This MCQ module is based on: NCERT Exercises and Solutions: Animal Kingdom
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NCERT Exercises and Solutions: Animal Kingdom
🎓 Class 11
Biology
CBSE
Theory
Ch 4 – Animal Kingdom
⏱ ~8 min
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NCERT Exercises and Solutions: Animal Kingdom
Chapter Summary — Animal Kingdom at a Glance
The animal kingdom (~1 million identified species) is classified using six fundamental features: level of organisation, symmetry, germ layers, coelom, segmentation and presence/absence of notochord. The chart below summarises every phylum (and sub-class) you have studied.
| Phylum | Symmetry / Layers | Coelom & Segmentation | Diagnostic Features | Examples |
|---|---|---|---|---|
| Porifera | Asymmetric; cellular level | — | Ostia, spongocoel, osculum, choanocytes, spicules/spongin | Sycon, Spongilla, Euspongia |
| Coelenterata (Cnidaria) | Radial; diploblastic | Acoelomate | Cnidoblasts; polyp/medusa; gastrovascular cavity | Hydra, Aurelia, Adamsia, Pennatula, Physalia, Meandrina |
| Ctenophora | Radial; diploblastic | Acoelomate | 8 rows of comb plates; bioluminescence | Pleurobrachia, Ctenoplana |
| Platyhelminthes | Bilateral; triploblastic | Acoelomate | Flat body, flame cells, mostly parasitic | Planaria, Fasciola, Taenia |
| Aschelminthes (Nematoda) | Bilateral; triploblastic | Pseudocoelomate | Cylindrical, complete gut, dioecious | Ascaris, Wuchereria, Ancylostoma |
| Annelida | Bilateral; triploblastic | Coelomate; metamerically segmented | Closed circulation, nephridia, parapodia in Nereis | Pheretima, Nereis, Hirudinaria |
| Arthropoda | Bilateral; triploblastic | Coelomate; segmented | Chitinous exoskeleton, jointed appendages, malpighian tubules, open circulation | Apis, Periplaneta, Bombyx, Locusta, Limulus, Anopheles |
| Mollusca | Bilateral; triploblastic | Coelomate; unsegmented | Calcareous shell, mantle, radula, head + foot + visceral hump | Pila, Pinctada, Sepia, Loligo, Octopus, Aplysia |
| Echinodermata | Adult radial / larva bilateral; triploblastic | Coelomate; unsegmented | Water vascular system, calcareous endoskeleton, marine | Asterias, Echinus, Antedon, Cucumaria, Ophiura |
| Hemichordata | Bilateral; triploblastic | Coelomate; unsegmented | Proboscis + collar + trunk; proboscis gland | Balanoglossus, Saccoglossus |
| Chordata | Bilateral; triploblastic; coelomate | Notochord, dorsal hollow nerve cord, paired pharyngeal gill slits, post-anal tail | Subphyla: Urochordata (Ascidia), Cephalochordata (Branchiostoma), Vertebrata | Petromyzon, Scoliodon, Catla, Rana, Naja, Pavo, Homo |
Vertebrate Classes — Quick Recall
| Class | Skin | Heart | Respiration | Body temp | Reproduction | Examples |
|---|---|---|---|---|---|---|
| Cyclostomata | No scales | 2-chambered | 6–15 pairs gill slits | Cold-blooded | Oviparous; ectoparasites | Petromyzon, Myxine |
| Chondrichthyes | Placoid scales | 2-chambered | Gills (no operculum); no air bladder | Cold-blooded | Internal fertilisation; many viviparous | Scoliodon, Pristis, Trygon |
| Osteichthyes | Cycloid/ctenoid | 2-chambered | Gills + operculum + air bladder | Cold-blooded | External fertilisation; oviparous | Labeo, Catla, Hippocampus |
| Amphibia | Moist, no scales | 3-chambered | Gills, lungs, skin; cloaca | Cold-blooded | External fertilisation; oviparous | Rana, Bufo, Hyla, Ichthyophis |
| Reptilia | Dry scales/scutes | 3 (4 in crocs) | Lungs | Cold-blooded | Internal fertilisation; oviparous | Naja, Crocodilus, Chelone |
| Aves | Feathers; beak | 4-chambered | Lungs + air sacs; pneumatic bones | Warm-blooded | Internal; oviparous | Corvus, Pavo, Struthio, Aptenodytes |
| Mammalia | Hair; mammary glands | 4-chambered | Lungs | Warm-blooded | Internal; mostly viviparous | Homo, Equus, Pteropus, Ornithorhynchus |
🎯 Master Identifier — Pick Any Animal Group
Use this single tool to identify any phylum/class. Pick the most distinctive feature you remember:
→ —
Examples: —
📐 Activity 4.5 — Build the Animalia Tree from Scratch
Setup: On a sheet of paper, place 10 phyla in evolutionary order — from simplest to most complex. Write the single key feature that "appears for the first time" at each step.
