Question

(a) Give the main points of difference between respiration in plants and respiration in animals.
(b) Describe the exchange of gases which takes place in the leaves of a plant (a) during daytime, and (b) at night.
(c) Which contains more carbon dixoide : exhaled air or inhaled air? Why?

Answer 1

(a)

Respiration in plants	Respiration in animals
All the parts of a plant perform respiration individually.	An animal performs respiration as a single unit.
There is little transport of respiratory gases from one part of the plant to the other.	Respiratory gases are usually transported over long distances inside an animal.
The respiration in plants occurs at a slow rate.	The respiration in animals occurs at a much faster rate.

(b) (a) During daytime, the leaves use some of the oxygen produced through photosynthesis for respiration. For photosynthesis, the leaves not only use the carbon dioxide produced through respiration, but some carbon dioxide is also taken in from the air.
Thus, during daytime, oxygen diffuses out and carbon dioxide diffuses in.

(b) At night, as photosynthesis does not takes place, oxygen is not produced. Thus, oxygen from air diffuses into the leaves to carry out respiration. And carbon dioxide produced by respiration diffuses out into the air. So, at night, oxygen diffuses in and carbon dioxide diffuses out.

(c) Exhaled air contains more carbon dioxide because we exhale to remove the waste product, i.e. carbon dioxide, from our body.