Question

a.) What might be the role of root system in a plant? b.) Why does the modification of root occur? Write three reasons. c.) What are three reasons for the modification in stem of a plant?

Answer 1

The root is an underground part of the plant that absorbs water and minerals from the soil and anchors the plant firmly.

In some plants, the roots change their shape and get modified to absorb and transport water and minerals from the soil to different parts of the plant. They are also modified for support, food storage, and respiration.

The root modifications to perform two major functions- Physiological and Mechanical.

Explore more: Root System

Let us have a detailed look at the modification of roots.

Modifications of Tap Roots

For Food Storage

In some plants, the roots become fleshy due to the absorption of food material. The aerial parts of these plants worn out due to unfavourable conditions. When the conditions are favourable again new buds emerge either from the fleshy root or from a small bit of stem above.

For eg., the taproots of carrot and turnip get swollen to store food.

Depending upon their shapes, they are classified as;

Conical roots are broad at the base and conical at the apex, eg., carrot

Fusiform roots are swollen in the middle and tapering towards both the ends, eg., radish

Napiform roots are spherical at the base and taper towards the apex, eg., turnip

Tuberous roots have no specific shape. They appear thick and fleshy, eg., 4’O clock plant.

Also Read: Root Pressure

For better Respiration

In some halophytes such as Rhizophora that grow in swampy areas, the roots emerge out of the ground and grow upwards to get oxygen for respiration. The root tips of these plants have minute pores called lenticels through which they respire.

Nodulated Roots

Roots of the leguminous plants are modified into root nodules which contain nitrogen-fixing bacteria such as Rhizobium. They help in fixing the atmospheric nitrogen into nitrates and make it available to the plant.

Also Read: Modifications of Stem

Modification of Adventitious Roots

For Food Storage

Adventitious roots are modified into:

Simple Tuberous Roots are swollen and do not assume any shape. For eg., sweet potato

Nodulose Roots are single beads. They become swollen at the apex and have a definite shape, eg., ginger

Fasciculated Tuberous Roots is the cluster of adventitious roots for food storage. They have a definite shape, eg., Dahlia

Moniliform Roots are swollen and constricted, eg., grasses

Annulated Roots has an appearance of discs placed one over the other, eg., Ipecac.

For Support

Explanation:

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Answer 2

root helps the plants to stand in soil and transfer water through the stems Modification in root occurs when there occurs a permanent change in the structure of the root system. Roots are modified into different forms to perform specific functions other than their normal functions. Modification in roots is found in both tap root system and adventitious root system.Mar 20, 2019