Question

Assertion: Presence of pneumatophores (the respiratory roots) is a special adaptation of hydrophytes.
Reason: Pneumatophores help to take up oxygen from the atmosphere and transport it into the main roots.

A. Both assertion and reason are correct and reason is the correct explanation for assertion
B. Both assertion and reason are correct but reason is not the correct explanation for assertion.
C. Assertion is correct but reason is incorrect
D. Assertion is incorrect but reason is correct

Answer 1

Pneumatophores are the modified aerial roots that are commonly found in the mangrove areas having saline, swamp and muddy soil. In this type of soil, the plants do not grow easily because of the less availability of oxygen in the roots.

Complete Answer:
- Generally all the roots of the plants grows in the downward direction due to the positive gravitational force but in mangrove areas, the soil is saline, swamp and muddy in nature due to which the lateral roots grow upward out of the water and mud ( that is negative geotropic) to function as a site of oxygen intake for the submerged primary root system.
- Pneumatophores are found in halophytes i.e. plants grown in saline and muddy soil like soil of mangrove areas or sometimes in submerged hydrophytes.
- It is commonly seen in Rhizophora in which due to the saline soil, it is unable for the roots to perform the process of respiration. Hence the lateral roots move in an upward direction to provide oxygen to the primary roots of the plants. Due to this function it is also called respiratory roots or breathing roots.

The correct option is D i.e. Assertion is incorrect but reason is correct.

Note: The surface of these roots are covered with the small pore like structure called as lenticels which take up air into spongy tissue which in turn uses osmotic pathways to spread oxygen throughout the plant and thus help in the growth of the plant by providing proper oxygen and also remove excess of carbon dioxide from the plants.