Winds, Storms and Cyclones — Science STD 7 — Question

Explain why there is no waste in a forest.

How would you test the presence of starch in leaves?

State the characteristics of the image formed by a plane mirror.

Describe the role of water in life of animals and plants.

Describe the process of neutralisation with the help of an example.

Can we survive only on raw, leafy vegetables/ grass? Discuss.

Explain the following.
(i) Copper and aluminium wires are usually employed for electricity transmission. Explain the reason.
(ii) Explain how does the resistance of a wire vary with its length?
(iii) The tungsten is used almost exclusively for filament of electric lamp. Comment.

During a field trip, some students visited an agricultural farm and saw a few birds eating earthworms. They enjoyed the scene and then they also started picking and killing the earthworms for pleasure. Seeing the crowd of students in a corner, the teacher rushed to them to see the matter and objected to their action. Anshul, one of the student asked the reason. Teacher smiled and explained him that an earthworm living in the soil is very beneficial for farmers. Anshul wondered whether there were other organisms also in the soil. The teacher appreciated him and explained.

1. Mention the importance of earthworm.
2. List some organisms living in soil.
3. What are the values shown by Anshul?