Question

In the given image of Opuntia plant, identify the purpose of the flattened green structures marked as X.

• A. To reduce the rate of transpiration
• B. To perform photosynthesis
• C. to increase the rate of transpiration
• D. To provide physical support to the plant

Answer 1

The correct option is B To perform photosynthesis

Opuntia is a xerophytic plant which is adapted to live in the hot and arid climate of deserts. Opuntia shows various morphological adaptations.

Opuntia, have mechanisms to reduce the rate of transpiration (loss of water in the form of water vapour through stomata) to prevent excessive water loss. Their leaves are, modified into thin and sharp spines (leaves have more stomata normally) to reduce the exposed surface area to sunlight, thereby reducing the water loss through transpiration. Hence option a and c are incorrect.

To compensate for the loss of leaves which are involved in photosynthesis, the stems are modified into flat green leaf-like structures called phylloclades that contain chlorophyll and can perform photosynthesis (prepare food for the plant). Hence option b is correct.

Opuntia does not have any specialised structures for support. For example, tendrils in pea plants helps in climbing. Hence option d is incorrect.