Predict: Which feature evolved first — true coelom or notochord? Which phylum first introduced segmentation? Which is the largest phylum and why?
- Porifera — Multicellularity, cellular level
- Coelenterata — Tissue level + diploblastic + radial symmetry + cnidoblasts
- Ctenophora — Comb plates + bioluminescence (still diploblastic)
- Platyhelminthes — Bilateral symmetry + triploblastic + organ level
- Aschelminthes — Pseudocoelom + complete gut + organ-system level
- Annelida — True coelom + metameric segmentation + closed circulation
- Arthropoda — Chitinous exoskeleton + jointed appendages (largest phylum)
- Mollusca — Calcareous shell + mantle + radula (2nd largest)
- Echinodermata — Water vascular system + secondary radial symmetry
- Hemichordata + Chordata — Notochord + dorsal hollow nerve cord + gill slits
NCERT Exercises — Worked Solutions
Q1. What are the difficulties that you would face in classification of animals, if common fundamental features are not taken into account?
Without common fundamental features (level of organisation, symmetry, germ layers, coelom, segmentation, notochord), classification would suffer many problems:
- Inconsistency — different scientists would group the same organism differently because they would use different surface features (colour, size, habitat).
- No evolutionary value — superficial features hide ancestry; whales would be classed with fish, dolphins with sharks, bats with birds.
- Endless categories — every minor variation could justify a new group; ~1 million species would need an unmanageable number of categories.
- Difficulty in identification — students and biologists would lack a reliable key; communication across labs/countries would break down.
- Failure to predict — knowing one feature would not predict others (e.g., notochord predicts dorsal nerve cord and gill slits).
Q2. If you are given a specimen, what are the steps that you would follow to classify it?
Step-by-step classification key:
- Level of organisation — cellular (Porifera), tissue (Cnidaria/Ctenophora), organ, or organ-system.
- Body symmetry — asymmetric, radial, or bilateral.
- Germ layers — diploblastic (2 layers) or triploblastic (3 layers).
- Body cavity (coelom) — acoelomate, pseudocoelomate, or coelomate.
- Segmentation — present (Annelida, Arthropoda, Chordata) or absent.
- Notochord — absent (non-chordate) or present (chordate).
- Special diagnostic structure — choanocytes, cnidoblasts, comb plates, flame cells, nephridia, jointed appendages, radula, water vascular system, hair/feathers/mammary glands etc.
- Reproductive features — sexes (separate or hermaphrodite), fertilisation (internal/external), oviparous/viviparous.
Q3. How useful is the study of the nature of body cavity and coelom in the classification of animals?
The presence/absence and lining of the body cavity is one of the most powerful classification criteria — three categories cleanly separate large groups:
- Acoelomate — no body cavity. Mesoderm fills the gap as parenchyma. Example: Platyhelminthes.
- Pseudocoelomate — body cavity present but not entirely lined by mesoderm (only patches). Example: Aschelminthes.
- Coelomate — body cavity completely lined by mesoderm (true coelom). Includes Annelida, Arthropoda, Mollusca, Echinodermata, Hemichordata, Chordata.
Q4. Distinguish between intracellular and extracellular digestion.
| Feature | Intracellular digestion | Extracellular digestion |
|---|---|---|
| Site | Inside cells (food vacuole) | Outside cells (gut/cavity lumen) |
| Food size | Small particles only | Larger food |
| Mode of intake | Phagocytosis | Ingestion through mouth |
| Examples | Sponges (only intracellular); Amoeba | Higher animals — Annelida onwards |
| Both | Coelenterates and Ctenophores show both — extracellular in gastrovascular cavity, then intracellular in cells. | |
Q5. What is the difference between direct and indirect development?
| Direct development | Indirect development |
|---|---|
| Young one resembles the adult | Young one is morphologically different from the adult |
| No larval stage | One or more larval stages present |
| No metamorphosis | Metamorphosis takes place |
| Examples: Reptiles, Birds, Mammals; some nematodes | Examples: Sponges, Coelenterates, Frog (tadpole → frog), Insects (caterpillar → butterfly) |
Q6. What are the peculiar features that you find in parasitic platyhelminthes?
