Animal Kingdom Class 11 Biology Chapter 4 Question Answers

Biology studies various multidisciplinary phenomena of the universe and its constituents. Animal Kingdom is a key fundamental concept in the scientific concepts of Biology. Animals are classified based on the basis of fundamental features, which is the key underlying feature of the study of the animal kingdom.  Some of these features are cellular arrangement, body symmetry, presence or absence of the coelom, and specific features of the circulatory, respiratory, and digestive systems.

One observes many animals with various shapes and structures when one looks around. With over a million animal species identified to date, the necessity for categorisation becomes even more critical. Categorisation helps in understanding the ecosystem systematically, which makes defining and placing newly described species in a logical order. Taxonomy is a study of classifying these creatures. Each species identified to date is divided into five kingdoms, one of which is the Animal Kingdom. Depending on distinguishing characteristics, animal kingdom members are further divided into distinct Phyla, Classes, Orders, Families, and Geniuses.

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The questions in our question bank of Important Questions Class 11 Biology Chapter 4 include: Animal Kingdom majorly deals with the classification of the animal kingdom based on different features at the Cellular Level, Tissue level, Organ level, Organ-System level, and many other things.

These questions are based on the key concepts and the vital points covered in the Important Questions Class 11 Biology Chapter 4. These key concepts give students a very clear understanding of each concept they have learnt and help them retain it for a long time. As a result of understanding better and retaining a lot of content due to repeated revisions, students develop a very good command of the subject and thus they score very well in their examinations.

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Class 11 Biology Chapter 4 Important Questions and Answers

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The following are some of the important questions and their solutions that have been picked from the Important Questions Class 11 Biology Chapter 4.

Q1. Distinguish between intracellular and extracellular digestion.

Solution 1 – 

Intracellular digestion occurs inside the cell in lower organisms. There is a breakdown of complex food materials into simpler ones inside the cell. While on the other hand, extracellular digestion occurs outside the cell in the lumen cavity. It occurs in multicellular organisms, where many digestive glands and enzymes are required to properly break down complex food material. 

Q2. What are the significant features that you find in parasitic Platyhelminthes?

Solution 2 – 

The most significant features of the parasitic Platyhelminthes are:

(i)They are free-living and parasitic.

(ii) They contain an organ level of organisation and are mostly hermaphrodites.

(iii) Their body wall is three layers, with the epidermis being the outer covering made up of ciliate and covered with cuticles.

(iv) The digestive tract is incomplete or absent

(v) There is the presence of well-defined excretory structures, such as flame cells.

(vi) Presence of anti-toxins and a thick tegument resistant to the host’s digestive enzymes. 

(vii) They are classified into anaerobic respiration, which means they can survive without air. No special respiratory structure was observed.

(viii) Their front body is divided into suckers, hooks, eyespots and auricles that help them to attach themselves to the hosts.

(ix) A highly developed reproductive system.

Q3. The unique water vascular system is the characteristic of which group of the following:

(a) Porifera 

(b) Ctenophora

 (c) Echinodermata

 (d) Chordata

Solution 3 – 

The correct option is (c ) 

Explanation: The species Echinodermata contains a perforated panel known as madreporite, which allows the water to perfoliate or travel inside the body.

Q4.All vertebrates are termed chordates, but all chordates are not vertebrates. Justify the statement.

Solution 4 

The phylum Chordata has two special features, the presence of Notochord and paired pharyngeal gill slits. However, most adults replace the vertebrate Notochord in the embryo in the subfile with the columns of the bony vertebrae. It is, therefore, classified as, “All vertebrates are chordates, but not all chordates are vertebrates.”

Q5. What are the unique modifications observed in birds that help them fly?

Solution 5 – 

Birds are a species that are characterised by the presence of feathers. The special modification observed in birds that help them to fly is that their forelimbs are converted into wings, which help them to fly, while their hind limbs have scales. 

They have pneumatic, also known as hollow bones, that lighten the skeleton and do not contain a urinary bladder which causes net body weight loss and facilitates them to fly more freely. They also contain a streamlined body which provides less resistance and enables longer flight. 

Q6. Can the number of eggs or young ones produced by an oviparous and viviparous mother be equal? Why?

