NCERT Exemplar Solution Class 8 Science Chapter 9
NCERT Exemplar Solution Class 8 Science Chapter 9 Reproduction in Animals all Questions Answer Solution. NCERT Exemplar Class 8 Science Chapter 9 Solution PDF.
NCERT Exemplar Solution Class 8 Science Chapter 9: Overview
NCERT Exemplar Solution Class 8 Science Chapter 9 |
|
Board |
NCERT |
Topic |
Exemplar Problem Solution |
Class |
8 |
Subject |
Science |
Chapter |
9 |
Chapter Name |
Reproduction in Animals |
NCERT Exemplar Solution Class 8 Science Chapter 9 Reproduction in Animals
Multiple Choice Questions
1) 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
Answer:- c) sperm, Oviduct, egg, uterus
These is an incorrect set. These includes both male and female reproductive parts. Other has only male or female reproductive terms.
2) In humans, the development of fertilised egg takes place in the
a) Ovary
b) Testis
c) Oviduct
d) Uterus
Answer:- d) Uterus.
Uterus is the part of female reproductive system where the eggs fertilisation takes place.
3) In the list of animals given below, hen is the odd one out.
Humans 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.
Answer:- b) it is Oviparous
Hen is oviparous that is it does not give direct birth to the cheeks, but lays eggs. Other gives directly birth to their child.
4) 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 offspring.
b) Food is available in plenty in water.
c) To ensure better chance of fertilisation.
d) Water promotes production of large number of gametes.
Answer:- c) To ensure better chance of fertilisation.
Large number of Gametes are produced during external Fertilisation to ensure the maximum chance of the Fertilisation. These type of Fertilisation is occurs in most of the aquatic animals like fishes and toad, frogs etc.
5) Reproduction by budding takes place in
a) Hydra
b) Amoeba
c) Paramecium
d) Bacteria
Answer:- a) Hydra
Hydra does not reproduce by any other methods. It is reproduced through producing buds and the process is called budding. Amoeba, paramecium and bacteria reproduce by another reproduction methods.
6) Which of the following statements about reproduction in humans is correct?
a) Fertilisation takes place externally.
b) Fertilisation takes place in the testes.
c) During fertilisation egg moves towards the sperm.
d) Fertilisation takes place in the human female.
Answer:- d) Fertilisation takes place in the human female.
Fertilisation takes place in human females. These is an sexual reproduction which takes place internally.
7) In human beings, after fertilisation, the structure which gets embedded in the wall of uterus is
a) Ovum
b) Embryo
c) Foetus
d) Zygote
Answer:- b) Embryo
After Fertilisation a single celled egg i.e. zygote is produced. Which is further formed into embryo and embedded on the wall of the uterus for
8) Aquatic animals in which fertilisation occurs in water are said to be :
a) Viviparous without fertilisation.
b) Oviparous with external fertilisation.
c) Viviparous with internal fertilisation.
d) Oviparous with internal fertilisation.
Answer:- b) Oviparous with external fertilisation.
Aquatic animals are oviparous they lay eggs but their Fertilisation is external i.e. Fertilisation occur outside the body.
9) After fertilisation, the resulting cell which Zygote rise to a new individual is the
a) Embryo
b) Ovum
c) Foetus
d) Zygote
Answer:- d) Zygote
During Fertilisation male and female zygote fuses together to form a single celled Fertilised zygote. Then it turns into embryo and further into foetus.
10) In human beings, the correct sequence of events during reproduction is
a) Gamete formation, fertilisation, zygote, embryo.
b) Embryo, zygote , fertilisation, gamete formation.
c) Fertilisation, gamete formation, embryo, zygote.
d) Gamete formation, fertilisation, embryo, zygote
Answer:- a) Gamete formation, fertilisation, zygote, embryo
Reproduction occurs in the sequence like gamete formation then Fertilisation then zygote formation and finally embryo.
Very Short Answer Questions
11) Although 2 cells called gametes fuse, the product formed is a single cell called zygote. Justify.