Parasitic flatworms (e.g., Taenia, Fasciola) show several adaptations to parasitism:
- Hooks and suckers for firm attachment to host tissue (e.g., scolex of tapeworm).
- Body covered with thick cuticle resistant to host's digestive juices.
- Loss of digestive system in tapeworms — they directly absorb pre-digested food across the body surface.
- High reproductive capacity — millions of eggs, often hermaphrodite (self-fertilisation possible).
- Complex life cycles with one or more intermediate hosts to ensure transmission.
- Reduced sense organs and locomotor structures (no need inside host).
- Anaerobic respiration — adapted to low-oxygen gut environment.
Q7. What are the reasons that you can think of for the arthropods to constitute the largest group of the animal kingdom?
Arthropods form >65% of all animal species. Reasons:
- Chitinous exoskeleton — protection, support, prevents desiccation.
- Jointed appendages — efficient locomotion (walking, swimming, flying).
- Wings (insects) — escape predators, find mates, disperse to new habitats.
- Open circulation + tracheal system — direct gas delivery to cells, supports tiny bodies.
- Compound eyes + antennae + statocysts — sophisticated sensory equipment.
- Malpighian tubules — water-conserving excretion, vital for terrestrial life.
- Short generation time + high fecundity — rapid evolution & adaptation.
- Diverse mouth parts — chewing, sucking, lapping, piercing — exploit every food source.
- Metamorphosis — larvae and adults occupy different niches → reduces intra-species competition.
Q8. Water vascular system is the characteristic of which group of the following: (a) Porifera (b) Ctenophora (c) Echinodermata (d) Chordata
Answer: (c) Echinodermata. The water vascular system — a network of fluid-filled canals ending in tube feet — is unique to phylum Echinodermata. It powers locomotion, food capture and respiration in starfish, sea urchin, sea cucumber etc.
Q9. "All vertebrates are chordates but all chordates are not vertebrates." Justify the statement.
The phylum Chordata has three subphyla:
- Urochordata (e.g., Ascidia) — notochord present only in larval tail.
- Cephalochordata (e.g., Branchiostoma/Amphioxus) — notochord throughout life, head to tail.
- Vertebrata — notochord present in embryo; replaced by vertebral column in adult.
Q10. How important is the presence of air bladder in Pisces?
The air bladder (or swim bladder) is a gas-filled sac in the body cavity of bony fishes (Osteichthyes). Its functions:
- Buoyancy regulation — by adjusting the gas volume, the fish becomes neutrally buoyant at any depth and does not have to swim continuously to avoid sinking.
- Energy saving — bony fishes can hover, rest, and ambush prey without expending muscular effort.
- Hearing — in some fishes (e.g., catfishes) the air bladder is connected to the inner ear and helps amplify sound.
- Sound production — drumfishes vibrate the bladder to produce mating calls.
Q11. What are the modifications that are observed in birds that help them to fly?
Flight requires reducing weight while increasing power. Birds have evolved many adaptations:
- Feathers — light, strong, generate lift, insulate.
- Forelimbs modified into wings driven by powerful pectoral (breast) muscles attached to a deeply keeled sternum.
- Pneumatic (hollow) bones — long bones contain air cavities → reduced weight without losing strength.
- Air sacs connected to lungs → unidirectional, highly efficient breathing → meets the high oxygen demand of flight.
- Four-chambered heart + warm-bloodedness → high metabolic rate.
- Beak instead of teeth, no urinary bladder, single ovary — all save weight.
- Streamlined body — minimises air resistance.
- Crop and gizzard — efficient digestion to fuel flight.
- Sharp eyesight + cerebellum — vision and balance needed in three-dimensional flight.
Q12. Could the number of eggs or young ones produced by an oviparous and viviparous mother be equal? Why?
No — generally, oviparous animals produce far more eggs than viviparous animals produce young. Reasons:
- External environment risk — oviparous eggs (frogs, fishes, insects, turtles) are laid outside the body. Most are eaten by predators, dry up, or fail to hatch. To compensate, the mother lays thousands or even millions of eggs (e.g., a single Ocean sunfish lays 300 million eggs!).
- Internal protection — viviparous mothers (most mammals) develop the embryo inside the body where it is protected, fed and oxygenated. Survival rate is very high, so only a few young need to be produced (often 1–10).
- Parental care — viviparous animals usually invest heavily in care after birth (lactation, defence). Oviparous parents (most) abandon the eggs.
