Nutrition in Plants — Science STD 7 — Question

Observation : The solution obtained after the addition of water to the glass jar turns blue litmus paper to red.

Explain chemical reaction along with examples.

Why is it important to use correct symbols in circuit diagrams?

What is the relation between the rate of heartbeat and pulse rate? If a pulse rate of an athlete Is 96/ min, what will be the number of his heartbeat at the same time?

Sahil says that stomach acid is harmful. Do you agree or disagree? Justify.

A food stall owner was preparing dough for making bhaturas. He added a pinch of yeast and sugar to the dough and left it in a warm place. After few hours, the dough had risen. There was a sour smell too. What would have happened if the dough was kept in the refrigerator, soon after it was prepared?

How does the heat from the sun reach us?

While learning to ride a bicycle, Boojho lost his balance and fell. He got bruises on his knees and it started bleeding. However, the bleeding stopped after some time.
(i) Why did the bleeding stop?
(ii) What would be the colour of the wounded area and why?
(iii) Which type of blood cells are responsible for clotting of blood?

Name the three digestive glands in our body.