Chapter 4 : Animal Kingdom

Class 11 Biology Chapter 4 Animal Kingdom Exercise Questions and Answers :

1. What are the difficulties that you would face in classification of animals, if common fundamental features are not taken into account?

Answer : Without considering common fundamental features, animal classification becomes arbitrary and less informative. The basic fundamental features such as level of organisation, symmetry, cell organisation, coelom, segmentation, notochord, etc., have enabled us to broadly classify the animal kingdom. Besides the fundamental features, there are many other distinctive characters which are specific for each phyla or class. Ignoring these features would lead to a lack of organization, making it difficult to understand relationships between species. Specific distinctions unique to each phylum or class are important for fine-grained classification but should be built upon the foundation of fundamental features to ensure a coherent and accurate system.

2. If you are given a specimen, what are the steps that you would follow to classify it?

Answer : To classify a specimen, follow these simple steps:

Observation: Carefully examine the specimen, noting its physical characteristics, such as size, shape, color, and any distinctive features.

Comparison: Compare the specimen's features to known characteristics of different taxonomic groups, like phyla, classes, or families.

Identification: Use field guides, keys, or taxonomic resources to identify the specimen's likely classification.

Classification: Place the specimen in its appropriate taxonomic group, such as kingdom, phylum, class, order, family, genus, and species.

Record: Document your findings, including where and when the specimen was found, and any other relevant information.

Verification: If necessary, consult experts or reference materials to confirm the classification.

Labeling: Label the specimen with its classification and any other pertinent details for future reference.

3. How useful is the study of the nature of body cavity and coelom in the classification of animals?

Answer : The study of the nature of the body cavity and coelom is crucial in animal classification. It helps categorize animals into coelomates (e.g., annelids, molluscs, arthropods, echinoderms, hemichordates, and chordates), pseudocoelomates (e.g., aschelminthes), and acoelomates (e.g., platyhelminthes). The presence or absence of these cavities, and their lining by mesoderm, provides fundamental criteria for organizing and distinguishing major animal groups, contributing significantly to the classification of animals.

4. Distinguish between intracellular and extracellular digestion?

Answer : The difference between intracellular and extracellular digestion are :

Intracellular Digestion	Extracellular Digestion
Inside cells	Outside cells
Occurs within cells, with enzymes breaking down food particles inside vesicles or vacuoles.	Takes place in the external environment, where enzymes are secreted to break down food, and the digested nutrients are then absorbed.
Simple organisms, like some protozoa.	More complex organisms, including many animals.
Generally less efficient for extracting nutrients from food.	More efficient for extracting nutrients from food.
No waste elimination outside the cell is needed.	Waste elimination is necessary outside the organism's body.
Amoebas utilize intracellular digestion.	Humans and many animals employ extracellular digestion.

5. What is the difference between direct and indirect development?

Answer : The difference between direct and indirect development :

Direct Development	Indirect Development
Resemble miniature adults from birth.	Undergo distinct larval stages, differing from adults.
No metamorphosis occurs.	Metamorphosis is typically a part of the developmental process.
Generally less parental care needed.	Often requires more parental care and protection during vulnerable larval stages.
Generally a shorter developmental period.	Often involves a longer developmental period due to multiple stages.
Less ability to adapt to changing environments.	Enhanced adaptability to diverse environmental conditions during larval stages.
Mammals, most reptiles, and birds exhibit direct development.	Insects, amphibians, and some marine invertebrates showcase indirect development.

6. What are the peculiar features that you find in parasitic platyhelminthes?

Answer :  The peculiar features of parasitic platyhelminthes, as described in the provided paragraph, include:

(a) They have a flattened body shape, which is why they are called flatworms.

(b) Most of them are endoparasites, living inside the bodies of animals, including humans.

(c) These flatworms exhibit bilateral symmetry.

(d) They have three germ layers (triploblastic) and lack a true body cavity (acoelomate).

(e) Parasitic forms have specialized attachment structures like hooks and suckers, which help them cling to their host.

(f) Some flatworms absorb nutrients directly through their body surface, often simplifying or reducing their digestive systems.

(g) These specialized cells assist in osmoregulation (regulating water balance) and excretion.

(h) They often possess both male and female reproductive organs in the same individual (hermaphroditic).

(i) Fertilization occurs internally, within the body of the parasite.

(j) Their development involves multiple larval stages, typically within their host.

(k) Some members, like Planaria, have a high capacity for regeneration, enabling them to regrow lost body parts.

7. What are the reasons that you can think of for the arthropods to constitute the largest group of the animal kingdom?

Answer : Arthropods constitute the largest animal group due to their remarkable diversity. This phylum, including insects, represents over two-thirds of all named Earth species. Their organ-system level of organization, bilateral symmetry, segmented bodies, and chitinous exoskeletons provide adaptability. Jointed appendages, diverse respiratory structures, and open circulatory systems enhance their versatility. Arthropods possess sensory organs, such as antennae and eyes, and excrete waste through malpighian tubules. Most arthropods exhibit dioecious reproduction with internal fertilization, primarily laying eggs. They employ both direct and indirect developmental strategies. Economically significant species like honey bees, silkworms, and ecological roles as vectors and pests further contribute to their prominence. Ancient lineages, exemplified by living fossils like the king crab, highlight their enduring success.

8. 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 characteristic of the group (c) Echinodermata.

This unique system is a hydraulic network of canals and tube feet that echinoderms, such as starfish and sea urchins, use for locomotion, feeding, and respiration.

9. “All vertebrates are chordates but all chordates are not vertebrates”. Justify the statement.

Answer : The statement is justified by the hierarchical classification of organisms. All vertebrates, a subphylum of chordates, possess the fundamental characteristics of chordates at some point in their life cycle. However, chordates also include non-vertebrate subphyla like Urochordata (tunicates) and Cephalochordata (lancelets). These non-vertebrate chordates retain the notochord throughout their life, making them distinct from vertebrates, confirming that all chordates are not vertebrates.

10. How important is the presence of air bladder in Pisces?

Answer : The presence of an air bladder (swim bladder) in fish, also known as Pisces, is essential for buoyancy control, energy conservation, predator avoidance, gas exchange, and habitat adaptation, allowing them to thrive and survive in aquatic environments.

11. What are the modifications that are observed in birds that help them fly?

Answer :  Birds possess a set of remarkable modifications for flight. These include feathers, beaks for handling food in the air, and wings derived from forelimbs. Their hind limbs are adapted for various functions like walking, swimming, or perching. Dry skin, except for an oil gland, reduces weight. A fully ossified endoskeleton with hollow bones decreases mass while maintaining strength. Additional digestive chambers, a four-chambered heart, air sacs for efficient respiration, and internal fertilization further enhance their flying capabilities.

12. Could the number of eggs or young ones produced by an oviparous and viviparous mother be equal? Why?

Answer : The number of eggs or young ones produced by an oviparous and viviparous mother is unlikely to be equal due to fundamental differences in their reproductive strategies:

Oviparous Reproduction:

(i) Oviparous organisms lay eggs externally.

(ii) The development of the embryo occurs outside the mother's body.

(iii) The number of eggs produced can vary, but it is often higher to increase the chances of survival since there is no maternal protection or nourishment during development.

(iv) The survival rate of offspring depends on environmental conditions and predators.

Viviparous Reproduction:

(i) Viviparous organisms give birth to live young ones.

(ii) Embryos develop inside the mother's body and receive nourishment and protection.

(iii) The number of young produced is generally lower, as maternal resources are invested in the growth and development of each embryo.

(iv) The survival rate of offspring is often higher due to maternal care and support.

While it is theoretically possible for the number of eggs produced by an oviparous mother to be similar to the number of live young produced by a viviparous mother, this scenario is rare. The reproductive strategies have evolved to optimize the chances of offspring survival in their respective environments. Oviparous species often produce more eggs to compensate for higher mortality, while viviparous species invest more resources in each offspring, resulting in fewer young .

13. Segmentation in the body is first observed in which of the following:

(a) Platyhelminthes (b) Aschelminthes (c) Annelida (d) Arthropoda

Answer : Segmentation in the body is first observed in the phylum (c) Annelida.

Annelids, such as earthworms and leeches, are characterized by a segmented body, which is a defining feature of this group.

14. Match the following:

(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

Answer :  The matching pairs are :

(a) Operculum ------- (viii) Osteichthyes

(b) Parapodia -------- (v) Annelida

(c) Scales ----------  (iv) Reptilia

(d) Comb plates -------  (i) Ctenophora

(e) Radula ------------  (ii) Mollusca

(f) Hairs -----------  (vii) Mammalia

 (g) Choanocytes -------- (iii) Porifera

(h) Gill slits ----------- (vi) Cyclostomata and Chondrichthyes

15. Prepare a list of some animals that are found parasitic on human beings.

Answer : Some animals that are found parasitic on human beings are :

(i) Liver flukes (Fasciola)   (ii) Wuchereria (Filaria worm)   (iii) Giardia  (iv) Pinworm (Enterobius) (v) Bedbugs (vi) Roundworms (Ascaris)  (vii) Tapeworms (Taenia)  (viii) Hookworms (Ancylostoma)  (ix) Scabies mites  (x) Chiggers