Q13. Segmentation in the body is first observed in which of the following: (a) Platyhelminthes (b) Aschelminthes (c) Annelida (d) Arthropoda
Answer: (c) Annelida. True metameric segmentation — body divided externally and internally into a series of segments with serial repetition of organs (nephridia, nerves, muscles) — is first observed in Phylum Annelida. Earthworm (Pheretima), Nereis and Hirudinaria are classic examples. Arthropods also show segmentation (often grouped into head, thorax, abdomen) but it appeared in evolution after Annelida.
Q14. Match the following:
| Column A | Column B |
|---|---|
| (a) Operculum | (i) Ctenophora |
| (b) Parapodia | (ii) Mollusca |
| (c) Scales | (iii) Porifera |
| (d) Comb plates | (iv) Reptilia |
| (e) Radula | (v) Annelida |
| (f) Hairs | (vi) Cyclostomata and Chondrichthyes |
| (g) Choanocytes | (vii) Mammalia |
| (h) Gill slits | (viii) Osteichthyes |
Correct matches:
- (a) Operculum → (viii) Osteichthyes
- (b) Parapodia → (v) Annelida (in Nereis)
- (c) Scales → (iv) Reptilia (dry epidermal scales)
- (d) Comb plates → (i) Ctenophora (8 rows of ciliated comb plates)
- (e) Radula → (ii) Mollusca
- (f) Hairs → (vii) Mammalia
- (g) Choanocytes → (iii) Porifera (collar cells)
- (h) Gill slits → (vi) Cyclostomata and Chondrichthyes (note: the question pairs them because in both classes gill slits open separately, without an operculum)
Q15. Prepare a list of some animals that are found parasitic on human beings.
| Parasite | Phylum / Class | Disease / Effect |
|---|---|---|
| Taenia solium (Pork tapeworm) | Platyhelminthes | Taeniasis (intestine), neurocysticercosis (brain) |
| Taenia saginata (Beef tapeworm) | Platyhelminthes | Taeniasis |
| Fasciola hepatica (Liver fluke) | Platyhelminthes | Fascioliasis (liver damage) |
| Schistosoma (Blood fluke) | Platyhelminthes | Schistosomiasis |
| Ascaris lumbricoides (Round worm) | Aschelminthes | Ascariasis (intestinal blockage) |
| Wuchereria bancrofti (Filaria worm) | Aschelminthes | Filariasis / Elephantiasis |
| Ancylostoma duodenale (Hookworm) | Aschelminthes | Hookworm anaemia |
| Enterobius vermicularis (Pinworm) | Aschelminthes | Enterobiasis |
| Hirudinaria (Leech) | Annelida | Blood loss, secondary infection |
| Pediculus humanus (Head/Body louse) | Arthropoda (Insecta) | Pediculosis, vector for typhus |
| Sarcoptes scabiei (Itch mite) | Arthropoda (Arachnida) | Scabies (skin) |
| Cimex (Bed bug) | Arthropoda | Skin irritation, blood loss |
| Anopheles, Culex, Aedes (Mosquitoes) | Arthropoda | Vectors of malaria, filariasis, dengue, Zika |
🎯 Competency-Based Questions
Q1. The first phylum to introduce true coelom is: L1 Remember
Answer: (c) Annelida. Annelids are the first animals in evolutionary sequence to display a true coelom (cavity completely lined by mesoderm) along with metameric segmentation.
Q2. Which feature distinguishes Aves from Mammalia? L2 Understand
Answer: (c). Both Aves and Mammalia share (a), (b), (d). Pneumatic bones and feathers are unique flight adaptations of birds; mammals have hair and mammary glands instead.
Q3. Apply: A small marine animal has a soft body, calcareous shell, foot, and a rasping radula. Which phylum is it? L3 Apply
Calcareous shell + muscular foot + radula = unique combination of Phylum Mollusca. Likely candidate: Pila, Pinctada, or any sea-snail.
Q4. Analyse: Why do crocodiles have a 4-chambered heart while other reptiles have 3? What evolutionary insight does this offer? L4 Analyse
Crocodiles are an exception within Reptilia — their heart has four chambers, fully separating oxygenated and deoxygenated blood. This independent evolution suggests:
- A 4-chambered heart evolved at least twice independently — once on the line leading to birds (which evolved from theropod dinosaurs, related to crocodiles) and once in mammals.
- It supports the modern view that birds and crocodiles share a common ancestor (Archosaurs) — and birds inherited the 4-chambered heart from their reptilian ancestors.
- It shows that classification at the class level can hide such evolutionary nuance — molecular data places crocodiles closer to birds than to other reptiles!
Q5. Create: Suggest three medical or industrial uses for animals belonging to different phyla studied in this chapter. L6 Create
- Porifera (Sponges) — bath sponges (Euspongia); sponge-derived bioactive molecules used in cancer/HIV drugs.
