NEET2010BotanyPhotosynthesis in Higher PlantsActual
Assertion : Due to pollution atmospheric concentration of CO ₂ is increasing which will be harmful for C ₄ plants whereas productivity is going to increase for C ₃ plants. Reason : C ₄ plants have greater efficiency for CO ₂ as CO ₂ is fixed by PEP oxygenase.
Options
- AIf both assertion and reason are true and reason is the correct explanation of assertion
- BIf both assertion and reason are true but reason is not the correct explanation of assertion
- CIf assertion is true but reason is false
- DIf both assertion and reason are false.
Correct answer
C. If assertion is true but reason is false
Step-by-step solution
CO ₂ concentration of the atmosphere is 0.036 % or 360 ppm (360 l . l⁻¹ ) . It is a limiting factor for C ₃ plants as the available CO ₂ concentration is lower than the optimum for photosynthesis. Increase in its concentration upto 0.05 % increases the rate of photosynthesis in most C ₃ plants. When CO ₂ concentration is reduced, there comes a point at which illuminated plant parts stop absorbing carbon dioxide from their environment. It is known as CO ₂ compensation point or threshold value. At this value CO ₂ fix