What is the characteristic of C3 Plants versus C4 Plants?

Question

What is the characteristic of C3 Plants versus C4 Plants?

Answer 1

C3 is the typical carbon fixation reaction that occurs in many plants using the Calvin cycle.  In C3 plants, CO2 is brought in, joins with ribulose-biphosphate and immediately enters the Calvin Cycle to produce glucose.

However, C4 plants, which typically live in hot, sunnier environments, spatially separate the initial carbon fixation stage from the Calvin Cycle.  They bring in CO2 and make malic acid in the mesophyll cells and then shuttle that to deeper bundle sheath cells where the CO2 is stripped off and sent to the Calvin Cycle.

Although C4 plants require more energy, their separation of the two phases allows them to fix a lot of carbon when it is cooler and the threat of water evaporation isn't great, and then still carry on the Calvin Cycle even if they have their stomata closed to prevent water loss later.