Question

Assertion :Under conditions of high light intensity and limited $C{O}_2$ supply, photorespiration has a useful role in protecting the plants from photo-oxidative damage. Reason: If enough $C{O}_2$ is not available to utilize light energy for carboxylation to proceed, the excess energy may not cause damage to plants.

• A. Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.
• B. Both Assertion and Reason are correct but Reason is not the correct explanation for Assertion.
• C. Assertion is correct but Reason is incorrect.
• D. Both Assertion and Reason are incorrect.

Answer 1

The correct option is A Both Assertion and Reason are correct and Reason is the correct explanation for Assertion.

Light intensity is usually defined as the energy hitting an area over some time period. So, in the case of a plant, a higher light intensity means more packets of light called photons are hitting the leaves. Within the leaves, the mesophyll cells have a large number of chloroplasts that are responsible for Carbon dioxide fixation. Under conditions of high intensity and limited CO${}_2$ supply, photorespiration has a major role in protecting the plants from photooxidative damage. This means that if adequate CO${}_2$ is not available to utilise light energy for carboxylation to proceed, the excess energy causes damage to plants. However, photorespiration i.e., oxygenation of RuBP utilizes part of the light energy and saves the plants from photooxidative damage.

Thus, the correct answer is option A.