Question

In $C_3$ plants first stable product of photosynthesis during dark reaction is
a. PGA
b. PGAL
c. RUBP.
d. Oxaloacetic acid.

Answer 1

Hint: $C_3$ plants are generally described as the plants that exhibit 3 carbon pathway, and in this plants Calvin cycle takes place in dark reaction of photosynthesis, and this plants do not have kranz anatomy, and 95% of all plants, shrubs, etc shows $C_3$ pathway.

Complete answer:
- In $C_3$ plants, most of the photosynthesis generally occurs only in the mesophyll cells, that too on the surface of the leaves.
- The plants have $C_3$ photosynthesis, they should have a cool and wet environment. Almost 95% of all plants exhibit the $C_3$ pathway.
- $C_3$ plants occur mostly in the temperate climate, and in these plants photorespiration does not suppress.
- In $C_3$ plants, photosynthesis occurs only when the stomata are open, and in these plants carbon fixation occurs very slowly.
- Optimum temperature required for the photosynthesis should be less in $C_3$ plants compared to $C_4$.
- The $C_3$ photosynthesis is very old and common, and in this plant carbon fixation occurs only once.
- The leaves of $C_3$ plants have only granal type of chloroplast.
- The chloroplast of $C_3$ plants have RUBISCO, and the first stable product formed in the dark reaction of Photosynthesis in these plants is 3 carbon compounds that are 3 phosphoglyceraldehyde.

Hence, the correct answer is option (A).

Note: Majority of the plant species on the earth takes $C_3$ photosynthesis, where 3 carbon compounds are formed first, where some plants which are in moderate water available areas, another type of carbon fixation called $C_4$ takes place.