CBSE Class 8 Science Chapter 6 Reproduction In Animals Short Answer Questions
Question 1. Describe the two modes of reproduction.
Answer: Two modes of reproduction are
Asexual reproduction. It does not involve the fusion of gametes, it results from the multiplication of body cells from a single parent. Daughter cells are identical to the parent. No fertilisation takes place.
Sexual reproduction is characterised by the union of male and female gametes coming from two parents. offspring differ from the parents genetically. Fertilisation takes place
Question 2. It is not necessary to produce a large number of eggs and spores by the animals that reproduce by external fertilisation. Why?
Answer: It is necessary to produce a large number of eggs and sperm by he animals that reproduce by external fertilisation to enhance the chances of fertilisation. As the gametes are released in water, many of them may he carried away by the movement of water, wind, etc., or may be eaten by other aquatic animals, so a large number is released to compensate for the loss.
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Question 3. Mother gives birth to a baby, but the baby has characteristics of both parents. How is this possible?
Answer: Although a mother gives birth to a baby, the baby is formed from the fertilisation of male and female gametes involving two parents. The nuclei of both the parent gametes fuse to form a zygote, thus passing their characteristics to the offspring. This zygote develops inside the female body (uterus) and finally takes birth as a baby
Question 4. Although two cells called gametes fuse, the product formed is a single cell called a zygote. Justify.
Answer: During fertilisation, only the nucleus of the sperm enters the egg cell to form a single-celled structure, which is called a zygote.
Question 5. Can a woman with a blocked Fallopian tube give birth to a baby? How?
Answer: A woman with a blocked Fallopian tube cannot produce babies in the normal way because the eggs released by their ovary cannot meet the sperm and get fertilised in the oviducts. But such women can have babies by using the ‘in vitro fertilisation’ technique.
Question 6. The test-tube babies are called so as they grow inside a test tube. Give your opinion.
Answer: The babies born through the IVF technique are called test-tube babies because the fertilisation takes place in a glass test tube. This is, however, a misleading name as a very brief period is spent in a test tube. After which, the entire growth and development of the baby takes place inside the uterus of the woman as in normal pregnancy.
Question 7. Observe the figure given and answer the questions that follow
Question 8. What happens during the process, and what is formed?
Answer: During the process, the sperm nucleus fuses with the egg nucleus to nun a zygote.
Question 9. The term metamorphosis is not used while describing human development. Why?
Answer: The term ‘metamorphosis’ Is not used while describing human development because in human beings, body parts of an adult arc present from the time of birth llsclf, i.e., while beginning of life as a baby and until you arc an adult, the basic plan of body does not change, On the contrary, in metamorphosis, the parts of the adult arc different from those at the time of birth,.
Question 10. What does the figure represent?
Answer: The figure represents the process of binary fission in Amoeba. During fission, a single Amoeba divides (both nucleus and cytoplasm) to form two daughter cells that develop into two independent Amoeba.