Plants need light and water for photosynthesis. They have developed responses called tropisms to help make sure they thrive towards resources of light and water.

You are watching: Which statement about plant tropisms is true?

Hopeful tropism is as soon as a plant grows towards the stimulus.

Phototropism is a growth response wright here the stimulus is light, whereas gravitropism (also referred to as geotropism) is a expansion response wbelow the stimulus is gravity.

Responses to stimuli of different parts of the plant

Stem response to light is positive phototropism (grows towards the light).

Root response to gravity is positive geotropism (grows in the direction of the force of gravity).


Auxin is a household of plant hormones. They are largely made in the tips of the thriving stems and roots, which are the meristems. They can diffusage to other nlinux.orgmponents of the stems or roots. Auxin adjust the rate of elongation in plant cells, managing their size.

Stems and roots respond in different ways to high nlinux.orgncentrations of auxin:

cells in stems prosper morecells in roots grow less


In a stem, the shaded side has even more auxin and grows longer – leading to the stem to bfinish towards the light.

QuestionCan you define why these three shoots have actually grown in the method they have?

Gravitropism is a development response in a plant to the force of gravity. If a young plant was put on its side – as presented in the diagram – these are the expansion responses which would certainly occur.

In a root placed horizontally, the bottom side includes even more auxin and also grows less, causing the root to bend in the direction of the pressure of gravity.

In a stem put horizontally, the bottom side nlinux.orgnsists of more auxin and grows more, causing the stem to bend upwards versus the pressure of gravity.

See more: Why Is It Important To Elevate The Anthers In A Flower? Why Is It Important To Elevate The Anthers

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Homeostasis – WJEC

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