Question

Which of the following characteristics out of I, II and III are exhibited by $C_4$ plants?
I. Kranz anatomy.
II. The first stable product of photosynthesis is oxalo acetic acid.
III. Both PEP carboxylase and ribulose-bis phosphate carboxylase act as carboxylating enzyme.
Choose the correct option.

• A. I and II, but not III
• B. II and Ill, but not I
• C. I and lII, but not II
• D. All of these

Answer 1

The correct option is D All of these

Kranz anatomy is the structure found in the C${}_4$ plants. This is the arrangement of the mesophyll cells which have few and small chloroplasts. These cells are surrounded internally by the bundle sheath cells which have many large chloroplasts.

The CO${}_2$ is fixed by PEP carboxylase in the mesophyll cells and the first stable product of photosynthesis is the oxalo acetic acid. This is 4 carbon compound and hence, the name of the pathway is C${}_4$ pathway.

The PEP carboxylase is present in the mesophyll cells and the RuBisCo is present in the bundle sheath cells. Both of these enzymes acts as carboxylating enzyme which helps in CO${}_2$ fixation.

Thus, the correct answer is option D.