Important Questions Class 11 Biology Chapter 4 Animal Kingdom

Important Questions Class 11 Biology Chapter 4 Animal Kingdom

Animal Kingdom is Chapter 4 of Class 11 Biology. It explains the basis on which animals are classified, such as levels of organisation, body symmetry, coelom (body cavity), segmentation and notochord. The chapter then describes the main phyla from Porifera to Chordata with examples.

This page gives 12 important questions from Animal Kingdom with clear answers prepared by Extramarks experts. The questions cover the steps to classify a specimen, the coelom, intracellular and extracellular digestion, direct and indirect development, features of arthropods, chordates, air bladder in fishes and flight adaptations in birds. Students can use them for school tests and CBSE (Central Board of Secondary Education) exam revision, and teachers and parents can use them for quick practice.

Q1. If you are given a specimen, what are the steps that you would follow to classify it?

Answer: Taxonomy is the study of principles and procedures of classification. Classification is the arrangement of living things according to their similarities and differences which bring order in the vast assemblage of living things in the world. A specimen can be classified in a stepwise process using the following classification categories:

Classification categories of animals - Class 11 Biology

Q2. How useful is the study of the nature of the body cavity and coelom in the classification of animals?

Answer: Coelom is a fluid-filled cavity formed between the gut wall and the body wall lined by the mesodermal cells. Presence or absence of coelom is an important criterion for animal classification. The animals with bilateral symmetry are further classified into three types of groups based on the presence or absence of coelom. They are as follows:

  1. Coelomates: In these animals, true coelom lined by mesoderm is present. E.g. Annelids, Arthropoda, Mollusca, Echinodermata, Hemichordata, Chordata
  2. Pseudocoelomates: In these animals, the body cavity is not lined by mesoderm instead the mesoderm is present in scattered pouches between the ectoderm and the endoderm. E.g. Aschelminthes
  3. Acoelomates: In these animals, body cavity is absent. E.g. Platyhelminthes

Coelomate pseudocoelomate acoelomate - Class 11 Biology

Q3. Distinguish between intracellular and extracellular digestion?

Answer:

Intracellular digestion Extracellular digestion
Digestion takes place within the cytoplasm of the organism. There is no alimentary canal. Digestion takes place in the alimentary canal of the animal.
Digestive enzymes are secreted in the food vacuoles. Digestive enzymes are secreted in the cavity of the alimentary canal.
It is not a very efficient process. It is an efficient process.
Most organisms that use intracellular digestion belong to Kingdom Protista, such as amoeba and paramecium. Simple multicellular animals that belong to the phylum Porifera (sponges) also show intracellular digestion. All multicellular organisms except sponges show an extracellular form of digestion. E.g. Annelids, Crustaceans, Arthropods, and Chordates.

Q4. What is the difference between direct and indirect development?

Answer:

Direct development Indirect development
In direct development, larval stage is absent, the embryo develops into a mature organism (looks like a miniature adult) without entering into the larval stage. Indirect development has a larval stage that is morphologically distinct from the adult.
In direct development, metamorphosis is absent. A process called metamorphosis transforms the larva into a mature adult.
It is found in fishes, reptiles and mammals. It is found in invertebrates and amphibians.

Q5. What are the peculiar features that you find in parasitic platyhelminthes?

Answer: The peculiar features of parasitic platyhelminthes are as follows:

  1. Hooks and suckers are present to attach to the wall of the gut.
  2. They have an extra coating (of glycocalyx) to protect themselves from being digested in the gut.
  3. They absorb nutrients from the host directly through their body surface. Their digestive systems are less evolved as compared to the free-living platyhelminthes.
  4. Locomotory organs like cilia and sensory organs like the primitive eye are absent in the parasitic forms of flatworms.
  5. Parasitic flatworms are mostly hermaphrodite ensuring reproduction in the host. The reproductive capacity is enhanced with most of their body lumen packed with testes and eggs.

Q6. What are the reasons that you can think of for the arthropods to constitute the largest group of the animal kingdom?

Answer: Arthropoda is the largest phylum of animal kingdom. Over two-thirds of all known species on earth are arthropods. The following are the reasons for arthropods to constitute the largest group of the animal kingdom:

  1. Arthropods are very diverse in structure and form.
  2. Their diversity in form is responsible for their dispersion into varied habitats. Arthropods are known to inhabit the ocean depths to the tallest mountain peaks.
  3. Their hard exoskeleton made of chitin is tough and protects the animal from extreme dryness. The exoskeleton is also insoluble in water, weak alkaline and acidic solutions.
  4. They have joint appendages that allow for efficient and precise movements. Many appendages are modified to meet the need of the arthropod for a specific foraging behaviour or a habitat.
  5. Their reproductive cycle is short and the female lays numerous eggs at one time.

Q7. “All vertebrates are chordates but all chordates are not vertebrates”. Justify the statement.

Answer: To understand the above statement, one needs to define the two words – notochord and vertebra – from which the terms chordates and vertebrates are derived.

Notochord: The notochord is a flexible rod-shaped structure found in embryos of all chordates.

