Reproduction in Animals Class 8 Extra Questions Science Chapter 9
Reproduction in Animals Class 8 Extra Questions Very Short Answer Questions
What is reproduction?
Reproduction is the biological process by which new individual organisms are produced from their parents.
What is sexual reproduction?
Reproduction which involves the fusion of male and female gametes is known as sexual reproduction.
What is fertilisation?
The fusion of ova and sperm is called fertilisation.
What is a fertilised egg called?
What is asexual reproduction?
The mode of reproduction in which only a single parent is involved.
Which mode of reproduction does take place in human beings?
How many partners involve in sexual reproduction?
Name two animals in which asexual reproduction takes place.
Hydra and yeast
Name the reproductive organs of male.
A pair of testes, two spermducts and a penis.
Name the reproductive organs of female.
A pair of ovaries, oviducts and uterus.
Name the modes of reproduction.
- Sexual reproduction
- Asexual reproduction.
What is male gamete or sperm?
The reproductive cell produced by male reproductive organs is called male gamete or sperm.
What is female gamete or ova?
The reproductive cell produced by female reproductive organs is called female gamete or ova.
Which organ produces eggs or ovum?
A pair of ovary.
Name the male gamete.
Name the female gamete.
Ova or egg
Which male reproductive organ produces sperm?
A pair of testes.
In which organ fertilisation take place in female?
What are the two methods of asexual reproduction?
- Binary fission
Name two animals which undergo external fertilisation.
Frog and fish
Name two animals which undergo internal fertilisation.
Human being and cow
Which type of reproduction takes place in Amoeba?
Asexual reproduction through binary fission.
What type of reproduction is cloning?
What is foetus?
Foetus is a well developed embryo.
What is IVF technique of reproduction?
It is fertilisation outside the body.
Give the full form of IVF.
In vitro Fertilisation.
How are test tube babies born?
Test tube babies are born through IVF technique.
What is cloning?
Cloning is the production of exact copy of a part of or whole living body.
Reproduction in Animals Class 8 Extra Questions Short Answer Questions
Explain two modes of reproduction with examples.
There are two modes of reproduction:
- Sexual reproduction: This type of reproduction takes place by fusion of male and female gametes; e.g., Human beings, mammals like cow, buffalo, etc.
- Asexual reproduction: This mode of reproduction involves only a single parent; e.g., Hydra, Amoeba, yeast, etc.
Explain the process of fertilisation in brief.
Fusion of the male and female gamete, i.e., sperm and egg is called fertilisation. During fertilisation, the nuclei of the sperm and the egg fuse to form a single nucleus resulting in the formation of a fertilised egg or zygote.
What is internal fertilisation? Explain briefly.
Fertilisation which takes place inside the female body is called internal fertilisation. In this a smaller number of ova or eggs are produced. Offsprings have high chance of survival. It occurs mostly in mam¬mals; e.g., in human being, cow, buffalo, etc.
Explain briefly the external fertilisation.
In external fertilisation, fusion of male and female gametes take place outside the female body. The female discharge many eggs in the water and the male discharge sperms. The sperms swim to the eggs and fertilise them. It occurs in most of the aquatic animals like frog, fish, starfish, etc.
How is an embryo developed?
Fertilisation results in the formation of zygote. The zygote divides repeatedly to give rise to a ball of cells which then begin to form groups that develop into different tissues and organs of the body. This developing structure is called an embryo. It gets embedded in the wall of the uterus for further development.
Explain what is foetus.
The embryo continues to develop in the uterus. It gradually develops different body parts such as hands, legs, head, eyes, etc. The stage of the embryo in which all the body parts can be identified is called a foetus. After its development is complete, the mother gives birth to the baby.
What are viviparous and oviparous animals?
The animals which give birth to young ones are called viviparous animals and those which lay eggs are called oviparous animals. For example, Mammals including human beings are viviparous animals and hen, lizards, all birds, etc., are oviparous animals.
What are sperm and ovum? Explain.
The male gamete is called sperm. It is produced by male reproductive organ, testes. Structurally, it consists of a head attached to a long tail. The tail helps the sperm to move around. The head bears the small nucleus.
Ovum are the female gamete. They are also called egg. They are produced by the female reproductive organ. They consist of larger nucleus.
Both sperm and ovum are reproductive cells and contain single cell.
Explain briefly the life cycle of a frog.
There are mainly three distinct stages in the life cycle of a frog, i.e., egg → tadpole (larva) → adult. Tadpoles look different from the adults. After sometime tadpoles are converted into an adult frog.
Explain in short life cycle of silkworm.
The life cycle of silkworm is completed in four stages.
Egg → Larva or Caterpillar → Pupa → Adult
In silkworm the caterpillar or pupa looks very different from the adult moth.
Reproduction in Animals Class 8 Extra Questions Long Answer Questions
What do you mean by reproduction? Describe various modes of reproduction.
Reproduction is an important process which is responsible for the continuity of life on the planet earth. In this process, an individual produces young ones of the same species. It helps in increasing the population of the same species on the earth, generation after generation. This is the fundamental feature which ensures the existence of all life forms on the earth. There are two modes of reproduction:
- Sexual reproduction: In this type of reproduction, both male and female parents are involved and they produce different gametes called male gametes or sperms and female gametes or ova (egg) respectively. Both fuse to form zygote which finally develops into foetus. For example, mammals including human beings higher invertebrates and all vertebrates undergo sexual reproduction.
- Asexual reproduction: In this type of reproduction, only single parent is involved and gametes or sex cells are not produced. Budding, binary fission, etc., are different methods of asexual reproduc¬tion. Lower organisms like Hydra, Amoeba, yeast, etc., undergo asexual reproduction.
What do you mean by metamorphosis? How does metamorphosis take place in frog? Explain with a diagram.
The transformation of the larva into an adult through drastic (sudden or abrupt) changes is called metamorphosis. For example, a moth emerging out of the cocoon, an adult frog from a tadpole, etc., undergo metamorphosis.
Frog undergoes through three stages during its life cycle in which eggs laid down by frogs transform into tadpoles (larva) and finally into an adult following the process of metamorphosis. The following diagram clearly shows this process.
Describe the male reproductive organs with the help of a labelled diagram.
The male reproductive organs mainly consist of a pair of testes, two sperm ducts (vas deferens) and a penis. Male gametes called sperms are produced by the testes. Though the sperms are very small in size, each has a head, a middle piece and a tail. It is unicelled with all the usual cell components. Figure 9.14 shows the male reproductive organs in humans.
Describe female reproductive organs with the help of a labelled diagram.
The female reproductive organs mainly consist of a pair of ovaries, oviducts or fallopian tubes, uterus and vagina. The female gametes called ova or eggs are produced by ovary. In human beings, a single matured egg is released into the oviduct by one of the ovaries every month. Uterus is the part inside which the embryo grows and develops finally into a baby. An egg or ovum is a single cell. Vagina is the part which receives the penis during copulation. The following diagram shows these organs clearly.
Explain with a diagram the development of an embryo.
An embryo is developed in the process of fertilisation. Fertilisation results in the formation of zygote which begins to develop into an embryo [Refer Fig. 9.7(a)].
The zygote divides repeatedly to give rise to a ball of cell (Refer Fig. 9.7(b)) which further begin to form groups that develop into different tissues and organs of the body. This developing structure is called an embryo. The embryo gets embedded in the wall of the uterus for further development [Refer Fig. 9.7(c)]. The embryo continues to develop in the uterus. It gradually develops different body parts. This developing stage of embryo is called foetu (Fig. 9.16).
What is cloning? Explain how first cloned mammal was born.
Cloning is the production of an exact or a true copy of a cell, any other living part, or a complete organ¬ism by asexual reproduction. Cloning of an animal was successfully performed for the first time by Ian Wilmut and his colleagues at the Roslin Institute in Edinburgh, Scotland. They cloned the sheep named Dolly on July 5, 1996.
In the process of cloning Dolly, a cell was collected from the mammary gland of a female Finn Dorsett sheep [Fig. 9.17(a)]. Meanwhile, an egg was obtained from a Scottish blackface ewe [Fig. 9.17(b)]. The nucleus was removed from the egg. Then, the nucleus of the mammary gland cell from the Finn Dorsett sheep was inserted into the egg of the Scottish blackface ewe whose nucleus had been removed. This egg was implanted into the Scottish blackface ewe. The egg developed normally and finally Dolly was born. Cloning of Dolly was a successful attempt. However, many clones often die soon after birth. Sometimes cloning also leads to certain abnormalities among clones. Unfortunately, Dolly died on 14th February, 2003 due to a certain lung disease.
What is budding? Explain.
Budding is type of asexual reproduction in which an organism or new individual develops from an outgrowth from a single parent. This outgrowth is called bud. On maturation this bud get separated from the parent’s body to grow into new individual. This process of reproduction is known as budding. For example, Hydra, yeast and sponges produce their young ones through the process of budding. In some organisms, like sponges, buds are not separated from their parent’s body and form a colony. They remain attached to parent’s body.
Explain how Amoeba reproduce?
Explain in brief the process of binary fission.
Amoeba reproduces through the process of binary fission. Binary fission is another method of asexual reproduction. Amoeba is a single-celled organism. It begins the process of reproduction by the division of its nucleus into two nuclei followed by division of its body into two, each part receiving a nucleus. Finally two daughter cells are produced from one parent Amoeba. This type of asexual reproduction in which an animal reproduces by dividing into two individuals is known as binary fission.
What is metamorphosis? Explain.
Some insects and animals undergo a series of changes after birth. Their young ones look quite different from them. The features of these young ones are completely different from the adults. A biological process in which larva transforms into an adult through drastic changes (sudden and abrupt changes) in the body of the animal during the life cycle of an invertebrate or amphibian is called metamorphosis. For example, frog, butterfly, etc., undergo metamorphosis.
How are babies produced through IVF technique? What are such babies called?
IVF (In Vitro Fertilisation), is an artificial type of fertilisation. Some women’s oviducts are blocked and so they cannot bear babies because sperms cannot reach the egg for fertilisation. In such cases, freshly released eggs and sperms are kept together for a few hours for IVF (fertilisation outside the body). In case fertilisation occurs, zygote thus formed is allowed to develop for a week and then it is placed in the mother’s uterus. Complete development of baby occurs in uterus and is born like any other baby. Babies born through this technique are called test tube babies.
Reproduction in Animals Class 8 Extra Questions Higher Order Thinking Skills
Although two cells called gamete fuse, the product formed is a single cell called zygote. Justify.
During fertilisation, only the male nucleus moves into the egg cell and fuses to the egg nucleus to form zygote which is thus a single cell. The sperm remain outside the egg cell and degenerates after some time.
The eggs of frogs do not have shells for protection, yet they are safe in water. How?
A layer of jelly covers the eggs of frog and provides protection. Water help them to float and retain moisture. If eggs are laid in land then they will dry up and die.
Mother gives birth to a baby but the baby has characters of both parents. How?
Human beings show sexual reproduction. During fertilisation, two gametes, one from the mother and the other from father, fuse together to form zygote. Therefore baby developed from zygote has characters of both parents though mother gives birth to a baby.
Why do only male gametes have a tail?
Male gametes have to reach non-motile female gamete in oviduct from the vagina. So they have a tail to reach the egg cell.
Though hen and frog both are oviparous but they have different types of fertilisation. Justify.