Solution 6 – 

No, the number of young ones which an oviparous and viviparous mother produces are not equal. The number of young ones produced by oviparous mothers is more than that of viviparous animals. Because in most oviparous animals, Fertilisation takes place outside the uterus, whereas in viviparous animals, Fertilisation and development of the zygote take place inside the uterus, which results in the successful incubation of young animals. 

When eggs are present outside in nature, there is a high risk of eggs being consumed by predators. Therefore, to sustain the progeny, more eggs are required. 

Q7. Why do arthropods constitute the largest group in the animal kingdom?

Solution 7:

Arthropods constitute the largest group in the animal kingdom due to the following reasons – 

(i) They are motile animals, meaning they have joint legs, which help them perform many other functions.

(ii) Their skeleton is made of chitin which protects their body as the chitin material is very hard.

(iii)Their hard skeletons reduce water loss from the body.

(iv) They have three different locomotion, respiration and reproduction systems.

(v) They can live in diverse conditions and varied habitats.

(vi) Compared to other species, they are pre-developed and have well-developed sense organs and nervous systems.

Q8. Which of the following sets of animals defined below belongs to a single taxonomic group?

1. Cuttlefish, Jellyfish, Silverfish, Dogfish, Starfish
2. Bat, Pigeon, Butterfly
3. Monkey, Chimpanzee, Man
4. Silkworm, Tapeworm, Earthworm

Solution 8 – Option (c ) is the right answer.

Explanation – Monkeys, chimpanzees and men have many similar characteristics and are placed in one common group.

Q9. Which one of the given following statements is not correct?

1. In cockroaches and prawns, waste materials and product excretion occur through the malpighian tubules.
2. In ctenophores, the locomotion is mediated by eight comb plates.
3. In Fasciola, there are special flame cells which help in the process of excretion
4. Earthworms are hermaphrodites in nature, yet cross-fertilisation occurs among them.

Solution 9: Option (a ) is the right answer.

Explanation- In prawns, the excretory organ is paired with a green gland.

Q10. Distinguish between the following terms-  

1. Closed circulatory system and Open circulatory system. 
2. Oviparous and viviparous characteristics 
3. Direct development and Indirect development

Solution10:

1. a) In the open circulatory system, the blood is pumped out of the heart, flows freely through cavities and is not confined to blood vessels. It is mainly found in vertebrates. . In contrast, blood is circulated throughout the body with the help of a series of vessels in the closed circulatory system. It is present in vertebrates and echinoderms.
2. b) Laying fertilised and unfertilised eggs are called oviparous animals, whereas giving birth to young ones is classified under viviparous animals.
3. C) In direct development, the larval stage is absent, and there is an incomplete development of the organism. In contrast, the larval stage is present in the organism’s development, which does not resemble the adult, called indirect development. 

Q11. Differentiate between – 

• Open and closed circulatory system
•  Oviparity and viviparity
• Direct and indirect development
•  Acoelomate and pseudocoelomate
•  Notochord and nerve cord
• Polyp and Medusa

Solution 11. 

1. a) In the circulatory system, the blood is pumped out of the heart, and flows freely through cavities and is not confined to blood vessels. It is mainly found in vertebrates. In contrast, blood is circulated throughout the body with the help of a series of vessels in the closed circulatory system.It is present in vertebrates and echinoderms.
2. b) Laying fertilised and unfertilised eggs are called oviparous animals, whereas giving birth to young ones is classified under viviparous animals.
3. C) In direct development, the larval stage is absent, and there is an incomplete development of the organism. In contrast, the larval stage is present in that organism which fails to resemble the adult. This is termed indirect development. 
4. d) Coelomates are animals that do not possess a coelom, whereas pseudocoelomates contain a mesoderm layer which is present in between ectoderm and endoderm.
5. e) The Notochord is a mesodermally derived rod-like structure which is formed on the dorsal side during embryonic development, whereas the nerve cord is a solid strand of nervous tissue
6. f) Polyp is sessile and cylindrical. one of its most common examples is Hydra, Whereas, on the other hand, Medusa is umbrella shape and 

free summing in nature. Its most common example is Jellyfish.

Q12. What is the relationship between the germinal layers and the body cavity formation in the case of coelomates, acoelomates and pseudocoelomates?

