The Law of Limiting Factors was proposed by:

What specialized photosynthetic pathway do some desert plants have?

The concentration of $CO_2$ in the atmosphere is $...............$ and if the concentration of $CO_2$ is increased up to $\ldots \ldots \ldots$,it can lead to an increase in the rate of $CO_2$ fixation.

The diagram below shows three plants with identical leaf surface areas. Assuming all other conditions were identical for all three plants,which of the plants would likely photosynthesize slowest,and which fastest?

The excess amount of $CO_2$:

Assertion : The atmospheric concentration of $CO_2$ at which photosynthesis just compensates for respiration is referred to as $CO_2$ compensation point.
Reason : The $CO_2$ compensation point is reached when the amount of $CO_2$ uptake is less than that generated through respiration because the level of $CO_2$ in the atmosphere is more than that required for achieving $CO_2$ compensation point.