NCERT Solutions for Class 11 Biology Chapter 4 – Animal Kingdom

NCERT Solutions for Class 11 Biology Chapter 4 – the Animal Kingdom is a highly suggested material to be read before giving your examination. These NCERT Solutions are crafted in a simple language, covering all the essential facts with numerous examples. We have answered all the 15 questions of the chapter. 

The chapter Animal Kingdom of class 11 biology textbook meticulously presents the classification of the Kingdom Animalia. Based on the common fundamental features, it categorises various animals into phyla. The chapter of NCERT Solutions for Class 11 also presents a detailed account of each phylum with plentiful examples. Toward the end, a comprehensive chart of the salient features of different phyla is given. 

Important Topics for NCERT Solutions for Class 11 Biology Chapter 4 – The Animal Kingdom

Levels of Organisation: The organisms in the animal kingdom are multicellular. Their cells are arranged in different patterns.

  • Cellular level- cells are arranged as loose cell aggregates. E.g. sponges.
  • Tissue level- cells are arranged into tissues
  • Organ level- tissues are grouped to form organs.
  • Organ system- organs associated to form functional systems connected with a particular function.


Where any plane is passed through the central axis of the body and the body is divided into two identical halves, it is referred to as radial symmetry. E.g. Coelenterates. Whereas in bilateral symmetry, the body can be divided into identical left and right halves in only one plane. E.g. annelids.

Diploblastic and Triploblastic Organisation

In Diploblastic, the cells are arranged into two embryonic layers. The outer layer is ectoderm and the inner layer is the endoderm. In Triploblastic animals, the cells are arranged into three layers- the ectoderm, mesoderm, and endoderm.


It is the cavity in the body which is lined by mesoderm. Annelids, molluscs, etc. are the animals having coelom and are known as coelomates. In some animals the body cavity in mesoderm is present in scattered pouches between the ectoderm and the endoderm, such a cavity is called ass pseudocoelom and the animals are called pseudocoelomates. Where the body cavity in some animals is absent, these animals are called acoelomates.


Bodies of some animals are divided into segments and some of their organs are serially repeated. Like in the earthworm, its body has metameric segmentation.


In some animals during the process of embryonic development, on the dorsal side, some rod-like structure called notochord develops. So, the animals possessing the notochord are known as chordates. And those animals which do not possess the notochord are called the non-chordates. 

Classification of Animals

The major classification of the kingdom Animalia is as follows:

  1. Phylum- Porifera

The animals under this category are usually marine and asymmetrical. They have a cellular level of organisation and are multicellular. Intracellular digestion takes place and the body is supported by a skeleton made up of spicules or spongin fibres. They are hermaphrodite. E.g. sponges.

  1. Phylum- Coelenterata (Cnidaria) 

They are radially symmetrical and aquatic. They are generally marine, sessile or free-swimming. Cnidoblasts or cnidocytes are present on the tentacles and the bodies of these animals. Hypostome i.e. Central gastrovascular cavity is present. Digestion can be extracellular and intracellular. Polyp and medusa are two body forms of it. E.g. Physalia, pennatula, etc.

III. Phylum- Ctenophora

They are marine, radially symmetrical, diploblastic and have tissue-level organisation. They have comb plates and have both extracellular and intracellular digestion. Fertilisation is external. They are generally called as sea walnuts or comb jellies. E.g. Pleurobrachia.

  1. Phylum- Platyhelminthes

They are endoparasites in the body of animals including humans. They have flat bodies and are called flatworms. They are bilaterally symmetrical, triploblastic and are acoelomate. They possess an organ level organisation and have flame cells. Internal fertilisation occurs and the development is various larval stages. E.g. Taenia.

  1. Phylum- Aschelminthes

They are the roundworms having a circular body in cross-section. Their bodies are organ system level organised. They can live freely or can be in parasitic form. They are pseudocoelomate animals having triploblastic and are bilaterally symmetric. The muscular pharynx completes the alimentary canal. They are dioecious and the fertilisation is internal. E.g. Ascaris.

  1. Phylum- Annelida

These animals have organ system level organisation and they can be aquatic or terrestrial, free-living or parasitic. They are bilaterally symmetrical, triploblastic, metamerically segmented and coelomate. The surface of the body has segments or metameres. They have a closed circulatory system and have nephridia. E.g. Nereis.

VII. Phylum- Arthropoda

This phylum is the largest and it includes insects. Organ system-level organisation is present; they are bilaterally symmetrical, triploblastic, segmented, and coelomate. Their body has a chitinous exoskeleton, head, thorax, and abdomen. They have an open circulatory system, jointed appendages and malpighian tubules for excretion.

VIII. Phylum- Mollusca

This phylum is the second largest. Their bodies are covered by a calcareous shell, and it is unsegmented with a head, muscular foot, and visceral hump. Their mouth contains radula and mostly they are dioecious and oviparous.

  1. Phylum- Echinodermata

They possess the endoskeleton of calcareous. They are triploblastic, coelomate. They have a water vascular system. The excretory system is absent. E.g. Asterias.

  1. Phylum- Hemichordata

This phylum has worm-like marine animals and is bilaterally symmetrical, triploblastic, and coelomate. The body contains anterior proboscis, a collar, and a trunk. Proboscis glands for excretion are present. Fertilisation is external.

  1. Phylum- Chordata

They have a notochord, dorsal, hollow nerve cord and paired pharyngeal gill slits. They have a post-anal tail and are symmetrical and triploblastic. This phylum is further divided into 3 subphyla: Urochordata or Tunicata, Cephalochordata, and Vertebrata.

The subphylum Vertebrata is further divided into: 

  1. Class- Cyclostomata: They are the ectoparasites on fish. They have a long body with 6-15 pairs of gill slits. They have cartilaginous cranium and vertebral columns.
  2. Class- Chondrichthyes: They have a streamlined body with a cartilaginous endoskeleton. The notochord is persistent. Gills slits of them are separate and have no operculum. Their skin has minute placoid scales. They can have electric organs or poison sting. They are poikilothermic.

iii. Class- Osteichthyes: They have a bony endoskeleton, with a terminal mouth. Four pairs of gills covered by operculum are present. For buoyancy, air bladder is there. E.g. Exocoetus.  

  1. Class- Amphibia: Most have two pairs of limbs, a head and a trunk. Ear in the form of the tympanum is present. Cloaca is also present. The heart is three-chambered. E.g. Rana.
  2. Class- Reptilia: Their bodies are covered by dry and cornified skin, epidermal scales or scutes. Ear in the form of the tympanum is present. They have creeping or crawling as a mode of locomotion. E.g. Chelone.
  1. Class- Aves: Aves (birds) have feathers, beak and the forelimbs modified into wings. Their bone is hollow with an air cavity and is homoiothermous.

vii. Class- Mammalia: They have mammary glands, and skin is covered by hair. Pinnae (external ear) are present. They are homeothermic.

Exercises Discussion of NCERT Solutions for Chapter 4 – The Animal Kingdom

  • The initial questions deal with the basic classification of the animal kingdom. 
  • Some questions are based on the features of various kingdom classifications. 
  • A few comparative questions based on phylum are also given.
  • There are very short answer type questions as well in which you have to match the correct answer.
  • You are also asked to differentiate between direct and indirect development and intracellular and extracellular digestion. 

Refer to our NCERT Solutions for Class 11 Biology Chapter 4 and find all the right answers to this chapter. These solutions will not only maximize your academic performances but also it would equally boost your knowledge in the long run. All the best for your examinations.