Solution 12:

Germinal layers are those formed during the process of gastrulation. The outer layer of the germ is called the ectoderm, the middle one is the endoderm, and the innermost is the endoderm. Coelomates are organisms that possess coeloms. The coelom is the body cavity which is lined by the mesodermal layer. Annelida, Mollusca, arthropods, etc., are the most common examples of coelomates. The organisms with absent or no body cavities are called acoelomates. One of the most common examples of acoelomate is Platyhelminthes. Some of these organisms do not have a mesoderm lining. Instead, it will be in the form of a scattered pouch between the ectoderm and endoderm layers. Such a body cavity is called pseudocode, and animals possessing pseudocolour are called pseudocoelomates. E.g., Ascaris. 

Q13. Mammals are the most adapted species among the class of vertebrates. Why?

Solution 13 – 

Mammals are the species found in various habitats like deserts, plains, and mountains. They differ in the type of jaws; their sexes are separate, and the fertilisation is internal. They contain a pair of limbs that help in walking, burrowing, and climbing. They have special glands called mammary glands that produce milk to nourish their young ones. They can maintain their body temperature in different weather conditions, so they are warm-blooded. They have hair-like structures which act as insulation against cold. The 4-chambered heart is present in mammals. The brains are more developed. Examples of mammals are Humans, Whales, Dogs and Camels. 

Q14. Birds and mammals share one common feature. What is that common feature from the following characteristics given below?

(a) Pigmented Skin

(b) Pneumatic bones

(c) Viviparity

(d) Warm-blooded nature

Solution 14 – Option (d) is the right answer.

Explanation: Birds and mammals both are warm-blooded. They can maintain their body temperature in different weather conditions and are warm-blooded.

Q15. The body cavity is the cavity between the body and gut walls. In some animals, the body cavity is absent, while in some, it is present. To define the terms.

 (a) Acoelomate and 

(b) Pseudocoelomate.

(c) Coelomate 

Solution 15 –

(i) Acoelomate: Acoelomates are animals in which the body cavity is absent. E.g., Porifers, Coelenterates, Ctenophores and Platyhelminthes.

(ii) Pseudocoelomate: The mesoderm is not lined in some animals. Instead, the mesoderm is present as scattered pouches between the ectoderm and endoderm. Here the body cavity is directly connected to the archenteron. Such a body cavity is known as pseudocolour, and pseudocoelomates are the animals possessing the body cavity examples are Aschelminthes, also known as Ascaris.

(iii) Coelomate: In coelomate animals, the coelom is the body cavity lined by mesoderm on both sides. Animals possessing coelom are called coelomates, the cavity between the alimentary canal and body wall enclosed by mesoderm on both sides. E.g., Annelids, Arthropods, Molluscs, Echinoderms, Hemichordates and Chordates.

Depending upon its origin, true coelom or coelom is of two types:

(a) Schizocoelous: The coelom is formed by the splitting of mesoderm. E.g., Annelida, Arthropoda and Mollusca.

Note: The cavity filled with blood is called haemocoel. It is found in Arthropods (cockroaches) and Molluscs (Pila).

(b) Enterocoelom: The coelom develops as an outgrowth of the enteron or embryonic gut. E.g.: Deuterostomia (Echinodermata and Chordata). Echinodermata is an enterocoelomate invertebrate.

Q16. Write one example of each of the following in the space provided.

1. Cold-blooded animal
2. Warm-blooded animal
3. An animal possesses dry and cornified skin
4. Dioecious Animal

Solution 16- 

Examples:

1. Cold-blooded Animal: amphibians (Frog)
2. Warm-blooded Animal: mammals (humans)
3. An animal possessing dry and cornified Skin: reptiles (Lizard)
4. Dioecious animal: aschelminthes (Ascaris)

Q17. Differentiate between the features of a diploblastic and a triploblastic animal.

Solution 17- 

 (i) Diploblastic: Animals are animals in which the cells are arranged in two embryonic layers, external ectoderm and an internal endoderm. e.g. Porifers, ctenophores and coelenterates.

(ii) Triploblastic: triploblastic animals are those animals in which there is a developing embryo that has a third germinal layer called mesoderm, in between the ectoderm and endoderm. E.g., Platyhelminthes to Chordates.

