Question

${C_4}$Pathway is advantageous over ${C_3}$ pathway in plants as it
A. Occurs in relatively low $C{O_2}$ concentration
B. Uses more amount of water
C. Occurs in relatively low ${O_2}$ concentration
D. is less efficient in energy utilization.

Answer 1

Hint: Photosynthesis: It is a process in which organisms like green plants and some other organisms like prokaryotic bacteria convert a light energy into chemical energy.
Carbon fixation: Carbon fixation is an integral part of photosynthesis, and something that must be taken into account when engineering photosynthesis into a new host.

Complete answer:
Photosynthesis: It is the process by which green plants and certain other organisms transform light energy into chemical energy.
Photosynthesis: It is a process in which organisms like green plants and some other organisms like prokaryotic bacteria convert a light energy into chemical energy.
${C_3}$ Plants:
1. Primary product is 3-phosphoglyceric acid.
2. It occurs in mesophyll cells.
3. Photorespiration rate is very high.
4. Carbon fixation occurs only once.
5. Carbon dioxide fixation is slow.
${C_4}$ Plants:
1. Primary product is four carbon compounds oxaloacetate.
2. It occurs in mesophyll and bundle sheath cells.
3. Photorespiration rate is absent.
4. Carbon fixation occurs twice.
5. Carbon dioxide fixation is faster.
${C_4}$ ​pathway occurs in relatively low $C{O_2}$ ​concentration as carbon dioxide is recycled and not wasted.
${C_4}$ ​pathway uses less water than ${C_3}$ ​pathway
${C_4}$ ​pathway occurs in the same oxygen concentration as ${C_3}$ ​pathway.
${C_4}$ pathway is more energy efficient than ${C_3}$ ​pathway as it does not consume extra energy by avoiding the wastage of carbon dioxide.

So, the correct option is option Occurs in relatively low ${O_2}$ concentration.

Note: There are also a few similarities between the ${C_3}$ and ${C_4}$ plants:
1. Both the plants fix energy from sunlight.
2. Both synthesize carbohydrates.
3. They are the type of dark reactions of photosynthesis.
4. The site of photosynthesis is chloroplast in both types of plants.