Reproduction in Animals Class 8 Important Questions and Answers
Important questions of Class 8 Science Chapter 9 Reproduction in Animals is given below. These important questions will help students while preparing for the exam. Practising these important questions will analyse their performance and work on their weak points. Score well in exam of Class 8 Science by going through these important questions. Students of Class 8 can download important questions of Class 8 Science Chapter 9 Reproduction in Animals PDF by clicking the link provided below.
Important Questions of Class 8 Science Chapter 9 Reproduction in Animals
Here you can get Class 8 Important Questions Science based on NCERT Text book for Class 8. Science Class 8 Important Questions are very helpful to score high marks in board exams. Here we have covered Important Questions on Reproduction in Animals for Class 8 Science subject.
Very Short Answer Questions
1. Name the processes which are essential for the survival of individuals.
Answer: Digestion, circulation, excretion and respiration.
2. What do you mean by reproduction?
Answer: The process which is essential for the continuation of species is called reproduction.
3. What are different modes of reproduction?
Answer: (i) Sexual reproduction (ii) Asexual reproduction.
4. Define the term sexual reproduction.
Answer: The process of reproduction in which fusion of male and female gametes takes place is called sexual reproduction.
5. What is male gamete?
Answer: The reproductive cell produced by male reproductive organs is called male gamete.
6. What is female gamete?
Answer: The reproductive cell produced by female reproductive organs is called female gamete.
7. Name the male gamete.
Answer: Sperm.
8. What is name of the reproductive organ which produces sperm?
Answer: A pair of testes.
9. Name the female gamete.
Answer: Ovum or egg cell.
10. Which organ produces the ovum?
Answer: A pair of ovaries.
11. What do you mean by fertilisation?
Answer: The process of fusion of male and female gametes to produce zygote is called fertilisation.
12. Name male reproductive organs.
Answer: A pair of testes, two sperm ducts and a penis.
13. Write the names of female reproductive organs.
Answer: A pair of ovaries, oviducts and uterus.
14. What is the other name of oviducts?
Answer: Fallopian tubes.
15. How many types of fertilisation are there?
Answer: There are two types of fertilisation: (i) Internal fertilisation (ii) External fertilisation.
16. What types of fertilisation takes place in humans?
Answer: Internal fertilisation.
17. What type of fertilisation takes place in frog?
Answer: External fertilisation.
18. Write full form of IVF.
Answer: In Vitro Fertilisation.
19. What are test-tube babies?
Answer: The babies born through IVF technique are called test-tube babies.
20. What is embryo?
Answer: The developing zygote having group of cells that develop into tissues and organs, is called embryo.
21. Where does development of embryo take place in the body of female?
Answer: The embryo develops in the uterus of female reproductive organ.
22. What is foetus?
Answer: The well developed embryo is called foetus.
23. Where does the development of embryo take place in those animals which undergo external fertilisation?
Answer: Outside the female body in open
24. What are viviparous animals?
Answer: The animals which give birth to young ones are called viviparous animals.
25. What are oviparous animals?
Answer: The animals which lay eggs are called oviparous animals.
26. Give some examples of viviparous animals.
Answer: Cow, dog, cat and human beings.
27. Give some examples of oviparous animals.
Answer: Hen, lizards etc. and all birds.
28. What do you understand by metamorphosis?
Answer: The transformation of larva into adult through drastic changes is called metamorphosis.
29. Do we also undergo metamorphosis?
Answer: No, we do not undergo metamorphosis.
30. Define the term asexual reproduction.
Answer: When only single parent is involved in reproduction, then it is called asexual reproduction.
31. Name the various methods of asexual reproduction in animals.
Answer: (i) by budding (ii) by fission (iii) by regeneration (iv) by cloning.
32. Write an animal’s name in which asexual reproduction takes place by budding?
Answer: Hydra.
33. What type of reproduction takes place in amoeba?
Answer: Asexual reproduction by binary fission.
Short Answer Type Questions
1: Define Sexual reproduction.
Answer: Sexual reproduction: Reproduction which begins with the fusion of male and female gamete is called Sexual reproduction.
2: Define Fertilization.
Answer: Fertilization: Fusion of egg with sperm is called Fertilization.
3: What is Zygote?
Answer: Fusion of male and female gametes produce fertilize egg which is Zygote.
4: Define internal fertilization.
Answer: Fertilization which takes place inside female body is called internal fertilization.
5: What is in-vitro fertilization?
Answer: Fertilization done by doctors, outside the body, is called In-vitro fertilization?
6: How do the hundreds of eggs of frog remain protected even if laid on open aquatic system?
Answer: A layer of Jelly holds the eggs together and provides them protection.
7: What is External fertilization?
Answer: The type of fertilization in which fusion of male and female gametes takes place outside the body of female is called External fertilization. It takes place in animals like frog, lizard, fish etc.
8: Give two examples of organisms showing both internal and external mode of fertilization.
Answer: Internal fertilization: Human and Hen.
External fertilization: Frog and Starfish.
9: What are the common difference between zygote and embryo? .
Answer: Zygote: Single fertilizes egg and found in oviducts.
Embryo: Ball of cells and gets embedded in the wall of uterus for development.
10: Define Embryo.
Answer: Zygote divides repeatedly to give ball of cell called Embryo.
11: What is Foetus?
Answer: The stage of embryo in which all body part can be identified is a Foetus. When the development of foetus is complete, the mother gives birth to the baby.
12: What is the basic difference between reproduction mechanism in human being and hen?
Answer: Human being gives birth to baby, they are viviparous whereas hen lays egg and they are oviparous.
14: What is Viviparous animal?
Answer: The animals which give birth to young one are called Viviparous animal. Like cow, dog etc.
15: Explain Metamorphosis.
Answer: The transformation of larva into adult through drastic changes is called Metamorphosis.
16: Differentiate between internal fertilisation and external fertilisation.
Answer:
| External Fertilization | Internal Fertilization |
| Takes place outside the female’s body. | Takes place inside the female’s body. |
| Usually, a large number of gametes are released in the surrounding medium (for example water). | Male gametes are released inside the body of the female by a copulatory organ. |
| Organisms that use external fertilization to reproduce must either live in the water or return to the water for reproduction. | Animals that have internal fertilization have completely transitioned to life on land. |
| As the chance of fertilization in water is generally less, hence, a large number of gametes are released. | The number of gametes produced in this mode is relatively less. |
| Examples: Fish, Amphibians, and most of the Algae, etc. | Examples: Reptiles, Birds, Mammals, Bryophytes, and Tracheophytes. |
17: Differentiate between zygote and foetus.
Answer:
| Zygote | Foetus |
| It is formed by the fusion of the nuclei of the sperm and egg. | It is the stage of the embryo which nearly resembles a human being. |
| It is a unicellular structure. | It is a multicellular structure. |
| Produced after the processes of fertilization. | Produced after the processes of cell division and cell labour division. |
| In Zygote well-described body are absent. | In Foetus well-described body parts are present. |
18: Name some animals in which young ones are different from adult.
Answer: Silkworm and Frog have young ones different from adult.
19: Define asexual mode of reproduction.
Answer: Mode of reproduction in which only single parent is involved is called asexual reproduction.
20: Does all kind of asexual mode of reproduction can also be called Budding?
Answer: No, there is another mode of asexual reproduction apart from Budding, which is Binary fission.
21: Define Binary fission and give name of at least one organism following it.
Answer: The mode of asexual reproduction in which an animal reproduce itself by dividing into two individual is called Binary fission. Amoeba follows this mode for its reproduction.
22: Differentiate between Budding and Binary fission.
Answer: In Budding new organism develops from bud, whereas, in Binary fission organism reproduce by dividing itself into two.
23: Explain how chicks are born.
Answer: Chickens are not actually born, they are hatched from eggs. A chicken will ovulate and lay an egg within 24 hours. The chicken will continue to lay eggs every 24-36 hours. After eggs are layed, it takes about 3 weeks for them to hatch.
