One day, Ganesh asked his father why is government so much worried about decreasing population of tigers ? His father replied that it is important to save the tiger as they are at the end of food chains in forest ecosystem and play a role to keep the biotic components in ecosystem in balance.
Read the above passage and answer the following questions:
(i) What is a food chain ?
(ii) What is an ecosystem ?
(iii) What value is displayed by Ganesh's father?

In every summer, Ravi used to visit his native village. Many years ago when he was a small child, a large amount of soil was removed from his village land for construction purpose and as a result a pond was formed after rainy season. Every year, he observed gradual changes in the vegetation of the pond.
Read the above passage and answer the following questions:
(i) What is the term used to describe the process of colonization of a new barren area?
(ii) Define climax. What is the status of climax community?

Grandfather told his grandson Arun that many years ago in Uttrakhand, villagers started a movement to save trees of Himalayas by hugging the trees whenever contractors came to cut trees. This movement was effective in saving our forest wealth.
Read the above passage and answer the following questions:
(i) What is the name given to this movement?
(ii) How are trees imported for maintaining ecosystem?
(iii) What value was displayed by villagers?

Avinash went to his village during his summer vacations. One day, he decided to visit the nearby forest and asked his grandfather to accompany him. His grandfather told him about the recent cutting of forest and the new factory which had been established. Hearing this Avinash became curious and explained his grandfather about the ecosystem services.
(i) What are the benefits of healthy forest ecosystem?
(ii) Explain the contribution of Robert Constanza in ecosystem services.
(iii) What factors account for cost of various ecosystem services?
(iv) What values are shown by Avinash?

Pragyan takes fruits, vegetables, bread and egg curry in a day's menu.While his teacher was giving a lecture on trophic level, he got fascinated and asked following questions from his teacher.
(i) How many trophic levels does he occupy in different food chains?
(ii) Represent atleast three food chains.
(iii) Which among them gives him the maximum amount of energy? Give reason.
(iv) What values are shown by Pragyan?