Question

Write the differences between ${C}_{3}$ and ${C}_{4}$ pathways.

Answer 1

${C}_{3}$ plants exhibit the ${C}_{3}$ pathway. These plants use the Calvin cycle in the dark reaction of photosynthesis. The leaves of ${C}_{3}$ plants do not show Kranz anatomy. Here the photosynthesis process takes place only if the stomata are open. On the other hand, ${C}_{4}$ plants use the ${C}_{4}$ pathway during the dark reaction. The leaves show Kranz anatomy, and the chloroplasts of these plants are dimorphic.

Complete step by step answer:
The differences between ${C}_{3}$ and ${C}_{4}$ pathway are:

${C}_{3}$ Pathway	${C}_{4}$ Pathway
Ribulose bisphosphate is the primary acceptor of ${CO}_{2}$.	Phosphoenolpyruvate is the primary acceptor of ${CO}_{2}$.​
Only one type of chloroplasts are involved.	Chloroplasts of two different types are present in bundle sheath cells and mesophyll cells.
Phosphoglyceric acid, a 3C compound, is the primary stable product.	Oxaloacetic acid, a 4C compound, is the primary stable product.
The optimum temperature required for photosynthesis is between 20 to 25 degrees celsius.	The optimum temperature required for photosynthesis is between 25 to 35 degrees celsius.
Photorespiration is not avoided in this pathway	Photorespiration is avoided in this pathway.
Example- Sunflowers, spinach, beans, rice, and cotton.	Example- Sugarcane, sorghum, and maize

Additional information: During the ${CO}_{2}$ fixation, when the photosynthetic plants produce 3-phosphoglyceric acid or 3- carbon acid because the primary product is named C3 pathway. But when the photosynthetic plant, prior going to the ${C}_{3}$ pathway, produces oxaloacetic acid (OAA) or 4 -carbon compound as their first stable product is called as ${C}_{4}$ or Hatch and Slack pathway. When plants consume the energy of the sunlight in the daytime and utilize this energy for fixing the carbon dioxide at night time is known as crassulacean acid metabolism or CAM.

Note: Both the plants fix energy from sunlight. Both synthesize carbohydrates. ${C}_{4}$ plants minimize photorespiration by dividing the initial ${CO}_{2}$ fixation and the Calvin cycle in space, carry out these steps in several cell types. About 5 percent of plants on earth are C4 plants. The majority of plants are${C}_{3}$ plants, which haven't any special features to combat photorespiration. Approximately 95 percent of the shrubs, trees, and plants are C3 plants.