In hen, internal fertilisation takes place. The fertilised egg develops into an embryo inside the body. But development of chick from the embryo takes place outside the body. On the other hand, frog shows external fertilisation. The female frog discharge many eggs in the water and the male frog discharge sperms. The sperms swim to the eggs and fertilise them.
How does twinning occurs during sexual reproduction?
Twins are two offspring produced by same pregnancy. Non-identical twins results from two fertilised eggs when get implanted in the uterus wall at the same time.
Identical twins occur when a single egg is fertilised to form one zygote which then divides into two separate embryos.
Reproduction in Animals Class 8 Extra Questions Value-Based Questions
Ram with his family went to a picnic spot near a pond. He saw some jelly-like mass floating on the sides of the pond. He asked about this to his father. His father explained him that these are frog’s egg and are millions in number. Ram wondered if all of them get hatched, what will happen to other aquatic animals?
- What type of fertilisation is shown by frog?
- Why do frog lay eggs in large amount?
- Is Ram’s concern about hatching of too many eggs at a time will affect the aquatic animals correct? Why?
- What Value of Ram is shown here?
- Frog shows external fertilisation.
- Mortality rate is very high for tadpoles as their predators are more. Many of the eggs do not develop due to being not get fertilised. So for continuation of their species, they lay egg in large amount.
- No, his concern is not correct because most of the eggs either never develops or are preyed by other animals. So survival chance of a frog from its egg to an adult frog is very low.
- Ram is inquisitive, future thinker and eco-concerned.
Activities and Projects
Visit a poultry farm. Talk to the manager of the farm and try to find out the answers to the following.
- What are layers and broilers in a poultry farm?
- Do hens lay unfertilised eggs?
- How can you obtain fertilised and unfertilised eggs?
- Are the eggs that we get in the stores fertilised or unfertilised?
- Can you consume fertilised eggs?
- Is there any difference in the nutritional value of fertilised and unfertilised eggs?
Visit a poultry farm, you can get answers to these questions. However, answers are given here for your help.
- Hens which lay eggs are layers and broilers are the hens used to get meat.
- Yes. Though hens lay fertilised eggs but in the poultry farms, the unfertilised eggs are obtained by induced ovulation.
- We can obtain fertilised eggs by normal procedure whereas unfertilised eggs can be obtained by induced ovulation in a poultry farm.
- Both types of eggs are available at stores.
- Yes, fertilised eggs have more nutritional value.
Observe live Hydra yourself and learn how they reproduce by doing the following activity: During the summer months collect water weeds from ponds or ditches along with the pond water and put them in a glass jar. After a day or so you may see several Hydra clinging to the sides of the jar.
Hydra is transparent, jelly-like and with tentacles. It clings to the jar with the base of its body. If the jar is shaken, the Hydra will contract instantly into a small blob, at the same time drawing its tentacles in.
Now take out few Hydras from the jar and put them on a watch glass. Using a hand lens or a binocular or dissection microscope, observe the changes that are taking place in their body. Note down your observations.
Do it yourself.
The eggs we get from the market are generally the unfertilised ones. In case you wish to observe a developing chick embryo, get a fertilised egg from the poultry or hatchery which has been incubated for 36 hours or more. You may then be able to see a white disc-like struc¬ture on the yolk. This is the developing embryo. Sometimes if the heart and blood vessels have developed you may even see a red spot.
Do it yourself at home.
Talk to a doctor. Find out how twinning occurs. Look for any twins in your neighbourhood, or among your friends. Find out if the twins are identical or non-identical. Also find out why identical twins are always of the same sex? If you know of any story about twins, write it in your own words. You could visit the following websites for information on twins: www. keepkidshealthy.com/twins/expecting_twins.html.
For more information on animal reproduction, you can visit:
Twinning means producing two offspring at a time. It occurs in two ways:
- Two ova or eggs (female gametes) are released during ovulation and get fertilised.
- Single fertilised egg or ovum undergoes fission giving rise to two foetus.
