Question

High CO₂ compensation point is found in
A. C3 plants
B. C4 plants
C. CAM plants
D. Lichen

Answer 1

Hint:-High CO2 compensation point is found in plants in which photorespiration occurs as this process increases the output of carbon dioxide. Carbon dioxide is a limiting factor to photosynthesis.

Complete step-by-step solution:-
All the plants use photosynthesis in order to convert light energy into chemical energy and carbon dioxide is a limiting factor to photosynthesis.
There is no net evolution of carbon dioxide gas at the compensation point because the rate of photosynthesis is equal to the rate of respiration which means the consumption of CO2 in photosynthesis is equal to evolution of CO2 in respiration.
Concentration of carbon dioxide affects differently on for both C3 and C4 plants-
Due to photorespiration in C3 plants, high CO2 compensation point is found as photorespiration increases the output of carbon dioxide and thus the compensation point is achieved at higher carbon dioxide concentration.
In C4 plants there is no photorespiration due to which compensation point is achieved at a lower atmospheric carbon dioxide concentration.
If we look at options now, option A is C3 plants. This option is correct as due to photorespiration in C3 plants, compensation point is achieved at a higher atmospheric carbon dioxide concentration. Therefore, this option is the correct one.
Moving to option B which is C4 plants. This option is incorrect as due to absence of photorespiration, compensation point is achieved at a lower atmospheric carbon dioxide concentration. Therefore, this option is incorrect and it gets eliminated.
Moving to option C which is CAM plants. These plants gather sunlight during the day and fix carbon dioxide during night only. This option is incorrect as the High CO2 compensation point is not found in CAM plants. Therefore, this option is incorrect and it gets eliminated.
Last option D is Lichens. Lichens are the organisms which arise from cyanobacteria. This option is incorrect as there is no carbon dioxide compensation point in lichens and they do not perform the process of photosynthesis. Therefore, this option is incorrect and it gets eliminated.
Thus, the correct answer is option A which is C3 plants.

Note:- C3 plants show high CO2 compensation point as in C3 plants, there is photorespiration which increases the output of carbon dioxide and thus the compensation point is achieved at higher carbon dioxide concentration. But it is absent in C4 plants due to which compensation point is achieved at a lower atmospheric carbon dioxide concentration.