Question

Observe the following diagrams:

1. What change will be observed in Cases ‘P’, ‘Q’ and ‘R’? Give reasons.
2. In which case:
   1. is aerobic respiration taking place?
   2. is fermentation taking place?

Answer 1

a. In case P, there is no change in lime water because no carbon dioxide (CO₂) is produced, so lime water remains clear.

In case Q, lime water turns milky because carbon dioxide (CO₂) from exhaled air reacts with lime water to form calcium carbonate.

In case R, lime water turns milky because yeast ferments sugar and releases CO₂, which makes lime water milky.

b. i. Aerobic respiration takes place in case Q.

ii. Fermentation takes place in case R.