Heat Transfer in Nature — Science STD 7 — Question

What health problems do workers in the silk industry suffer from?

What happens to the air we breathe in?

How does heat affect the changes happening around us?

Draw a diagram of stomata showing guard cells in it.

Does transpiration serve any useful function in the plants? Explain.

You must be familiar with the following nursery rhymes:

1. ‘Baa baa black sheep, have you any wool.’
2. ‘Mary had a little lamb, whose fleece was white as snow.’

Answer the following:

1. Which parts of the black sheep have wool?
2. What is meant by the white fleece of the lamb?

Why are open drains a concern?

Why should oils and fats not be released in the drain? Explain.

An adolescent often reacts strongly to minor disagreements, sometimes withdrawing and at other times lashing out. His/her relationships with friends and family are becoming strained. What might be contributing to such behaviour, and how can adolescents develop healthy responses to emotional changes?

A sewage treatment plant involves a few steps. Aeration tank, grit and sand removal tank, second sedimentation tank, bar screen, first sedimentation tank.
(i)Arrange all the above steps in the correct order in which they occur in the sewage treatment plant.
(ii)Which step gives most of the sludge?