In first case, twins are unidentical or unsimilar whereas in second case, they are identical or similar. Since identical twins are born from same egg (ova) and sperm, i.e., same female and male gametes, they always have same sex.
Students are advised to find out all these practically in their neighbourhood with friends.
I. Multiple Choice Questions (MCQs)
Choose the correct option.
The number of modes by which animals reproduce are
(d) none of these
Binary fission is observed in
(d) human being
Asexual reproduction is observed in
In Hydra, the mode of reproduction is
(c) both (a) and (b)
(d) none of these
The animals that produce new young ones are called
(d) none of these
The male gamete or sperm consists of
(a) three parts
(b) two parts
(c) four parts
(d) none of these
Ovum or eggs are formed in
Internal fertilisation takes place
(a) inside male body
(b) inside female body
(c) outside female body
(d) outside male body
In humans, the development of fertilised egg takes place in the
The cell formed after fertilisation is called
The fusion of sperm and ova usually occur in the
Sets of reproductive terms are given below. Choose the set that has an incorrect combination.
(a) Sperm, testis, sperm duct, penis
(b) Menstruation, egg, oviduct, uterus
(c) Sperm, oviduct, egg, uterus
(d) Ovulation, egg, oviduct, uterus
Which of the following shows external fertilisation?
(b) Human being
Which one of the following is not a part of female reproductive organs?
In the list of animals given below, hen is the odd one out.
‘human being, cow, dog, hen’
The reason for this is
(a) it undergoes internal fertilisation
(b) it is oviparous
(c) it is viviparous
(d) it undergoes external fertilisation
Animals exhibiting external fertilisation produce a large number of gametes. Pick the appropriate reason from the following
(a) The animals are small in size and want to produce more offsprings.
(b) Food is available in plenty in water.
(c) To ensure better chance of fertilisation.
(d) Water promotes production of large number of gametes.
Which is not a viviparous animal?
(a) Human being
Budding occurs in
The female gamete is called
The male gamete is called
II. Fill in the Blanks
Fill in the blanks with suitable word/s.
1. __________ is the process that ensures continuity of life on earth.
2. __________ are the cells involved in sexual reproduction.
3. The animals which lay eggs are called __________.
4. The animals which give birth to young ones are called __________.
5. __________ is the process of fusion of gametes.
6. The process of reproduction involving fusion of male and female gametes is called __________ reproduction.
7. The testes produce the male gametes called __________.
8. Sperms are __________ in size.
9. Sperm is a __________ cell.
10. The female reproductive organ consists of __________, __________ and __________.
11. The ovary produces female gamete called __________.
12. An ova or egg is a __________ cell.
13. __________ is a fertilised egg.
14. Internal fertilisation takes place inside __________.
15. Babies born through __________ technique are called test tube babies.
16. __________ fertilisation takes place outside the female body.
17. Fertilisation results in the formation of __________ and __________.
18. All living organisms have the power to __________.
19. __________ produces sperm in male.
20. In __________ reproduction only a single parent is involved.
8. very small
10. ovaries, oviduct, uterus
11. ova (egg)
14. female body
17. zygote, embryo
III. Match the following
Match the items given in column I suitably with those given in column II.
IV. True or False
State whether the given statements are true or false.
1. Zygote is an unfertilised egg.
2. External fertilisation occurs in frog.
3. An embryo is made up of multicells.
4. Amoeba reproduces by budding.
5. Fertilisation is not necessary in asexual reproduction.
6. Each sperm is multicellular.
7. A new young one is developed from a cell called gamete.
8. Cloning is a sexual reproduction method in any living organisms.
9. Viviparous animals give birth to young ones.
10. Male gametes are sperms.
11. Female gametes are ovum.
12. Starfish reproduces by external fertilisation.
13. Two individuals are needed for sexual reproduction.
14. Internal fertilisation occurs in dogs and cats.
15. An embryo grows in uterus.