of ciliated comb plates on their body surface — this is true (locomotion by comb plates/cilia).
- (b) is the incorrect statement: prawns are crustaceans, and crustacean excretion occurs through green glands (antennal glands) located at the base of the antennae, not malpighian tubules. Malpighian tubules are specific to insects (a different arthropod class) for excreting nitrogenous waste as uric acid.
- (c) is a correct statement: in Fasciola (liver fluke, a flatworm) and other platyhelminthes, flame cells (protonephridia) perform osmoregulation/excretion. …
- CBSE 2024Set ANNUAL1 markMCQQ.Match the following and choose the correct option. Column A: 1) Porifera 2) Annelida 3) Arthropoda 4) Mollusca Column B: A) Metameric segmentation B) Body covered with calcareous shell and mantle C) Jointed appendages with claws D) Body perforated by pores called ostia(a) 1(D), 2(A), 3(C), 4(B)(b) 1(B), 2(D), 3(A), 4(C)(c) 1(D), 2(C), 3(A), 4(B)(d) 1(B), 2(C), 3(D), 4(A)
›Reveal solutionSolution
Each phylum's defining feature: Porifera = pores (ostia), Annelida = segmentation, Arthropoda = jointed appendages, Mollusca = shell + mantle — giving the match 1D, 2A, 3C, 4B.
Matching each animal phylum to its hallmark feature:
- Porifera (sponges) — the body is perforated by numerous minute pores called ostia, through which water enters the spongocoel; hence D) Body perforated by pores called ostia.
- Annelida (segmented worms) — the body shows true metameric segmentation (repetition of similar segments/metameres along the body length); hence A) Metameric segmentation. …
- CBSE 2024Set ANNUAL1 markMCQQ.Cellular level of organisation is seen in(a)(a) Porifera(b)(b) Coelenterata(c)(c) Annelida(d)(d) Mollusca
›Reveal solutionSolution
[!TLDR]
(a) Porifera
Why
In Porifera (sponges), cells are loosely arranged around a water canal system and do not form true tissues, representing the cellular level of organisation …
- CBSE 2023Set ANNUAL1 markMCQQ.Match the column. Item: Flame cell(a) Stigma(b) Cell division(c) Platyhelminthes(d) Cochlea(e) Earthworm(f) Lactation(g) Glycolysis
›Reveal solutionSolution
Flame cells are the excretory cells characteristic of flatworms (phylum Platyhelminthes), so Flame cell matches with Platyhelminthes.
Flame cells (also called protonephridia or solenocytes) are the primitive excretory structures found in organisms like Planaria (a free-living flatworm). Each flame cell has a tuft of cilia inside a hollow bulb that beats constantly, resembling a flickering flame, and creates a current that draws in fluid waste and drives it out throu …
- CBSE 2023Set ANNUAL1 markMCQQ.Match the column. Item: Typhlosole(a) Stigma(b) Cell division(c) Platyhelminthes(d) Cochlea(e) Earthworm(f) Lactation(g) Glycolysis
›Reveal solutionSolution
Typhlosole is a dorsal, longitudinal fold projecting into the intestine that increases the surface area for digestion and absorption, a characteristic feature of the earthworm's alimentary canal.
In the earthworm (Pheretima/Lumbricus), the intestine (from about the 26th/27th segment onward) develops a prominent, ridge-like infolding of its dorsal wall projecting into the intestinal lumen — this is the typhlosole. By increasing the internal absorptive surface area without having to increase overall body/int …
- CBSE 2019Set ANNUAL1 markQ.Give the scientific name of cockroach.
›Reveal solutionSolution
The common cockroach studied in NCERT Biology is scientifically named Periplaneta americana, following the binomial nomenclature system (Genus + species).
In binomial nomenclature, every organism is given a two-part Latinised name: the first part is the Genus (capitalised), and the second is the species (lowercase), both italicised or underlined when handwritten. The cockroach commonly used as a representative …
- CBSE 2018Set ZOOLOGY1 markQ.Give the scientific name of Prawn.
›Reveal solutionSolution
The scientific (genus) name of prawn is Penaeus (e.g., Penaeus monodon, the giant tiger prawn).
Prawn is a crustacean belonging to phylum Arthropoda, class Crustacea, order Decapoda. It is commonly assigned to the genus Penaeus. A commonly cited full scientific (binomial) name for a widely farmed/consumed species is Penaeus monodon (the giant tiger prawn); other Penaeus s …
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