- Annelida (Leeches) — Hirudinaria saliva contains hirudin (anticoagulant); used in microsurgery to maintain blood flow.
- Arthropoda (Honey bee, Silkworm, Lac insect) — honey, beeswax, silk (Bombyx), shellac (Laccifer) — major industries.
- Mollusca (Pearl oyster) — Pinctada for natural and cultured pearls.
- Chordata (Fish, Cattle, Poultry) — food, milk, eggs, leather, vaccines.
🧠 Assertion–Reason Questions
Choose: (A) Both true, R explains A. (B) Both true, R doesn't explain A. (C) A true, R false. (D) A false, R true.
A: Cyclostomes are placed under Vertebrata even though they lack jaws.
R: They possess a cranium and a vertebral column made of cartilage.
Answer: (A). Both true and R explains A. The defining trait of Vertebrata is the presence of a vertebral column (and a brain protected by a cranium); jaws are not a requirement — they evolved later in the gnathostome lineage.
A: Hemichordates were earlier classified under Chordata but are now placed in non-chordata.
R: They lack a true notochord; the structure earlier mistaken for a notochord is actually a buccal diverticulum (stomochord).
Answer: (A). Both true; R explains A. Modern molecular and morphological evidence shows the proboscis "stomochord" is not a true notochord, so hemichordates are classified separately from Chordata.
A: All chordates are vertebrates.
R: Chordata includes Urochordata, Cephalochordata and Vertebrata.
Answer: (D). A is FALSE — Urochordates and Cephalochordates are chordates but NOT vertebrates (they lack a vertebral column). R is TRUE — Chordata indeed has these three subphyla. Conversely, all vertebrates ARE chordates.
Frequently Asked Questions - NCERT Exercises and Solutions: Animal Kingdom
What are the most-asked NCERT exercise questions in Chapter 4 Animal Kingdom?
NCERT Class 11 Biology Chapter 4 Animal Kingdom exercises cover definitions, classification, structure-function relationships, labelled diagrams, and application-based questions. The MyAiSchool exercise set provides full step-by-step solutions for every NCERT question, aligned with the CBSE board exam pattern. Students should master scientific terminology, diagram labelling, and concept comparison tables to score full marks.
How should students approach labelled diagram questions in Animal Kingdom?
For labelled diagram questions in NCERT Class 11 Biology Chapter 4 Animal Kingdom: (1) draw a clean, large, proportional diagram with sharp pencil lines, (2) label each part with horizontal lines on the right or left side, (3) use scientific terminology (Latin/Greek names where applicable), (4) write a 1-2 line description below if asked. The MyAiSchool solutions provide editable reference diagrams aligned with NCERT textbook figures.
What types of CBSE board questions come from Chapter 4?
CBSE Class 11 Biology board questions from Chapter 4 (Animal Kingdom) typically include: (1) 1-mark MCQs on definitions and classification, (2) 2-mark short-answers on structure-function or comparisons, (3) 3-mark labelled-diagram questions, (4) 5-mark long-answer essays combining diagram + description + significance. The MyAiSchool exercise set tags each question by mark weight and Bloom level (L1-L6).
How do I compare two biological concepts in 5-mark questions?
For 5-mark comparison questions in NCERT Class 11 Biology Chapter 4: (1) use a two-column table with feature headings down the left side, (2) compare on at least 5-6 features (structure, function, location, examples, significance), (3) include one labelled diagram if relevant, (4) end with one line on biological significance. The MyAiSchool solutions follow this CBSE-aligned tabular format consistently for full marks.
What are common mistakes in Chapter 4 exercises?
Common mistakes in NCERT Class 11 Biology Chapter 4 (Animal Kingdom) include: (1) confusing similar scientific names or terminology, (2) skipping diagram labels or drawing too small, (3) missing examples in classification questions, (4) writing essay-style answers when a table is expected, (5) forgetting to mention biological significance. The MyAiSchool solutions highlight these traps so students avoid losing marks unnecessarily.
How does the MyAiSchool solution differ from other NCERT solution sets?
MyAiSchool Class 11 Biology Chapter 4 Animal Kingdom solutions use NEP 2024-aligned pedagogy with Bloom Taxonomy tagged questions (L1 Remember to L6 Create), step-by-step working with biological reasoning, fully labelled SVG diagrams, comparison tables, interactive simulations, and Competency-Based Questions (CBQs) for board exam practice. Each solution is verified against NCERT textbook and CBSE marking schemes.
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