Question

Name any two ${{C}_{4}}$ plants. Describe how carbon dioxide is fixed in such plants.

Answer 1

${{C}_{4}}$ plants are defined as a plant that uses the hatch and slack pathway also known as ${{C}_{4}}$ pathway during the dark reaction. It mainly functions in bundle sheath or mesophyll cells. Carbon dioxide is fixed twice in reaction during the pathway. It is believed that more or less 5% of plants are ${{C}_{4}}$ plants.

Complete answer:
Let’s discuss the question and find the correct answer.
As the four-carbon compounds i.e oxaloacetate are formed during the hatch and slack pathway, the pathway is called ${{C}_{4}}$ pathway and the plants are ${{C}_{4}}$ plants. Examples of ${{C}_{4}}$ plants are sugarcane, maize, sorghum, etc.
During the pathway, these plants are not involved in the direct fixation of carbon dioxide. Here it differs with ${{C}_{3}}$ plants that use carbon dioxide directly for the fixation during the Calvin cycle. Carboxylation takes place in the first step where PEP i.e. phosphoenolpyruvate is formed from pyruvate or pyruvic acid in presence of the enzyme PEP carboxylase. PEP can bind with carbon dioxide and then reacts with each other. Hence resulted into the formation of a four-carbon oxaloacetate compound. The process of photorespiration is by-passed and the loss of carbon dioxide can be minimized during this process.

Note: plants are able to survive in dry or tropical environments. Their leaves are of special types. The leaves can often show a special type of anatomy which is known as kranz anatomy. During the pathway, photosynthesis can also occur in the absence of stomata.