Question

Carbon particles and smoke from factories:
(A) Increase the rate of respiration in plants
(B) Decrease the rate of photosynthesis in plants
(C) Increase the absorption of carbon dioxide by plants
(D) Decrease the rate of transpiration in plants

Answer 1

Carbon particles and smoke get assimilated on the surface of the leaves of plants. This partially allows the light to impart on the leaves. Transpiration is the process by which water gets transferred to the environment by processes like evaporation.

Complete Step-by-Step Solution:
We will get some information about the pollutants like carbon particles and smoke.
- Carbon particles are made up of only carbon atoms and they are also called particulate matter. They are found to exist in different sizes.
- Smoke can be airborne particles or gases which are formed in combustion or pyrolysis reactions.
- The particulates of carbon and smoke can assimilate on the surface of leaves of the plants. These particles act as a barrier and do not let all the light to impart on some of the cells. As less light reaches the chlorophyll of the cell, the photosynthesis process occurs in a lesser amount. So, we can say that due to these, the rate of photosynthesis decreases in plants.
- Respiration occurs in plants by photosynthesis process. As the rate of photosynthesis decreases due to these pollutants, the rate of respiration also decreases.
- Due to their assimilation on the surfaces of leaves, the absorption of carbon dioxide also decreases.
- However, they do not have any effect on the transpiration process in plants.

- Thus, we can conclude that the correct option is (B).

Note: The carbon particles and smoke have direct and indirect toxic effects to the environment. Indirectly, they can change the pH of the soil after their solubilization. They block the stomata of the plants and the leaf gets covered partially.