Question

Leguminous plants have their roots modified into-
a. Fibrous roots
b. Stilt roots
c. Nodulated roots
d. Prop roots

Answer 1

Hint: These roots form a symbiotic relationship of bacteria which fix nitrogen. They are capable plants form a symbiotic relationship under nitrogen limiting conditions with a host-specific strain of bacteria known as rhizobia.

Complete answer:
> Option A is incorrect. A fibrous root system forms a thick root network, closer to the surface of the soil. Examples of fibrous root systems include grasses such as wheat, rice, and corn and carrot. Fibrous root systems are found in monocots; dicots have tap root systems.

> Option B is incorrect. Stilt roots are the aerial adventitious roots that grow obliquely downward from the main stem 's basal nodes, and are securely attached to the soil. Such supporting roots occur in plants that grow along banks of the river, ponds etc. Examples: Red Mangrove Maize.

> Option C is correct. Rhizobium is a bacterium located within leguminous plant root nodules. It causes the creation of specific structures inside which it fixes atmospheric nitrogen, called nodules. It does this with the aid of nitrogenase enzyme, which transforms nitrogen to ammonium, which is an essential factor needed to grow plants. The bacterium, in turn, is getting shelter from the soil. Hence it modulates the roots of leguminous plants.

> Option D is incorrect. The roots of props are also known as roots of pillars. These are adventitious roots which grow in the trees from the broad horizontal branches, hang downwards and finally reach the field. This makes them appear like pillars. It is present in plants such as Ficus benghalensis (Banyan tree), Rubber plant, Corn etc.

Hence, The correct answer is option (C).

Note: The roots inside the cells that have the irregular or round mass, or a lump called nodules, are known as nodulated roots. Root nodules are tiny nodules-like swelling on roots. They provide shelter for the bacteria which fix nitrogen. These bacteria convert nitrogen from the atmosphere into nitrogen organic compounds.