(a) Define geotropism. Give one example of geotropism.(b) What is meant by 'positive geotropism' and 'negative geotropism? Give one example of each type. Draw a labelled diagram to illustrate your answer indicating the plant part which shows positive geotropism and the plant part which shows negative geotropism.(c) Name one plant part which exhibits positive thigmotropism.

(a) Geotropism is the movement or growth of plant parts in response to the force of gravity. Just like phototropism, geotropism is also caused by an unequal distribution of auxin hormones.

An example of geotropism is the growth of roots towards gravity (downwards). 

(b) If the movement or growth of the plant parts is towards the pull of gravity (downwards), it is known as positive geotropism, whereas if the movement of the plant parts is against or opposite to the pull of gravity (upwards), it is known as negative geotropism.

Example- Positive Geotropism - Roots (grow downwards), Negative Geotropism - Stem (grow upwards).

(c) Tendrils or climbing organs of a plant exhibit positive thigmotropism.

Thigmotropism is the turning or bending of a plant part in response to a touch stimulus.

Tutorialspoint

Updated on: 24-Mar-2023

79 Views

Kickstart Your Career

Get certified by completing the course

Get Started