$A -$ Productivity of $C_3$ plants is higher than $C_4$ plants.
$R -$ Photorespiration occurs in $C_3$ plants.

What is true for photosynthesis $-$

Maximum photosynthesis occurs by ..........

Select the correct option:
$(1)$ $C_4$ plants have double the efficiency of carbon fixation compared to $C_3$ plants.
$(2)$ Sugar is transported from source to sink through the $\text{phloem}$ / $\text{xylem}$ tissue.

Which of the following products of Hill's reaction are used in Blackman's reaction?

Assertion $:-$ There is not a complete one-to-one overlap between the absorption spectrum of chlorophyll $a$ and the action spectrum of photosynthesis.
Reason $:$ Most of the photosynthesis takes place in the blue and red regions of the spectrum,but some photosynthesis does take place at the other wavelengths of the visible spectrum.