Photosynthesis In Higher Plants Question 106
Assertion : The concentration of $ O_2 $ in the atmosphere is inhibitory to photosynthesis. Reason : Oxygen inhibitory effect is due to the photoinhibition effect.
Options:
A) If both the assertion and the reason are true and the reason is a correct explanation of the assertion
B) If both the assertion and reason are true but the reason is not a correct explanation of the assertion
C) If the assertion is true but the reason is false
D) If both the assertion and reason are false
Show Answer
Answer:
Correct Answer: A
Solution:
Small quantity of oxygen is essential for photosynthesis except in some anaerobic bacteria.
The inhibition of photosynthesis at high $ O_2 $ levels may be due to (i) Oxygen takes part in oxidation of photosynthetic pigments, intermediates and enzymes in the presence of strong light (photo-oxidation), (ii) Oxygen is a strong quencher of excited state of chlorophyll, (iii) It converts RuBP carboxylase to RuBP-oxygen.
At a very high oxygen content the rate of photosynthesis begins to decline in all plants.
The phenomenon is called Warburg effect (increase due to photorespiration).
BETA
