Question

Thigmotropism is best exhibited by
A) Lamina
B) Tendrils
C) Root apex
D) Thorns

Answer 1

Hint:Thigmotropism is a process seen in plants. Here we will discuss all about thigmotropism – what is it, how does it occur, what are its consequences.

Complete answer:
Thigmotropism:
>Thigmotropism is also called haptotropism.Thigmotropism is the process in which a plant organ bidirectionally responds to touch or physical contact.
>The factor that can change the direction of plant’s growth is generally a hard surface.
>Thigmotropism can be in the form of coiling of plants around the surface, opening and closing of parts of the plants such as petals and sepals.
>This process is typically found in tendrils and twining plants but it can also be seen in flowering plants and fungi.
> The part of tendril that is in touch with the surface will produce a hormone called auxin and ethylene.
Types of Thigmotropism:
There are two types of thigmotropism:-
>Differential growth
>Rapid Contact coiling
Differential growth:-
In differential growth, one side of the plant grows faster than the rest of the plant upon stimulation.This growth can occur within minutes and is usually long lasting.
Rapid contact coiling:-
On the other hand, rapid contact coiling is an instant response.It does not last long lasting and happens quickly.Example – folding of leaves of some plant species when touched.
Hence, in the above discussion we have seen that the thigmotropism is best exhibited by tendrils.
So, option B is the right option.

Note: A tendril is a very thin thread like structure found in climbing parts and used for support. Tendril is a modified stem, petiole and leaf.