24: Name different stages of the lifecycle of a frog and silkworm.
Answer: Life cycle of frog: Eggs → Early tadpole → Late tadpole → Adult frog
Life cycle of a butterfly: Egg → Larva or caterpillar → pupa → Adult
25. What is reproduction? Explain its various modes.
Answer: The process by which organisms produce new offsprings of same species is called reproduction.
Modes of reproduction: There are following two modes of reproduction.
(i) Sexual reproduction: The method of reproduction in which two parents male, and female are involved is called reproduction.
(ii) Asexual reproduction: The method of reproduction in which only one parent (male or female) is involved is called asexual reproduction.
26. What are the male reproductive organs?
Answer: Male reproductive organs include a pair of testes, two sperm ducts and a penis. The testes produce the male gametes called sperm. Millions of sperms are produced by testes. The sperms are very small in size.
27. What is sperm? Explain its structure.
Answer: Sperm is a male reproductive cell. It is also called male gamete. There are mainly three parts of sperm:
(i) Head
(ii) Middle piece and
(iii) A long tail.
Indeed each sperm is a single cell with all the usual cell components.
28. What are the female reproductive organs?
Answer: The female reproductive organs are a pair of ovaries, oviducts (fallopian tubes) and a uterus. The ovary produces female gametes called ova or eggs. In human beings only one matured egg is released into oviduct by one of the ovaries every month. The development of baby takes place in uterus.
29. What is ovum? Explain its structure.
Answer: The female reproductive cell is called egg or ovum (plural ova). It is produced by ovaries. Like sperm, ovum is also a single cell and contains nucleus and other usual components.
30. What do you understand about test-tube baby?
Answer: Some women are unable to bear babies because sperms cannot reach the egg for fertilisation. In such cases, doctors collect freshly released egg and sperm and keep them together for few hours for IVF or in vitro fertilisation. In case fertilisation occurs the zygote is allowed to develop for a week and then it is placed in the mother’s uterus. Complete development takes place in the uterus and the baby is born like any other baby. Babies born through this technique are called test-tube babies.
31. Why is it necessary to produce large number of eggs and sperms by the animals which reproduce by external fertilisation?
Answer: The animals in which external fertilisation takes place produces a large number of eggs sperms. This is because the eggs and sperms get exposed to water movement, wind and rainfall. There are some other animals that may feed on eggs in the pond. Thus, production of large number of eggs and sperms is necessary to ensure fertilisation of at least a few of them.
32. How do chicks born?
Answer: After fertilisation the zygote divides repeatedly and travels down the oviduct. As it travels down, many protective layers are formed around it. The hard shell on the hen’s egg is one such protective layer. The hen finally lays egg. The embryo takes about three weeks to develop into a chick. After the chick is completely developed it bursts open the egg shell.
33. Explain the terms viviparous and oviparous with examples.
Answer: Viviparous: The animals which give birth to young ones are called viviparous animals. For example: cat, dog, cow and human beings.
Oviparous: The animals which lay eggs are called oviparous animals. In such animals development of embryo take place outside the female body. For example: All birds and reptiles.
34. Explain the life-cycle of silkworm in brief.
Answer: In silkworm, the young ones may look very different from the adults. We can write the life-cycle of a silkworm as follows:
Egg → Larva or caterpillar → Pupa → Adult.
The caterpillar or pupa of silkworm looks very different from the adult moth.
35. Explain the life-cycle of a frog.
Answer: There are three main stages in the life-cycle of a frog: (i) Egg (ii) Tadpole (larva) (iii) Adult. Tadpoles look different from the adults. After some time, these tadpoles are converted into adult frog.
36. What is asexual reproduction? Write various methods of asexual reproduction.
Answer: The type of reproduction in which only a single parent is involved is called asexual reproduction.
There are following methods of asexual reproduction:
(i) By budding
(ii) By binary fission
(iii) By vegetative reproduction.
37. Explain the asexual reproduction in amoeba.
Answer: The reproduction in amoeba takes place by binary fission. In this process amoeba reproduces by dividing into two individuals. The nucleus of amoeba cell is divided into two. This is followed by division of its body into two, each part receiving a nucleus. Finally, two amoebae are produced from one parent amoeba.
38. Explain Metamorphosis.
Answer: The transformation of larva into an adult through drastic changes is called metamorphosis. For example: The tadpole which develops from the eggs laid by the frog is entirely different from the frog. But when it grows, it becomes just like the frog. This drastic change in tadpole is called metamorphosis.
Long Answer Type Questions
1: Define metamorphosis. Explain it in human beings.
Answer: The transformation of the larva into an adult through drastic changes is called as metamorphosis. This is the matter of contradiction that human beings undergo metamorphosis or not. Some people say humans don’t go through metamorphosis. We just change size and appearance, but we are not considered to go through metamorphosis. On the other hand some people say Of course we go through metamorphosis! When you are born you are a big foot-long worm and as a young toddler you start to make a cocoon. Then, when you break out at about age 10 you are a normal looking person.
2: Define asexual reproduction. Describe two methods of asexual reproduction in animals.
Answer: Asexual reproduction is a type of reproduction where fertilization does not take place as only a single parent is involved. Offspring produced is identical to the parent because they are produced as clones. Types of asexual reproduction are as follows: fission, budding and fragmentation.
A. Fission: This type is mainly seen in unicellular prokaryotes. A full-grown organism at a certain stage splits into two identical daughter organisms.
B. Budding: In this type of asexual reproduction, a ‘bud’ or an outgrowth is formed on the mature adult body and eventually this bud separates and acts as an individual organism.
3: Why do frogs and fish lay eggs in hundred, whereas a hen lays only one egg at a time?
Answer: Organisms having internal fertilization like hen, produce one egg at a time. This is so because here there is less chance of failure of fusion between male and female gamete. After the gametes are fertilized there is just the need of development of animal in the form of egg.
Frog like aquatic organisms who shows external mode of reproduction have to lay egg in hundred. The first reason behind this is the single egg is so small in size that it will not be possible to stay to definite position and which in turns make hard for sperm to found and fuse them. Whereas, when large number of eggs make them stick together this makes fertilization possible. Another reason behind this is there is a lot of organisms who feed on these eggs, so larger number of eggs gives more possibility of giving birth to young ones.
4: Why frog lays egg coverless, whereas, Hen lays it with hard cover? Explain.
Answer: Hen reproduces through internal fertilization in which the egg is already fertilized before coming out as in form of egg.In the case of frog there is external fertilization, hence, egg fertilizes outside the female body. Female lays coverless eggs in the water body later male deposit there sperm over them. And with the help of tail, the sperm swims and fuses with egg. If these eggs have hard covering then it is impossible for the sperm to fuse with them and thus the reproduction cannot be possible.
5: Explain the importance of reproduction in organisms.
Answer: Reproduction is a process which is essential to maintain the life of an individual.
The organisms reproduce because of the two main reasons: –
- To continue one’s progeny
- It provides group immortality by replacing the dead individuals with the new ones for the survival of the species on this earth.
6: Explain cloning with an example of first cloned animal.
Answer: Cloning is defined as the production of exact copy of a cell, any other living part or a complete organism. Cloning of an animal was first of all performed successfully by Lan Wilmut and his colleagues, for the first time a sheep named as dolly was cloned successfully; Dolly was born on 5 July 1996 and was the first mammal to be cloned. The process of cloning involve collection of cell from the mammary gland of a female Finn Dorsett sheep and an egg whose nucleus was removed was obtained from a Scottish blackface ewe then nucleus from the mammary gland of Finn Dorsett sheep was inserted into egg of Scottish blackface ewe, the egg thus produced was implanted into the Scottish blackface ewe, development of this egg take place normally and finally Dolly was produced.
7: What do you mean by reproduction? Explain various modes of reproduction.
Answer: The process of producing young ones of the same species is known as reproduction. It is very important process. It helps in the continuation of a species on the earth.