Q18. Endoparasites are found inside the host body. Mention the special structure these possess, which enables them to survive in those conditions.

Solution 18 – 

 Because of their extreme specialisation, the life cycles of endoparasites are more complex. Their morphological and anatomical features are mostly simplified while emphasising their reproductive potential.

Following their lifestyle, parasites evolve special adaptations, which include:

1. Loss or absence of unnecessary sense organs.
2. Absence of digestive system.
3. A high reproducing capacity.
4. Presence of suckers, also called adhesive organs, that help cling onto the host.

Q19. Give the main characteristic features of the following, citing one example of each:

1. Chondrichthyes and Osteichthyes
2. Urochordata and Cephalochordata

Solution 19

1. Chondrichthyes-. They are marine animals with streamlined bodies and have cartilaginous endoskeletons. The mouth is located ventrally. The Notochord is present throughout life. Their gill slits are separate and without a gill cover, also called an operculum. Their skin is tough as they contain minute placoid scales. Their teeth are modified as placoid scales, which are backwardly directed. Their jaws are very powerful. These animals are predaceous. Due to the absence of an air bladder, they must constantly swim to avoid sinking. Scoliodon (Dogfish), Pristis (Sawfish), Carcharodon (Great white shark), and Trygon (Stingray).

Osteichthyes: It includes both marine and freshwater fishes with a bony endoskeleton. Their body is streamlined. The mouth is located terminally. They contain four pairs of gills covered by an operculum on each side. Skin is covered with cycloid/ctenoid scales. The air bladder is present, which helps in the regulation of buoyancy.

Examples: Marine fishes – Exocoetus (Flying fish), Hippocampus (Sea horse); Freshwater—Labeo (Rohu), Catla (Katla), Clarias (Magur); Aquarium—Betta (Fighting fish), Pterophyllum (Angelfish),

1. Subphylum Urochordata and Cephalochordata are often classified as protochordate and are exclusively marine. In Urochordata, Notochord is present only in the larval tail. On the other hand, in Cephalochordata, the Notochord is persistent throughout their life and extends from head to tail region. 

Examples: Urochordata – Ascidia, Salpa, Doliolum; Cephalochordata— Branchiostoma (Amphioxus or Lancelet).

Q20. Give an example of the following –

1. An example of a limbless animal. 
2. An example of a cold-blooded animal
3. An example of a warm-blooded animal
4. Which Animals possess dry and cornified Skin
5. Which Animals have a canal system and spicules
6. An animal with cnidoblasts

Solution 20 – 

1. A limbless animal: Ichthyophis
2. A cold-blooded animal: Trygon (stingray)
3. Macaca (monkey) is a warm-blooded animal.
4. Naja (Cobra) is an animal possessing dry and cornified Skin.
5. An animal has a canal system and spicules: Euspongia (bath sponge)
6. An animal with cnidoblasts: Hydra.

Q21. Give an example:

1. A viviparous animal
2. A fish possesses a poison sting
3. A fish possesses an electric organ
4. An organ which regulates buoyancy
5. Animal, which exhibits alternation of generation
6. Oviparous Animal with mammary gland.

Solution 21 – 

1. A viviparous animal is Panthera leo, also known as a lion. 
2. A fish possessing a poison sting is called Trygon, known as a sting ray.
3. A fish possessing an electric organ is called a Torpedo
4. An organ which regulates buoyancy is called an Air bladder
5. An Animal which exhibits alternation of generation is called Obelia (Sea-fur)
6. Oviparous Animal with a mammary gland is called Echidna (Platypus).

Q22. Comment upon the significant features of animals belonging to class, amphibia and reptilia.

Solution 22

 Class—As their name indicates, Amphibia means dual life, meaning most amphibians can exist in aquatic and terrestrial habitats. The majority of them have two pairs of limbs that help in locomotion. The body is divided into the head and trunk, and the tail may be present in some. The amphibian skin is moist and does not contain scales. They contain eyelids and a tympanum which represents the ear.

Cloaca is the common chamber through which the alimentary canal, urinary and reproductive tracts open. Further, the cloaca opens to the exterior surface through a cloacal aperture. Respiration may occur by gills, lungs, or through the surface called Skin. The heart is three-chambered (2 auricles and one ventricle). These are cold-blooded animals.

