Question

Photorespiration causes a plant to lose 25% of the carbon fixed, so C4 plants are much more efficient. Why aren't C4 plants more widespread? What kinds of environments would you expect to find them?

Answer 1

C4 plants are much more efficient as compared to the C3 plants because they tend to lose around 25% carbon that is fixed. Since the C4 plants don’t perform photorespiration, it is able to keep its stomata closed for a longer during hot conditions. The C4 plants are able to use the PEP carboxylase and hence it is able to fix C02. The C4 plants are less widespread as compared to the C3 plants because of the lack of photorespiration and hence it is not able to grow in all sorts of environment like the C4 plants. In the C4 plants, it fixes the atmospheric C02 in the mesophyll cells and forms oxaloacetate with help of a non-rubisco enzyme, PEP carboxylase and this enzyme is not able to bind 02. The oxaloacetate converts into malate which is transported to bundle sheath cells and it release the CO2. Hence since it is not able to undergo photorespiration, it is less widespread as compared to the C3 plants.

The C4 plants are mostly found in tropical and sub-tropical areas and within most of the dry conditions. This is because as they are not able to undergo photorespiration, they are able to keep their stomata closed for long time even when the heat is more and hence they mostly are able to grow in warm and humid climate. They mostly grow in dry and warm areas and are mostly found abundant in various tropical conditions.