Class 8 Science Chapter 6 HOTS Questions - Reproduction in Animals

Q1: Although two cells called gamete fuse, the product formed is a single cell called zygote. Justify.
Ans: 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.

Q2: The eggs of frogs do not have shells for protection, yet they are safe in water. How?
Ans: 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.

Q3: Mother gives birth to a baby but the baby has characters of both parents. How?
Ans: 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.

Q4: Why do only male gametes have a tail?
Ans: Male gametes have to reach non-motile female gamete in oviduct from the vagina. So they have a tail to reach the egg cell.

Q5: Though hen and frog both are oviparous but they have different types of fertilisation. Justify.
Ans: 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.

Q6: How does twinning occurs during sexual reproduction?
Ans: 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.

Q7: 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?

Ans: 

• 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.