Question 1. Explain the importance of reproduction in organism.
Solution : The production of new individual form the parents is known as reproduction. Reproduction is very important as it ensures the continuation of similar kinds of individuals, generation after generation. If this process do not exist, the generation of living beings will be vanished from the earth.
Question 2. Describe the process of fertilisation in human beings.
Solution : In human beings, sexual reproduction occurs in which reproduction results from the fusion of male and female gametes. Male produce sperms in testes and female produce ovum in ovary. Male release their sperms in female reproductive organ during copulation, called vagina from where the sperms move towards the fallopian tube. Female release one ovum every month in the middle of menstruation cycle which travels towards the fallopian tube. The fusion of male and female gametes takes place in fallopian tube. The fusion of male and female gametes is called fertilisation.
Question 3. Choose the most appropriate answer.
(a) Internal fertilisation occurs
i. In female body.
ii. Outside female body
iii. In male body
iv. Outside male body
(b) A tadpole develops into an adult frog by the process of
i. Fertilisation.
ii. Metamorphosis
iii. Embedding
iv. Budding
(c) The number of nuclei present in a zygote is
i. None
ii. One
iii. Two
iv. Four
Solution :
(a) (i)in female body.
(b) (ii)metamorphosis.
(c) (ii)one.
Question 4. Indicate whether the following statements are True (T) or False (F).
(a)Oviparous animals give birth to young one. ( ).
(b)Each sperm is a single cell. ( ).
(c)External fertilisation takes place in frog. ( ).
(d)A new human individual develops from a cell called gamete.( ).
(e)Egg laid after fertilisation is made up of a single cell. ( ).
(f)Amoeba reproduces by budding. ( ).
(g)Fertilisation is necessary even in asexual reproduction.( ).
(h) Binary fission is a method of asexual reproduction.( ).
(i) A zygote is formed as a result of fertilisation.( ).
(j) An embryo is made up of a single cell. ( ).
Solution :
(a) False
(b) True
(c) True
(d) False
(e) True
(f) False
(g) False
(h) True
(i) True
(j) False
Question 5. Give two differences between a zygote and Foetus
Solution :
| Zygote | Foetus |
| (i) It is fertilized egg formed after the fusion of the sperm with the egg. | (i) It is a stage of the embryo that shows all the main recognizable body parts of a mature organism. |
| (ii) The zygote divides several times to form an embryo. | (ii) An embryo gradually develops into a foetus. |
Question 6.Define asexual reproduction. Describe two methods of asexual reproduction in animals.
Solution : Asexual reproduction is a mode of reproduction that does not involve tile fusion of the male and the female gametes. It requires only one parent, and the offsprings produced are exact copies of their parents.
Two methods of asexual reproduction in animals are:
(i) Binary fission: It is a type of asexual reproduction in which a single cell divides into two halves, Organisms that reproduce through binary fission are bacteria and Amoeba. In Amoeba, the division of cells can take place in any plane. It involves the division of its nucleus into two nuclei, which is followed by the division of its body into two halves, Each half of the body receives a nucleus.
Fig: Binary fission in Amoeba
(ii) Budding: Budding involves the formation of a new individual from the bulges, known as buds formed on the parent body, This method of reproduction is common in Hydra, In Hydra, the cells divide rapidly at a specific site and develop as an outgrowth, called the bud. These buds, while being attached to the parent plant, develop into smaller individuals. When these individuals become mature enough, they detach from the parent’s body and become independent individuals.
Fig: Budding in Yeast
Question 7. In which female reproductive organ does the embryo get embedded?
Solution : In the female reproductive organ, the embryo gets attached to the uterus. Once it gets attached, there occurs formation of body parts like legs, hands, eyes etc.
The embryo is then called as a fetus.
Question 8. Explain the term metamorphosis. State examples.
Solution : It is defined as the process in which an animal’s body structure abruptly changes through cell growth and differentiation.
It is a biological process.
Examples of this kind are frog and insects.
Life cycle of a frog:
The tadpole emerging from the egg will have gills ,tail etc.
They can swim easily in water.
It undergoes abrupt changes and develops into a mature frog.
Question 9. Explain the difference between internal fertilization and external fertilization.
Solution :
| Internal fertilization | External fertilization |
| It involves the fusion of the male and the female gamete inside the female body. | It involves the fusion of the male and the female gamete outside the female body. |
| Chances of the survival of the offspring are more. Therefore, a small number of eggs are produced. | Chances of survival of the offspring are less. Therefore, a large number of eggs are produced. |
| Humans, cows, hens are organisms showing internal fertilization. | Fish, frog, starfish are organisms showing external fertilization. |
Question 10. Solve the crossword puzzle using hints given below.
Across:
1.Fusion of male and female gametes
6.Fertilization in human
7.The new part developed in the side body of the hydra
8.Female gamete
Down:
2.Place where sperm and testosterone are produced
3.Fertilized egg is also known as
4.Animals that reproduce by laying eggs
5.What type of process takes place in amoeba?
Solution :
Across:
1.Fertilization
6.Internal
7.Buds
8.Ovary
Down:
2.Testis
3.Zygote
4.Oviparous
5.Binary