P-2 Towards Green Energy — Science STD 10 — Question

Distinguish between Direct current and alternating current.

How do butterflies contribute to environmental balance?

There are five animals A, B, C, D and E. The animal A uses its modified forelimbs for flying. The animal B uses its forelimbs for running whereas the animal C uses its forelimbs for grasping. The animal D can live on land as well as in water and uses its forelimbs to prop up the front end of its body when at rest. The animal E which respires by using spiracles and tracheae uses wings for flying but its wings are analogous to the modified forelimbs of animal A.

1. What could the animals A, B, C, D and E be?
2. Why are the forelimbs of animals A, B, C, D called homologous organs?
3. What does the existence of homologous organs in animals A, B, C and D tell us about their ancestors?
4. Why are the modified forelimbs of animal A and the wings of animal E called analogous organs?
5. State whether animals A and E have a common ancestor or not.

'Save energy' is the need of the hour.

Some hunters are roaming in the plush green forest of Africa. They spot a deer and kill it. They decide to roast the deer there and then and eat it. When the hunters had just finished enjoying the feast of roasted deer, a lion attacks them. The lion kills one of the hunters and eats his flesh.

1. Write a food chain which provides food to lion in this case.
2. Which animal (other than deer) the lion could look for food if he did not get the hunter as prey?
3. Which other animal in the forest could have been in place of lion?
4. How does the above food chain differ form the food chain such as: plants → goat → man?

Explain the need and importance of space missions.

How is nuclear fission reaction carried out in nuclear power plants?

Describe some experiment to show that the magnetic field is associated with an electric current.