Animal Kingdom NCERT Solutions

Kingdom Animalia is the most important kingdom in this chapter. Despite disparities in form and structure, there are essential characteristics that allow us to easily categorise them. The phyla of Porifera, Coelenterata (Cnidaria), Ctenophora, Platyhelminthes, Aschelminthes, Annelida, Arthropoda, Mollusca, Echinodermata, Hemichordata, and Chordata are discussed. Animal survival strategies, physiology, environment, and anatomy are all thoroughly discussed. This chapter brings Unit 1: Diversity in Living Organisms to a close. It is worth 14% of the NEET test and 7 marks in the final exam.

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

Solution

Animals are classified based on common features such as the arrangement of cells, body symmetry, nature of coelom, patterns of digestive, circulatory or reproductive systems. Without these common features it is very difficult to deal with every living thing separately, also without common features it is impossible to include new species discovered daily. In order to study the diversity in animals, classification has to be based on the common basic features.

Some other difficulties are:

Tracing of interdependence amongst various animals will become difficult
Difficulty in developing new species of animals

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

Solution:

Following are the steps to be taken to classify a specimen:

Classify level of organization: Classify the arrangement of cells in cellular and tissue level organization.
Symmetry: Classify the organism as radial or bilateral symmetry.
Classify Diploblastic or triploblastic organization
Presence or absence of body cavity
Type of coelom development
Classify segmentation
Differentiate the presence or absence of notochord.

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

Solution:

The coelom is the body cavity or fluid filled space lined by the mesoderm, and animals possessing coelom are called coelomates. In some animals, the body cavity is not lined by mesoderm; instead, the mesoderm is present as scattered pouches in between the ectoderm and endoderm. Such a body cavity is called pseudocoelom and the animals possessing them are called pseudocoelomates, example – Aschelminthes. In some animals body cavity is absent, they are referred to as acoelomates, example – Platyhelminthes.

Classification of body cavity and coelom are important to decide the complexity of an organism at organ level.

4. Distinguish between intracellular and extracellular digestion?

Solution:

Intracellular digestion

Extracellular digestion

Occurs within cells

Occurs within cavity of the ailmentry canal, outside the cell

It occurs in lower organisms

Occurs in multicellular organisms

Enzymes associated are very few

Large number of digestive glands and enzymes are required

It is less efficient with no regional differentiation

Highly efficient with regional differentiation

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

Solution:

Direct development

Indirect development

In direct development, the embryo develops into a well-grown individual without involving in a larval stage.

It involves a sexually immature larval stage

Metamorphosis is absent

Metamorphosis is present

Occurs in fish, reptile birds and mammals

Occurs in in vertebrate amphibians

Ex: Hydra, earthworm

Ex: Frog, butterfly

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

Solution:

Peculiar features found in parasitic Platyhelminthes are as follows:

Free-living parasitic forms
Body organization observed is of tissue organ grade
Mostly hermaphrodites
Three-layered body wall – epidermis (outermost covering) often ciliated and covered by cuticle.
Digestive tract is incomplete or absent
Presence of well-defined excretory structures such as flame cells
Presence of anti-toxins and a thick tegument which is resistant to the digestive enzymes of host
Anaerobic respiration. No special respiratory structure observed
Anterior body part contains suckers, hooks, eye spots and auricles for attachment to the host
Highly developed reproductive system of parasitic forms

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

Solution:

Reasons for arthropods constituting the largest group of the animal kingdom are as follows

They have jointed legs which allow them to be motile, and perform many other functions because of these jointed appendages
Hard skeleton made of chitin protect their body
The hard skeleton also reduces the water loss from the body.
Exhibit distinct system for locomotion, respiration and reproduction
Capability to survive in diverse conditions and varied habitats
In comparison to other phyla, they tend to develop early
Better developed sense organs and nervous system
Some insects exhibit pheromones which enable communication

8. Water vascular system is the characteristic of which group of the following:

(a) Porifera (b) Ctenophora (c) Echinodermata (d) Chordata

Solution:

The answer is (c) Echinodermata

It is their characteristic feature. The perforate plate known as madreporite in them, allow water to percolate into their systems.

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

Solution

Presence of notochord and paired pharyngeal gill slits are the characteristic feature of phylum chordate. But, in subphylum Vertebrata notochord present in the embryo gets replaced by bony vertebral columns in adults. Hence it is said, “All vertebrates are chordates, but all chordates are not vertebrates.”

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

Solution:

Air bladder in Pisces regulates Buoyancy which prevents fishes from sinking.

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

Solution:

Modifications that are observed in birds that help them fly are as follows:

Presence of feathers
Forelimbs are modified into wings, assisting them to take a flight
Hind limbs have scales
They have pneumatic or hollow bones which make the skeleton lightweight
Absence of urinary bladder, causes the net body weight to be reduced, facilitating them to fly
Their streamlined body offers lesser resistance enabling a smooth flight furthermore

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

Solution:

No, the number of eggs or young ones produced by an oviparous and viviparous mother are not equal, the number of eggs produced by oviparous mothers is more comparatively because in oviparous animals, fertilization talks place outside the uterus whereas in viviparous animals’ development takes place inside the uterus which makes successful incubation of young animals lesser.

When eggs are present outside, there is a risk of getting eaten by predators due to their immobility. Therefore, in order to sustain the progeny, there is a requirement for more of eggs.

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

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

Solution:

The answer is (c) Annelida

14. Match the following:

Column I

Column II

(a) Operculum

(i) Ctenophora

(b) Parapodia

(ii) Mollusca

(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

Solution:

Column I

Column II

(a) Operculum

(viii) Osteichthyes

(b) Parapodia

(v) Annelida

(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.

Solution:

Some animals that are found parasitic in humans are as follows:

i. Taenia (Tapeworm)

ii. Ascaris (Roundworm)

iii. Ancylostoma (Hookworm)

iv. Enterobius (Pinworm)

v. Wuchereria (Filarial worm)