The Sexes are separate, and their Fertilisation is external. Also, they are oviparous(egg produced outside the body), and development is either direct or indirect based on the larva.

Examples of Amphibia are Bufo (Toad), Rana (Frog), Hyla (Tree frog) etc.

Class-Reptilia: Reptilia refers to their creeping or crawling mode of locomotion (Latin, repair or rectum, to creep and crawl). They are mostly classified as terrestrial animals, and epidermal scales or scutes cover their body, so they contain dry and cornified skin. They do not have external ear openings called pinnae. Nor do they containTympanum, which represents the ear. Limbs, when present, are mostly present as two pairs.

Examples: Chelone, also known as Turtle.

Testudo (Tortoise)

 Chameleon (Tree lizard)

Calotes (Garden lizard)

Crocodilus (Crocodile)

 Alligator (Alligator)

Hemidactylus (Wall lizard)

Poisonous snakes – Naja (Cobra)

 Bungarus (Krait), Vipera (Viper).

Q23. Mention two significant modifications in reptiles which are required for terrestrial mode of life.

Solution 23 

1. Their body is covered by dry Skin. Also known as epidermal scales or scutes.
2. Cleidoic eggs

Q24. Mention one example of the animal with a chitinous exoskeleton and those covered by a calcareous shell.

Solution 24 

A chitinous exoskeleton covers the body of arthropods (like a cockroach), and a calcareous shell covers the molluscan (like Pila) body.

Q25. In some animal groups, the body is divided into different compartments with a serial repetition of at least some organs. This characteristic feature is called – 

1. Segmentation
2. Metamerism
3. Metagenesis
4. Metamorphosis

Solution 25- Option (b ) is the correct answer.

Explanation: –

The body in some animals is externally and internally separated into fragments with a serial repetition of at least some organs. This is the phenomenon of metamerism. 

For example, in an earthworm, the body shows the phenomenon of metamerism. If we talk about the process of Metagenesis, it is the reproduction cycle of an organism alternating between sexual and asexual modes. 

Q26.Given below are different types of cells which are present in some animals. Which of the following cells stated below can differentiate and perform other functions?

1. Choanocytes
2. Interstitial cells
3. Gastrodermal cells
4. Nematocysts

Answer:  Option (b ) is the right answer. 

Explanation: –

Interstitial cells in the ovary and testes can differentiate. Interstitial cell refers to any cell that lies in the places amid the functional cells of a tissue.

Q27. Name the Animals which exhibit the phenomenon of bioluminescence. Mention the species to which it belongs.

Solution 27

Bioluminescence is a phenomenon that involves the emission and production of light by any organism. This results from a chemical reaction that converts the chemical energy into light energy—animals like Pleurobrachia and Ctenoplana exhibit the process of bioluminescence.

These animals belong to phylum ctenophores like Ctenoplana, Velamen, Beroe, etc.

Q28. What is Metagenesis? Mention an example which exhibits this phenomenon.

Solution 28 – 

Metagenesis is a phenomenon defined as the reproduction cycle of an organism alternating between sexual and asexual modes.

Q29.What is the role of feathers?

Solution 29.

Feathers are a significant characteristic of Aves, which help in flying by reducing the body’s overall weight. They generate an airfoil shape with the wings, which help in flying. Most commonly present In Aves, besides pneumatic bones, feathers are also helpful in making the body weigh lighter and help in flight.

Feathers are also helpful in mating.

Q30.Which group of chordates possess a sucking and circular mouth without jaws?

Solution 30.

Cyclostomes have sucking and circular mouths that do not contain jaws. That’s why they are mostly known as jawless fish. The most common shape of their mouth is circular, and as they lack jaws, they are also called agnathans.

Q31.Give a reason why a snail & an octopus are classified under the same phylum. 

Solution 31- 

Snails & octopuses are classified under the phylum Mollusca because they have the following three characteristics: 

(i)Presence of mantle in both

 (ii)Presence of foot in both 

(iii)Presence of shell in both

Q32. Discuss the different levels or grades of the organisation.

Solution 32:

The kingdom Animalia includes multicellular heterotrophic animals, which exhibit cellular, tissue and organ level of organisation as classified below.

