Chapter 4: Animal Kingdom – Short Answer Type Questions

CBSE Class 11 Biology Short Answer Questions – Chapter 4: Animal Kingdom (NCERT Based)

Course Details

Course: CBSE Class 11 Biology
Syllabus: NCERT
Unit: Unit I – Diversity in Living World
Chapter: Chapter 4 – Animal Kingdom
CBSE Board Examination: Central Board of Secondary Education – Class 11 (School & Annual Examinations)

CBSE Class 11 Biology Chapter 4 Animal Kingdom – 50 Short Answer Questions with Answers (NCERT)

Section A: Basis of Classification (Q1–Q10)

1. Explain the basis of classification in the Animal Kingdom.
   Animals are classified based on levels of organisation, body symmetry, number of germ layers, nature of body cavity, segmentation, and presence or absence of notochord, reflecting evolutionary advancement.
2. What is meant by levels of organisation in animals?
   Levels of organisation indicate structural complexity, ranging from cellular to organ-system level, helping classify animals according to body organisation.
3. Differentiate between radial and bilateral symmetry.
   Radial symmetry allows division into similar halves around a central axis, while bilateral symmetry divides the body into identical left and right halves.
4. What are diploblastic animals? Give an example.
   Diploblastic animals develop from two germ layers—ectoderm and endoderm. Example: Hydra.
5. Define triploblastic animals.
   Triploblastic animals possess three germ layers—ectoderm, mesoderm, and endoderm—allowing complex organ development.
6. Explain the significance of coelom in animals.
   Coelom provides space for internal organs, allowing their independent movement and better physiological efficiency.
7. What is metameric segmentation?
   It is the repetition of body segments externally and internally, enhancing locomotion and organisation, seen in annelids.
8. What is a notochord?
   A notochord is a flexible rod-like structure that provides support and defines chordates.
9. Why is notochord important in classification?
   Its presence or absence divides animals into chordates and non-chordates.
10. Name any two criteria that indicate evolutionary advancement.
    Development of coelom and organ-system level organisation indicate evolutionary advancement.

Section B: Non-Chordates – Porifera to Ctenophora (Q11–Q20)

11. Describe the general characteristics of Porifera.
    Poriferans are asymmetrical, aquatic animals with cellular organisation, porous bodies, and skeletons made of spicules or spongin.
12. What is the canal system in sponges?
    It is a system of pores and canals that facilitates water circulation for feeding and respiration.
13. State two features of phylum Cnidaria.
    Cnidarians are diploblastic, radially symmetrical animals with tissue-level organisation and stinging cells called cnidocytes.
14. Explain the function of cnidocytes.
    Cnidocytes help in prey capture and defence using toxic substances.
15. Differentiate between polyp and medusa forms.
    Polyps are sessile and cylindrical, while medusae are free-swimming and umbrella-shaped.
16. Write two characteristics of phylum Ctenophora.
    Ctenophores are marine, diploblastic animals with biradial symmetry and locomotion by comb plates.
17. Why are ctenophores called comb jellies?
    They possess eight rows of ciliary comb plates used for movement.
18. Mention one special feature of ctenophores.
    Bioluminescence is a characteristic feature.
19. Give one example each of Porifera and Cnidaria.
    Porifera – Spongilla; Cnidaria – Hydra.
20. Which phylum shows tissue-level organisation first?
    Cnidaria show tissue-level organisation first.

Section C: Platyhelminthes to Annelida (Q21–Q30)

21. Describe the general features of Platyhelminthes.
    They are dorsoventrally flattened, bilaterally symmetrical, triploblastic, and acoelomate animals, mostly parasitic.
22. Why are flatworms called acoelomates?
    They lack a body cavity between body wall and digestive tract.
23. Write two adaptations of parasitic flatworms.
    Presence of hooks and suckers and reduced digestive system.
24. State two characteristics of Aschelminthes.
    They are pseudocoelomate, cylindrical worms with complete digestive systems and separate sexes.
25. Name a disease caused by nematodes.
    Filariasis caused by Wuchereria.
26. Describe the general characteristics of Annelida.
    Annelids are segmented, coelomate animals with closed circulatory systems and organ-system level organisation.
27. Why is Annelida considered evolutionarily advanced?
    Due to true coelom, segmentation, and efficient circulatory system.
28. Give one example of annelid and its habitat.
    Earthworm – terrestrial habitat.
29. Differentiate between acoelomate and coelomate animals.
    Acoelomates lack body cavity, while coelomates possess a true coelom.
30. Which phylum shows metameric segmentation?
    Annelida shows metameric segmentation.

Section D: Arthropoda to Echinodermata (Q31–Q40)

31. Why is Arthropoda the largest phylum?
    Due to adaptability, jointed appendages, and diverse habitats.
32. State two characteristic features of Arthropoda.
    Jointed appendages and chitinous exoskeleton.
33. Describe the circulatory system of arthropods.
    They possess an open circulatory system with haemolymph.
34. Mention one economic importance of arthropods.
    They act as pollinators and vectors of diseases.
35. Describe the body plan of Mollusca.
    Body divided into head, muscular foot, and visceral mass, often protected by a shell.
36. What is the function of mantle in molluscs?
    Mantle secretes the shell and forms mantle cavity.
37. State two features of Echinodermata.
    They are marine, possess water vascular system and spiny skin.
38. Why are echinoderms radially symmetrical as adults?
    Adaptation to a sedentary or slow-moving marine life.
39. Give one example each of Mollusca and Echinodermata.
    Mollusca – Pila; Echinodermata – Starfish.
40. Which phylum has an endoskeleton?
    Echinodermata possess a calcareous endoskeleton.

Section E: Hemichordata & Chordates (Q41–Q50)

41. Why is Hemichordata considered a connecting link?
    They show features of both chordates and non-chordates.
42. Describe the body organisation of hemichordates.
    Body divided into proboscis, collar, and trunk.
43. What are the defining features of chordates?
    Presence of notochord, dorsal hollow nerve cord, pharyngeal gill slits, and post-anal tail.
44. Differentiate between protochordates and vertebrates.
    Protochordates lack vertebral column; vertebrates possess it.
45. What is the significance of vertebral column?
    It provides protection to spinal cord and structural support.
46. Name the jawless vertebrates.
    Cyclostomata.
47. State two features of Pisces.
    Aquatic vertebrates with gills and fins.
48. Why are amphibians called dual-life animals?
    They live both on land and in water.
49. Mention two features of birds (Aves).
    Presence of feathers and wings.
50. State one characteristic feature of mammals.
    Presence of mammary glands.

Exam Relevance

✔ Strictly NCERT-aligned
✔ Ideal for 2–3 mark CBSE Class 11 questions
✔ Covers full Animal Kingdom classification
✔ Useful for school tests and annual examinations