Question

Kranz anatomy is found in case of
A. Flower
B. Root
C. Leaf
D. Stem

Answer 1

Carbon dioxide available in the atmosphere is the inorganic form and it has to be converted by the plants into organic compounds. This process of conversion of inorganic carbon dioxide into usable organic form is known as carbon fixation. The process takes place through a series of reactions such as the Calvin cycle and which in some cases may lead to oxidation resulting in the loss of energy. In some plants, the loss is avoided by specific changes in the process by certain modifications in the anatomy of different structures such as leaves.

Complete answer:
The process of photosynthesis has several factors such as the amount of carbon dioxide, water and other environmental factors. Carbon dioxide is converted into forms that can be used by the plants in the process of photosynthesis or is known to be fixed and is referred to as carbon fixation. In the Calvin cycle or light dependent reaction, the carbon and water is fixed to carbohydrates. Carbon combines with Ribulose- 1 and 5- bisphosphate (RuBP) to produce two molecules of three carbon acids known as 3- phosphoglyceric acid (PGA) which is catalyzed by RuBisCO. RuBisCO has a dual affinity for carbon dioxide and oxygen. In some plants, RuBisCO binds to available oxygen molecules as a result the normal process is deviated and causes loss of ATP and loss of carbon dioxide.
The loss of carbon that is caused due to oxygenation by enzyme RuBisCO and inhibits photosynthesis is called photorespiration. In some plants, the loss is replaced by a special mechanism known as the C4 pathway as the first carbon acid is a four carbon acid which is either malate or aspartate.
The plants in which the process takes place are known as C4 plants. In this pathway, the organic acid which is produced in the mesophyll cells and are then transported to the bundle sheath cells through the plasmodesmata. The special arrangement of the plants help to achieve the desired system due to the presence of specialized anatomy in the leaves which is known as the Kranz anatomy. In this type of anatomy, the vascular bundles are two types of rings in which the internal one is the bundle sheath cells and the outer ring consists of mesophyll cells. This arrangement of vascular bundles appears as a wreath and helps to concentrate carbon dioxide around the enzyme RuBisCO and thereby avoiding loss due to photosynthesis.
The Kranz anatomy is specially present in the leaves of the C4 plants and not in the roots, stem or flowers and helps to fix carbon without any loss of energy.

Therefore, the correct option is option C.

Note: Carbon dioxide is fixed by the plants through specific processes but in some cases the enzyme RuBisCO due to its affinity to both carbon and oxygen deviates from the process of carbon fixation. The loss is overcome by specialized arrangement of vascular bundles of leaves in some plants known as the Kranz anatomy and it helps the loss by concentrating the carbon dioxide around the enzyme RuBisCO. Kranz anatomy is found in the leaves of a number of angiosperms which utilize the C4 pathway such as maize, sugarcane, sorghum and grasses.