Answer:- Fertilisation is the process in which two cells i.e. male gamete sperm and female gamete ovumfuses together and form a single celled zygote. The fusion of these two cells occurs a new single fertilised egg i.e. zygote is formed.
12) Stages in the lifecycle of Silkworm are given below. Write them in sequential order.
Pupa, Silkworm, egg, silk moth
Answer:-
The sequential order of the stages in the lifecycle of Silkworm is-
Egg, caterpillar, pupa, silk moth
The complete stages of life cycle of Silk moth.
13) What is the importance of reproduction?
Answer:-reproduction is important for the life. Reproduction of the same type of individuals is necessary for the continuation of life. Reproduction also plays an important role in the carrying the genetic information from generation to generation.
14) In markets, egg of birds are available but never eggs of dogs. Why?
Answer:- birds are oviparous. They lay eggsand do not give direct birth to the young once. But dogs are viviparous i.e. they gives directly birth to the young once. Therefore dogs egg are not available in market.
15) The eggs of frogs do not have shells for protection, yet they are safe in water. How?
Answer:- Yes, eggs of the frog do not have hard shells like other animals. But eggs are covered with a layer of jelly holds all the eggs together and thus provides protection to the eggs. Therefore while floating in the water these eggs are safe due to jelly layer.
Short Answer Questions
16) Fill up the blanks with the terms given below:
Body, asexual, binary, single, nucleus
Amoeba is a _______ celled organism. It reproduces by __________ reproduction. The process of reproduction begins by the division of its _________ into two_____.This type of reproduction is called _______ fission.
Answer:-
Amoeba is a single celled organism. It reproduces by Asexual reproduction. The process of reproduction begins by the division of its nucleus into two body. This type of reproduction is called binary fission.
17) The term metamorphosis is not used while describing human development. Why?
Answer:- The term metamorphosis leads to the drastic change i.e. sudden change in which the transformation of the larva into an adult takes place. But in the human body all the body parts are present from the birth, similar to the adult human beings.
18) Mother gives birth to a baby but the baby has characters of both parents. How is this possible?
Answer:-
During fertilisation both the male and female fuses together to form a single celled zygote. These process is the meeting of an egg cells from the male andsperm cells from Female. Therefore the new individual has the characters of both the mother and father. As both Gametes contains hereditary characters.
19) How is Reproduction in hydra different from that in Amoeba?
Answer:-
The Reproduction in the hydra is different from Amoeba.
Hydra reproduce by the process of budding and amoeba reproduce by the process of binary fission. These are the type of asexual reproduction in which only one parent is involved.
The process of reproduction in hydra – (Budding)
Hydra produces buds On its body. these buds are outgrowth of the parent body.
These buds after maturation get separated from the parents body and thus forms a new individual. These process is called as Budding.
The process of reproduction in Amoeba- (Binary fission)
Reproduction in the amoeba takes place through binary fission. In these process, An single celled Amoeba divide its nucleus into two daughter nuclei. After that there is division of its body into two similar parts. Both the divided parts contains nucleus. After these process two daughter Amoeba are produced from the single amoeba.
These both processes are of asexual type of reproduction but hydra and amoeba reproduce by two different processes.
20) State whether the following statements are True or False. If false, correct the Statement.
a) External fertilisation can occur both in water and on land.
Answer:- False
External fertilisation can occur only in water and not on land.
b) The eggs of fish are covered by hard shells for protection.
Answer :- False
The eggs of fish are covered by the soft jelly for protection.
c) Human eggs has a head, middle piece and tail.
Answer:- false
Human mail’s sperm has a head, middle piece and tail.
d) In adult human females, a single mature egg is released into an oviduct every month.
Answer:- True
21) Why do only male gametes have a tail?
Answer:-
During the Fertilisation process both the male and female gametes should be come in contact with each other. But Female eggs are non motile. Therefore sperm should be motile. Sperm has the three parts head, middle piece and tail. These tail helps sperms to move further I’m the Female reproductive parts. And thus the sperm reaches to the egg cells and fertilisation occurs.
