Question

What is Kranz anatomy? Write a note on photosynthesis of those plants in which this anatomy is found.

Answer 1

Hint: The term kranz is also called wreath or ring, and it is the specialized structure in $C_4$ plants, where the group of mesophyll cells is form clusters, around the bundle sheath cells in the form of the ring like fashion.

Complete answer:
Kranz anatomy is mainly formed in three different steps
- The Initiation of procambium occurs.
- There is a specification of the bundle sheath and mesophyll cells.
- Chloroplast development and integration of the $C_4$ cycle

Photosynthesis in Kranz anatomy
- In these plants, light-dependent reactions occur in mesophyll cells, while dark reactions occur in bundle sheath cells.
- In the $C_4$ plants, first, the oxygen of the atmosphere is fixed and it is converted into 4 carbon compound called oxaloacetate, which occurs by the enzyme called PEP carboxylase
- Later this oxaloacetate is converted to Malate and it enters the bundle sheaths and in bundle sheaths, malate dissociation occurs, which releases the carbon dioxide.
- Rubisco fixes the carbon dioxide, which converts to sugar
- The mesophyll cells constantly pump the carbon dioxide to the bundle sheath cells, and so carbon dioxide concentration is always high around the rubisco, which reduces photorespiration.
- The majority of the plants convert the carbon dioxide into 3 carbon compounds by the enzyme Rubisco, if this enzyme catalyses the reaction with oxygen, it induces the process of respiration.

Note: In $C_4$ plants, in order to avoid photorespiration, the carbon dioxide is fixed in the plants, and this carbon dioxide is again released into the atmosphere for refixation again. In $C_4$ plants like grasses, bundle sheaths, in turn, surrounded by the veins.