Modes of Reproduction: There are following modes of reproduction:
(i) Sexual reproduction
(ii) Asexual reproduction.
(i) Sexual reproduction: The process of reproduction in which two parents (male and female) are involved is called sexual reproduction. In this process male produces male gametes and female produces female gametes. Both the gametes are fused to form zygote. The zygote develops into baby. Example: cow, cat, dog and human beings.
(ii) Asexual reproduction: The mode of reproduction in which only one parent is involved to produce new young ones is called asexual reproduction. Budding, fragmentation spore formation and binary fission are the methods of asexual reproduction like in hydra, amoeba and bacteria etc.
8: What is fertilisation? Explain various types of fertilisation.
Answer: When sperms come in contact of an egg, one of the sperms may fuse with the egg. Such type of fusion of sperm and egg is called fertilisation. In this process formation of zygote takes place. There are following two types of fertilisation:
(i) Internal fertilisation
(ii) External fertilisation.
(i) Internal fertilisation: The fertilisation in which fusion of egg and sperm takes place inside the body of female is called internal fertilisation. Internal fertilisation takes place in many animals like, cow, dogs, hens and human beings.
(ii) External fertilisation: The fertilisation in which fusion of egg and sperm takes place outside the body of female is called external fertilisation. It is very common in aquatic animals like fish, frog and starfish etc.
9: Explain the fertilisation in frog.
Answer: In frogs external fertilisation takes place. During rainy season frogs move to ponds and slow-flowing streams. When the male and female frog come together in water, the female lays hundreds of eggs. The eggs of frog are not covered by a shell and they are comparatively very delicate. A layer of jelly holds the eggs together and provides protection to the eggs. As the eggs are laid, the male deposits sperms over them. Each sperm swims randomly in water with the help of its tail. The sperms come in contact with eggs and fuse together. This results in fertilisation
10: Explain the development of embryo.
Answer: Fertilisation results in the formation of zygote which begins to develop into an embryo. The zygote divides repeatedly to give rise to a ball of cells. The cells then begin to form groups that develop into different tissues and organs of the body. This developing structure is termed as embryo. This embryo gets embedded in the wall of the uterus for further development. The embryo continues to develop in the uterus. It gradually develops body parts such as hands, legs, head, eyes and ears etc. This stage is called foetus. Mother gives birth to the baby when foetus developed completely.
Fig. (a) Zygote formation and development of an embryo from the zygote; (b) Ball of cells (enlarged); (c) Embedding of the embryo in the uterus (enlarged).
11: Explain the formation of clone Dolly.
Answer: Cloning is the production of an exact copy of a cell, a part or complete body. Dolly was the first clone born on 5th July 1996 and was the first mammal to be cloned. It is cloned by Ian Wilmut and his colleagues. During the process of cloning Dolly, a cell was collected from the mammary gland of female Finn Dorsett sheep.
Fig. (a) Finn Dorsett sheep (b) Scottish blackface ewe (c) Dolly (July 1996 to Feb. 2003).
Simultaneously, an egg was obtained from a Scottish blackface ewe. The nucleus was removed from the egg, then the nucleus of mammary gland cell from the Finn Dorsett sheep was inserted into egg of Scottish blackface ewe. Development of this egg followed normally and finally Dolly was born. It was found to be absolutely identical to the Finn Dorsett sheep and produced several offspring of her own through normal sexual means. Dolly died on 14th February 2003 due to a certain lung disease
12: What are Sexually Transmitted Diseases? How can they be prevented?
Answer: The diseases spread only by sexual contact are called sexually transmitted diseases (STDs). When a healthy person contacts sexually to a person which is infected, then the microorganisms are transmitted from infected person to the healthy person and that becomes infected. Syphilis, gonorrhoea, herpes and AIDS are some sexually transmitted diseases. Herpes and AIDS are not curable diseases. These are fatal diseases, which destroy the immune system of the patient. Sexual hygiene and safe sexual relationship are the only way to prevent sexually transmitted diseases.