Sources of Energy — Science STD 10 — Question

A red-haired woman marries a brown-haired man, and all the children are brown haired. Explain this genetically.

What is meant by “electric power”? Write the formula for electric power in terms of potential difference and current.

Distinguish between tropic movements and nastic movements in plants. Give examples to illustrate your answer.

If you were going to connect two light bulbs to one battery, would you use a series or a parallel arrangement? Why? Which arrangement takes more current from the battery?

In an electrolytic tank, aluminium metal is being extracted by the electrolysis of molten aluminium oxide using carbon electrodes. It is observed that one of the carbon electrodes is gradually burnt away and has to be replaced.

1. Which carbon electrode (cathode or anode) is burnt away?
2. Why is this carbon electrode burnt away?

What is meant by trophic level in a food chain? Construct a terrestrial food chain with four trophic levels. The energy flow in a food chain is always unidirectional. Why?

Why is sustainable management of natural resources necessary? Out of the two methods–reuse and recycle–which one would you suggest to practise and why?

Despite nature's bounty, why is there a failure in sustaining the underground water sources?

An object is placed at a distance of 15 cm from a concave lens of focal length 30 cm. List four characteristics (nature, position, etc.) of the image formed by the lens.