Assertion : The atmospheric concentration of $\mathrm{CO}_2$ at which photosynthesis just compensates for…
Assertion : The atmospheric concentration of $\mathrm{CO}_2$ at which photosynthesis just compensates for respiration is referred to as $\mathrm{CO}_2$ compensation point
Reason: The $\mathrm{CO}_2$ compensation point is reached when the amount of $\mathrm{CO}_2$ uptake is less than that generated through respiration because the level of $\mathrm{CO}_2$ in the atmosphere is more than that required for achi eving $\mathrm{CO}_2$ compensation point.
If both assertion and reason are true and reason is the correct explanation of assertion
If both assertion and reason are true but reason is not the correct explanation of assertion
If assertion is true but reason is false
If both assertion and reason are false.
Solution
At very low $\mathrm{CO}_2$ concentration photosynthesis is strongly limited by the 1 ow $\mathrm{CO}_2$ while respiratory rates are unaffected. As a result there is a negative balance between $\mathrm{CO}_2$ fixed by photosynthesis and $\mathrm{CO}_2$ produced by respiration and a net efflux of $\mathrm{CO}_2$ from the plant. By increasing the atmospheric concentration of $\mathrm{CO}_2$ at which photosynthesis just compensate for respiration is referred to as $\mathrm{CO}_2$ compensation point.