Cellular Level of organisation – Animals such as sponges, which are loose associations of cells, fall into this group. Some division of labour occurs between these cells, but these cells do not organise themselves into a definite tissue.

The tissue Level of the organisation is defined as animals with specialised cells grouped to form specific tissue, like animals from ctenophores and cnidarians. 

Organ Level of organisation – Animals that contain different kinds of tissues which are further organised into distinct organs, each specialised for a specific function, come under the organisation’s organ level. e.g. Platyhelminthes.

Organ-system Level of the organisation is defined as animals that have organs grouped into functional systems. Each system is primarily concerned with a specific function placed in this group, e.g., some platyhelminthes, annelids, molluscs, arthropods, echinoderms, and chordates.

Q33. Discuss the types of patterns present in the organ system of the organisation. 

Solution 33. 

The various patterns of the complexity of organ systems serve as one useful criterion in classifying animals. For example, the digestive system may be complete, incomplete or absent. An incomplete digestive system results in only a single opening to the outside body, which serves as both mouth and anus. A complete digestive system has two openings: the mouth and anus.

Similarly, the circulatory system is classified into two types.

First is the open Type, where blood is pumped out of the heart and directly bathes the cells and tissues. 

The second is the closed Type, in which the blood is circulated through a series of tubes of varying diameters (arteries, veins, and capillaries).

Q34. Describe the significance and term Cnidaria. 

Solution 34- 

Cnidaria is classified as animals which are aquatic or mostly marine. They are sessile or free-swimming animals that are diploblastic. The phylum name Cnidaria is derived from the stinging cells called nematocysts or cnidoblasts on the ectoderm of tentacles and the bodies of these predatory animals. Cnidoblasts are used for anchorage, defence, and the capture of prey. They exhibit tissue level of organisation and radial symmetry. 

The digestive system is incomplete. They have a central gastro-vascular cavity with a single opening, the mouth. Digestion is extracellular and intracellular. Some of the cnidarians, e.g., corals, have skeletons composed of calcium carbonate.

Cnidarians exhibit two basic body forms: a polyp (e.g., Hydra) and Medusa (e.g., Auralia). The former is sessile and cylindrical, whereas the latter is umbrella-shaped and free-swimming. Those cnidarians which exist in both forms exhibit alternation of generation, i.e. polyps asexually produce medusae and medusae forming the polyps sexually (e.g., Ophelia)

Examples of Cnidaria: Hydra, Porpita, Vellala, Physalia (Portuguese man-of-war), Aurelia (Jellyfish), Adamisia (Sea anemone), Pennatula (Sea- pen), Gorgonia (Sea-fan), and Meandrina

Q35. Describe the important characteristics of Aves.

Solution 35:

The significant features of birds are the presence of feathers that help them to fly, and while most of them can fly, there are a few exceptions, generally called flightless birds (e.g. Ostrich). They possess beaks. Their forelimbs are modified into wings, while their hind limbs generally contain scales which are further modified for walking, swimming, and clasping the tree branches. Their skin is dry because they do not contain any glands except the oil gland, which is situated below the tail. Their endoskeleton is fully ossified and bony, and the long bones are hollowed as they are filled with air cavities.

Their digestive tract has additional chambers known as the crop and the gizzard. They contain a complete four-chambered heart. They are warm-blooded, i.e. homeothermic animals. They can maintain a state of constant body temperature. The lungs are their main respiratory organ. And birds have good vision.

 The kidney is their main excretory organ. Their sexes are separate, and fertilisation is internal, which means they are oviparous, and development is directly dependent on the larva stages. Common Examples of Aves are Corvus (crow), Columba (pigeon), Prittacula (parrot), and Struthio (Ostrich).

Q36.Explain the important characteristics of Mammalia.

Solution 36 – 

Mammalia is generally terrestrial animals found in various habitats such as polar ice caps, deserts, mountains, evergreen forests, grasslands, and many dark cover. Some of them are even adapted to fly or live underwater. The unique mammalian characteristic of mammalians is the presence of milk-producing glands called mammary glands, through which the young ones are provided nourishment.

Mammalia contains two pairs of limbs adapted for different purposes like walking, running, climbing, swimming, and flying. The Skin of mammals possesses hairs containing external ears called pinnae. Four different types of teeth are present in the buccal cavity. And the heart is four-chambered. Also, the respiratory system is well developed. 

