Question

(a) Quote three instances where human intervention saved the forests from destruction.
(b) Explain that it is a matter of chance whether a couple will give birth to a boy or a girl. Draw the necessary diagram to illustrate your answer.

Answer 1

(a) Three instances where human intervention saved the forests from destruction are -

• Chipko Andolan (Hug the Trees Movement):

This movement originated in a remote village called Reni, in Garhwal, in the early 1970s. A contractor was given permission to cut down the trees in a forest near the village. However, the villagers were against the decision. They were aware that diminishing forest cover would disturb the ecological balance. Therefore, there was a dispute between the contractor and the villagers. On a particular day, when the men folk of the village were away at work, the employees of the contractor visited the forest to cut down the trees. The women of the village then reached the forest, and each one wrapped her hands around a tree trunk, thereby preventing the workers from destroying the forest.

• Arabari forest range of Midnapore district, West Bengal:

Another example of active participation of people towards the conservation of biodiversity is found in an incident related to the Arabari forest range in Midnapore district, West Bengal. A forest officer, A. K. Banerjee, involved the villagers for the protection of the 1272 hectares of badly degraded Sal forests. In return, the villagers were provided with employment opportunities in silviculture and harvesting. They were also allowed to collect firewood from the forest. The effect of this involvement was that the forest became dense and green within a period of 10 years.

• Another example is the association of Bhishnois of Rajasthan

In 1971, Bishnois in Rajasthan gave up their lives while trying to prevent the king’s men from cutting trees.

(b) In human beings, the females have two X chromosomes and the males have one X and one Y chromosome. Therefore, the females are XX and the males are XY.

At the time of mating, large number of sperms is ejaculated from the male reproductive organ (penis), into the female reproductive organ i.e. vagina. They travel towards the fallopian tubes, where only one sperm meets with the egg.

The process of fusion of sperm and ovum is called fertilization. The sperm has either X or Y chromosome and egg has only X chromosome. So, if a sperm carrying Y chromosome fuses with the egg, the newly born child will be male and if a sperm carrying X chromosome fuses with the egg the newly born child will be female.

There is equal chance of fusion of either X or Y chromosome with the egg so we can say that the sex of new born child is a matter of chance and none of the parent is responsible for it.

Sex determination in human is shown below: