EXERCISES

Q1. What are the difficulties that you would face in classification of animals, if common fundamental features are not taken into account?
Answer: If we don’t consider common fundamental features, classifying animals would become confusing and unscientific. It would be hard to group similar animals, compare their body structures, or understand evolutionary relationships. Without these features, classification loses logic and meaning.

Q2. If you are given a specimen, what are the steps that you would follow to classify it?
Answer: To classify a specimen, I would first observe its level of organisation (cellular, tissue, or organ system), then check its symmetry (asymmetrical, radial, or bilateral) and germ layers (diploblastic or triploblastic). Next, I would determine the type of body cavity (acoelomate, pseudocoelomate, or coelomate) and look for the presence of a notochord. Finally, I would identify any special features like segmentation, jointed appendages, or cnidoblasts to place it in the correct group.

Q3. How useful is the study of the nature of body cavity and coelom in the classification of animals?
Answer: The body cavity or coelom helps in grouping animals into logical categories. For example, animals without a cavity are acoelomates (flatworms), those with a false cavity are pseudocoelomates (roundworms), and those with a true cavity are coelomates (annelids, molluscs, etc.). This makes classification scientific and clear.

Q4. Distinguish between intracellular and extracellular digestion.
Answer: Intracellular digestion happens inside cells, like in sponges, where food is digested in food vacuoles. Whereas, extracellular digestion happens outside cells, in a cavity such as a stomach or alimentary canal, like in higher animals.

Q5. What is the difference between direct and indirect development?
Answer: In direct development, the young one looks like a small adult (no larval stage), e.g., reptiles and mammals. Whereas, in indirect development, a larval stage appears that looks different from the adult, e.g., frogs and butterflies.

Q6. What are the peculiar features that you find in parasitic platyhelminthes?
Answer: Parasitic flatworms have special features to survive in their hosts. They use hooks and suckers to attach, absorb food through their body surface, and have flame cells for excretion and water balance.

Q7. What are the reasons that you can think of for the arthropods to constitute the largest group of the animal kingdom?
Answer: Arthropods are the largest group because they are highly adaptable. They have a chitinous exoskeleton for protection, jointed legs for movement, segmented bodies for specialisation, and advanced sense organs like compound eyes  and all helping them survive in every habitat.

Q8. Water vascular system is the characteristic of which group of the following: (a) Porifera (b) Ctenophora (c) Echinodermata (d) Chordata
Answer: The water vascular system is a unique feature of Echinodermata. It helps in movement, food transport, and respiration.

Q9. “All vertebrates are chordates but all chordates are not vertebrates”. Justify the statement.
Answer: All vertebrates are chordates because they have a notochord at some stage. But not all chordates are vertebrates. Some, like Urochordates and Cephalochordates, never develop a vertebral column. Hence, every vertebrate is a chordate, but not every chordate is a vertebrate.

Q10. How important is the presence of air bladder in Pisces?
Answer: The air bladder in bony fishes is like a “float”. It helps them control buoyancy and stay at different water depths without much effort. Cartilaginous fishes don’t have this, so they must keep swimming to avoid sinking.

Q11. What are the modifications that are observed in birds that help them fly?
Answer: Birds are built for flight! Their forelimbs become wings, bones are hollow and light, feathers reduce drag, and air sacs help in efficient breathing. All these make flying easy and energy-efficient.

Q12. Could the number of eggs or young ones produced by an oviparous and viviparous mother be equal? Why?
Answer: Usually no, because oviparous animals lay many eggs with little care, while viviparous animals produce fewer young but protect them well inside the mother’s body. Hence, viviparous animals have fewer but safer offspring.

Q13. Segmentation in the body is first observed in which of the following: (a) Platyhelminthes (b) Aschelminthes (c) Annelida (d) Arthropoda
Answer: Segmentation first appears in Annelida, like in the earthworm, where the body is divided into many repeated segments.

Q14. Match the following:
Answer:
(a) Operculum → Osteichthyes (Bony fishes have gills covered by an operculum)
(b) Parapodia → Annelida (Aquatic annelids like Nereis use parapodia for swimming)
(c) Scales → Reptilia (Body covered by epidermal scales or scutes)
(d) Comb plates → Ctenophora (Used for locomotion)
(e) Radula → Mollusca (Rasping organ for feeding)
(f) Hairs → Mammalia (Skin with hair)
(g) Choanocytes → Porifera (Collar cells for water circulation)
(h) Gill slits → Cyclostomata and Chondrichthyes (Used for respiration)

Q15. Prepare a list of some animals that are found parasitic on human beings.
Answer: Common parasites on humans include:

1. Platyhelminthes: Taenia (tapeworm), Fasciola (liver fluke)
2. Aschelminthes: Ascaris (roundworm), Wuchereria (filaria worm), Ancylostoma (hookworm)
3. Annelida: Hirudinaria (leech)