Their sexes are separate, and fertilisation is internal, which means they are viviparous with few exceptions, and development is direct.

Q37. Explain the term amphibia.

Solution 37:

As their name indicates, Amphibia means dual life, which means most amphibians can exist in aquatic and terrestrial habitats. The majority of them have two pairs of limbs that help in locomotion. The body is divided into the head and trunk, and the tail may be present in some. The amphibian skin is moist and does not contain scales. They contain eyelids and a tympanum which represents the ear.

Cloaca is the common chamber through which the alimentary canal, urinary and reproductive tracts open. Further, the cloaca opens to the exterior surface through a cloacal aperture. Respiration may occur by gills, lungs, or through the surface called Skin. The heart is three-chambered (2 auricles and one ventricle). These are cold-blooded animals.

The Sexes are separate, and their Fertilisation is external. Also, they are oviparous(egg produced outside the body), and development is either direct or indirect based on the larva.

Examples of Amphibia are Bufo (Toad), Rana (Frog), Hyla (Tree frog) etc.

Q38. Describe the phylum Arthropods.

Solution 38:

Arthropoda is the largest species in the animal kingdom, consisting of more than 900,000 species, including many insects.

Arthropoda has an evolved organ-system level of body organisation. They contain many significant characteristics, like bilaterally symmetrical, triploblastic in nature and segmented. They do not contain coelom, so they are acoelomate animals.

The exoskeleton of arthropods is formed by a chitinous cuticle which helps in protection. The body segments are fused to form the head, thorax, and abdomen.

They have jointed appendages. The appendages are variously classified to form different body parts like antennae, mouthparts, and pincers (chelicerae), also known as walking legs.

Their digestive system is complete.

They contain respiratory organs like the gills or tracheal system.

The circulatory system consists of an open type, and its nervous system is almost similar to that of the annelids. Sensory organs include antennae for perceiving odour, receptors for taste, eyes (two main types -compound and simple) for vision, and sound receptors. They contain Malpighian tubules from the process of excretion. They are mostly dioecious n nature with sexual reproduction. Fertilisation is mostly internal. They are usually oviparous.

Their development may be direct or indirect, depending on the larval stages. Also, metamorphosis is the process of transformation of a larva into an adult.

Examples of the phylum Arthropoda are Periplaneta (Cockroach), Apis (Bee), Anopheles (Mosquito), Limulus (King crab) etc. 

Q39. Differentiate between bilateral Symmetry and radial symmetry 

Solution 39:

Most animals are grouped into two different categories based on their symmetry. Radial Symmetry is when any plane passing through the body’s central axis divides the organism into halves like a mirror image. The common examples of the same are Cnidarians, ctenophores, and echinoderms.

On the other hand, animals like annelids, arthropods, etc. It exhibits bilateral Symmetry, where the body can be divided into identical left and right halves in only one plane. 

Q 40. Which plants have mycorrhizal and coralloid roots? What exactly do these words imply?

Solution 40. Mycorrhiza is a symbiotic relationship between fungi and vascular plant roots. Conifers such as Pinus, Cedrus, and others have a mycorrhizal relationship. In Cycas, there are coralloid roots. Coralloid roots extend above the ground and are found in clusters at the base of the stem. It has a greenish colour and a dichotomous branching pattern.

Q 41. Which organ helps excretion in (i) Arthropods and (ii) Hemichordates?

Solution 41. Organs of excretion in Arthropods: – Malpighian tubules,

Organs of excretion in Hemichordates: – Proboscis gland.

Q 42. Name free-living & parasitic Platyhelminthes.

Solution 42 

(i) Free-living Platyhelminthes: – Planaria (Freshwater flatworm)

(ii)Parasitic Platyhelminthes: – Taenia (Tapeworms)

Q 43. What is metamerism?

Solution 43. In some Bilateria, the body consists of many segments & shows repetitions of parts. This type of segmentation is called metamerism.

Q 44. Assign the species to which the following animals belong – pheretima & sponge. 

Solution 44. Pheretima belongs to phylum Annelida & sponge belongs to phylum Sponge (Porifera).

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