Vertebral column: The vertebral column, also known as backbone or spine, is a bony structure found in vertebrates. It is formed from individual bones called vertebrae.

Chordata is a phylum which is divided into three subphyla - Urochordata, Cephalochordata and Vertebrata. All the chordates at some point of their lives possess a notochord. However, in vertebrates, this notochord is replaced by the vertebral column in the adult stage. Hence, it is right to state that “All vertebrates are chordates but all chordates are not vertebrates”.

Q8. How important is the presence of air bladder in Pisces?

Answer: Air bladder or swim bladder is a sac filled with air that regulates buoyancy in fishes. It plays a very important role in Pisces. The fishes (like Osteichthyes) where air bladder is present, it plays the following roles:

  • The air bladder controls the buoyancy by enabling the fish to stay at a particular water depth without having to waste energy in swimming continuously.
  • It acts as a resonating chamber to produce or receive sound.

In another kind of fishes (like Chondrichthyes), the air bladder is absent. Therefore these fishes have to swim constantly to avoid sinking resulting in the consumption of a lot of energy.

Q9. What are the modifications that are observed in birds that help them fly?

Answer: Some of the modifications that help birds to fly are listed below:

  1. The forelimbs are modified into wings.
  2. Birds have feathers that help them fly, steer and balance.
  3. Long bones are hollow with air cavities making their body weight light.
  4. Birds have air sacs that connect to the lungs and provide them with additional oxygen which is essential for flying.
  5. Birds have well-developed eyesight and brains that help them gauge any approaching danger as well as to forage for food.

Q10. Could the number of eggs or young ones produced by an oviparous and viviparous mother be equal? Why?

Answer: An oviparous mother lays more eggs at one time as compared to the number of offspring a viviparous mother gives birth to at any given time. This is because of the following reasons:

  • In oviparous mother, the eggs are laid soon after fertilisation, or eggs are externally fertilised. Therefore many eggs can be laid at one time. This also provides an evolutionary advantage as many eggs are liable to be eaten, destroyed during the period of development.
  • In the case of the viviparous mother, she has to house the embryo in the uterus till the full term of development. The embryo also draws nutrition from its mother. The mother thus is constrained by space in the uterus.

Q11. 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:

(a) Operculum (viii) Osteichthyes
(b) Parapodia (v) Annelida
(c) Scales (iv) Reptilia
(d) Comb plates (i) Ctenophora
(e) Radula (ii) Mollusca
(f) Hair (vii) Mammalia
(g) Choanocytes (iii) Porifera
(h) Gill slits (vi) Cyclostomata and Chondrichtyes

Q12. Prepare a list of some animals that are found parasitic on human beings.

Answer:

Endoparasite -
Cause infection inside the body		 Worms
Taenia(Tapeworm), Parasitic worms can cause a number of problems, including diarrhoea, fatigue, skin rash, nervousness, asthma and anaemia.
Fasciola(Liver fluke).
Ascaris(Round Worm)
Wuchereria(Filaria worm)
Ancylostoma(Hookworm)
Protozoa
Plasmodium Malaria
Entameoba Amoebiasis
Trypanosomabrucei African sleeping sickness
Ectoparasites – Cause infection within the skin Pediculushumanuscapitis Head lice
Phthitus pubis Pubic lice

Related Study Material on Extramarks

Q.1  Identify the phylum based on the given characteristics.

i. These are aquatic or terrestrial, free-living or parasitic animals.

ii. These are triploblastic animals and first-true coelomates.

iii. They possess metameric segmentation.

iv. Locomotion in these animals takes place by setae, parapodia or suckers.

Marks:1
Ans

Annelids are free-living, terrestrial or aquatic (marine or freshwater) animals. They are triploblastic animals consisting of three germ layers. They have a ?true coelom? lined with mesodermal peritoneum. The body of annelids is divided into repeated segments known as metamers. The locomotion in these animals takes place by setae (e.g., Earthworm), parapodia (e.g., Nereis) or suckers (e.g., Leech).

Q.2 Which of the following statements are correct for a tapeworm?

1. Possesses setae for locomotion

2. Gas exchange takes place through the general body surface

3. Possesses an organ for attachment with the body of the host

4. A digestive system is absent

Marks:1
Ans

In phylum Platyhelminthes, respiratory system and digestive system are absent. Gas exchange takes place through the general body surface. These animals draw the nutrients from the host. They possess suckers for attachment with the body of the host.

Q.3 Which of the following characters are commonly found in centipede, cockroach and crab?

Marks:1
Ans

Centipede, cockroach and crab share common characters: jointed legs (three pairs) and an external hard chitinous exoskeleton.

Q.4 In the given table, different animals and the number of their heart chambers are given. Choose the correct combination.

Marks:1
Ans

In fish, the heart contains one atrium and one ventricle, i.e., their heart is two-chambered. In amphibians (frog), the heart contains two atria and one ventricle, i.e., their heart is three-chambered. In reptiles (snake), the heart contains two atria and one partially divided ventricle, i.e., their heart is three-chambered. In birds, the heart contains two atria and two ventricles, i.e., their heart is four-chambered.

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