Question

Tabulate any four differences between C3 and C4 pathways.

Answer 1

The C3 and C4 pathways are two types of carbon dioxide fixation during the process of photosynthesis. The basis of difference is the different plants, processes required, stomatal opening due to the process, different intermediate molecules, and many more.

Complete answer:

C3 pathway	C4 pathway
This type of pathway occurs in all plants	It occurs only in C4 plants.
Phosphoglyceric acid – a three-carbon acid is the first stable intermediate product of the C3 pathway.	Four carbon acid – oxoacetate is the first stable product of the C4 pathway.
The process of photosynthesis occurs only in the mesophyll cells of the plants.	In C4 plants photosynthesis takes place in both mesophyll cells and bundle sheath cells.
C3 plants constitute 95% of green plants.	Only 5% of the green plants are C4 plants.
In C3 plants Kranz anatomy is absent.	Kranz anatomy can be seen in the leaves of C4 plants.
The fixation of carbon dioxide occurs only once.	In C4 plants fixation of carbon dioxide takes place twice.
Photorespiration is not suppressed in C3 plants.	In C4 plants the process of photorespiration is suppressed.
The fixation of carbon dioxide is slow in C3 plants.	The rate of carbon dioxide fixation is faster in C4 plants.
In C3 plants the process of photosynthesis occurs when stomata are open.	Even if the stomata are closed, the process of photosynthesis takes place in C4 plants.

Note: The C3 plants are also called temperate plants and are also referred to as light-independent reactions in the process of photosynthesis. This is because they use the ATP and NADPH formed in the light-dependent reaction for their further chemical reaction. The C3 pathway is also called the Calvin cycle and the C4 pathway is also called the Hatch – Slack pathway.