Question

The movement of stem and root in response to the force of gravity is known as –
A. Geotropism
B. Hydrotropism
C. Thigmotropism
D. Chemotropism

Answer 1

This is a coordinated process, in response to gravity pulling on it, of differential growth by a plant or fungus. Here, Gravity can be either "artificial gravity" or natural gravity. Generally, it is a characteristic shown by all higher and many lower plants as well as other organisms.

Complete answer:
1. Geotropism is defined as the process of growth of plants as well as other organisms like fungi against the pulling force of gravitation. That gravitational force is either natural or artificial.
2. First-time scientist Charles Darwin told about the phenomenon of geotropism. He scientifically
proved that the roots of the plant show positive geotropism as they show growth towards the center of the earth whereas the stem of plants shows negative geotropism as they show growth away from the center of the earth.
3. It can be demonstrated by a simple activity with a potted plant. When we laid it onto a slide, the
a growing part of the stem bends with a small degree and shows negative geotropism by upward growth, on the other hand, roots also bends towards the center of the earth to show positive geotropism.
4. Hydrotropism is also a plant growth response against the water content. The growth pattern of roots against the water availability is known as hydrotropism.
5. when a plant and any other organisms respond by turning or bending against the touch stimuli it is
known as Thigmotropism.
6. In chemotropism growth of organisms is conducted by chemical stimuli from the outside of the
organisms. It can be seen in bacteria plants and fungi.
Hence from the above discussion, we can conclude that the growth of stem and root against the
the gravitational force is known as GEOTROPISM.

So, the correct answer is “Option A Geotropism”.

Note:
Example of thigmotropism is touch me not plant
An example of chemotropism is the production of pollen tubes by pollen grains.