22) What does fig. 9.1 represent?
Fig. 9.1
Answer:-
Figure shows the process of binary fissions by the amoeba. Amoeba reproduce by binary fission with single parent. These is an asexual type of reproduction, in which they divide into two body along with nuclei. And form an another individual from a single body.
23) Observe the figure given as fig. 9.2 and Answer the questions that follow.
Fig. 9.2
a) Label A and B.
Answer:- A- sperm
B- Ovum
b) Identify the process.
Answer:- the process in the given figure is fertilisation.
c) What happens during this process and what is formed?
Answer:- During the process of Fertilisation the formation of single celled fertilised egg i.e zygote takes place, when the sperm cells and egg cells are fuses together .
Long Answer Questions
24) How can we say that fish exhibits external fertilisation?
Answer:- Fishes, frogs and other aquatic animals perform external Fertilisation.
During the rainy season, the male fish and female fish comes together in the water. Female lays eggs over there,(about hundreds to ensure the Fertilisation) . These eggs are covered with jelly layer which protects the eggs floating in water. Further the male fish deposit sperms over the eggs. The male sperms swims in water and as soon as they comes in contact with the eggs it results in fertilisation.
It is known as external fertilisation because the Fertilisation of the male and female Gametes takes place outside of the female body.
25)
FIG. 9.3
After observing fig. 9.3 Answer the following.
(a) Read the following statements and label them in the figure.
(i) The part which produces female gametes.
Answer:- ovary
ii) the part where development of the body takes place.
Answer:-uterus
iii) the part through which the developing embryo passes to reach the uterus.
Answer:- oviduct
b) Explain the future development of the embryo that would takes place after it gets embedded in the uterus.
Answer:-
Embryo formation takes place through the zygote. Zygote multiplies its cells in number and forms a ball like structure. These cells begin to develop and form groups which further develops into different tissues and organs of body part. These structure which is developing is known as embryo. These embryo get embedded on the wall of uterus. And further development of these embryo takes place in the uterus. These embryo developed into the body parts like, legs, hand, head, eyes etc. When all the body parts are identified then the structure is called as foetus. These foetus continue the development and finally mother gives birth to baby.
26) Hens and frogs are both oviparous exhibiting different types of fertilisation. Explain.
Answer:- Hens and frogs both are oviparous both lays eggs but the mode of Fertilisation is different. Hens perform the internal Fertilisation while the frogs perform external Fertilisation. Internal Fertilisation is in which the Fertilisation takes place inside the Female’s body. And external Fertilisation is in which the Fertilisation takes place outside the Female’s body.
Hens perform the internal Fertilisation. A fertilised egg develops into embryo and then development of chick takes place inside the body.
Frogs perform external Fertilisation by spreading male gametes and female gametes in the water . Male sperm reaches female eggs by swimming in the water and thus Fertilisation takes place outside the body.
27) Observe the following figures.
a)
i) Identify the stages a to d in fig. 9.4 during development of human baby.
b)
Answer:- figure A shows the embryo embedded into the wall of uterus.
c)
Answer:- Figure B shows Fertilisation process.
d)
Answer:- figure C shows the formation of zygote and development of embryo from the zygote.
e) Answer:- figure D shows the fusion of nuclei into the zygote.
ii) Arrange the stages in correct sequence of development.
Answer:-
The correct sequence of stages of development according to the given figures are –
1) C- formation of zygote and development of embryo from that zygote.
2) B- Fertilisation process
3) D- fusion of nuclei into the zygote.
4) A- embryo embedded into the wall of uterus.
iii) explain the development that takes place in any one stage.
Answer:-
Embryo embedded in the wall of uterus:-
After Fertilisation the formation of zygote takes place, which is further develops into embryo. There is repeated division of cells of zygote occurs. It give rise to a ball like structure. These cells begin to develop into tissues and organs of the body part. And these developing structure is called as embryo. These embryo is embedded on the wall of the uterus for further development into a foetus.