Question

The movement of the roots of a plant towards moisture in the soil is known as
A. Hydrotropism
B. Hygrotropism
C. Geotropism
D. Thigmotropism

Answer 1

Tropisms: When the direction of external stimulus decides the direction of response within the sort of growth it's called tropism. Thus, tropism is that the directional growth movement of a natural object. It is often within the direction of the stimulus or faraway from the stimulus.

Complete answer:
Tropism is a biological phenomenon, indicating growth or turning movement of a biological organism, usually a plant, in response to an environmental stimulus.
-If the expansion of a plant is within the direction of stimulus, it's called positive tropism.
- If the expansion of a plant is within the other way or faraway from that of a stimulus, it's called negative stimulus.
Types of tropism: There are five stimuli within the environment. They're defined below:
Phototropism:
When a natural object moves in response to light, it's called phototropism. If the stem of a growing plant moves or bends towards light, it's positive phototropism and if the foundation of a plant moves aloof from light, this suggests the roots of a plant shows negative phototropism.
The stem and leaves of a plant moves within the direction of sunlight. So, when a plant is grown in an open ground where sunlight is coming from above then the stem of a plant grows straight in an upward direction. If, however, a plant is kept in an area where sunlight is coming from only 1 direction then the stem of a plant bends in this direction only. On the opposite hand roots of a plant bend faraway from the direction of sunlight.
Geotropism:
When a natural object moves in response to gravity, it's called geotropism. As an example, roots of a plant move in a very downward direction, so that they show positive geotropism and stem moves within the upward direction, so it shows negative geotropism.
Roots of the plant grow towards the planet which shows positive geotropism and stem grows upward far from the pull of gravity which shows negative geotropism.
Chemotropism:
When a natural object moves in response to chemical stimulus, it's called chemotropism. The stimulus is chemical here.
Sugary substance acts as a stimulus for the expansion of plant parts towards the ovule. This happens because ripe stigma within the carpel of a flower secretes a chemical substance into the fashion towards the ovary. This sugary substance acts as a stimulus for the pollen grain which responds by growing a plant part within the downward direction into the fashion of a carpel and reaches the ovule of the flower for fertilisation.
Hydrotropism:
When a plant structure moves in response to water, it's called hydrotropism. Here the stimulus is water. Roots of a plant move towards water, so that they show positive hydrotropism.
Roots always grow within the direction of water, whether or not they need to grow against the pull of gravity or sideways.
Thigmotropism:
When a natural object shows directional movement in response to the touch of an object, it's called thigmotropism. As an example, tendrils of a plant climb towards any support which they touch.
There are some plants which cannot stand upright on their own and wish support. These plants are called climbing plants and have organs called tendrils. Tendrils are the skinny thread-like growth on the stems and leaves of the climbing plants. Tendrils are sensitive to the touch of other objects. When tendrils are available in contact with other objects, it bends towards the thing by growing towards it, wind round the object and take hold of it. This winding movement of a climbing plant is termed thigmotropism.

So, the correct answer is “Option A”.

Note: The Usefulness of Tropic Movements: Tropic movements help the plant to survive. For instance, roots of the plant are positively geotropic which is the reason that they'll always be downward into the planet whether or not they're planted the wrong way up. Also the basis will grow towards water because it is positively hydrotropic. Also the shoot will grow upward because it is negatively geotropic.