medium importancemedium difficulty5 min

Geotropism

Geotropism is the growth movement of a plant part in response to gravity.

In one line: Geo means earth, so geotropism means gravity-guided growth.

Practice This Concept

Understand it

Geotropism is also called gravitropism.
Roots usually show positive geotropism because they grow downward in the direction of gravity.
Shoots usually show negative geotropism because they grow upward against gravity.
This helps the plant survive by placing roots in the soil and shoots towards light and air.

Example

A germinating bean root growing downward into the soil shows positive geotropism.

Rule to remember

Rule: geotropism is directional growth due to gravity; roots are usually positive and shoots are usually negative.

See it worked out

Follow the example line by line, then use the same method on new questions.

Worked example

1When a seed germinates, the root grows downward into the soil.
2This is positive geotropism because the root grows in the direction of gravity.

Method you can reuse

1Identify gravity as the stimulus.
2Observe whether the part grows down or up.
3Name root or shoot response.
4Decide positive or negative geotropism.
5Write the reason clearly.

Visual tip

A simple diagram should show a seedling with roots downward and shoot upward, with gravity marked by an arrow.

Check yourself

Answer the question in your head before opening the answer.

Try it yourself

Why do roots usually show positive geotropism?

Think first, then show answer

Roots usually show positive geotropism because they grow in the direction of gravity. This helps them enter the soil, hold the plant firmly, and absorb water and minerals.

Common wrong answer

A common wrong answer is to say shoots show positive geotropism because they grow upward.

Why it loses marks: Upward growth is against gravity, so it is negative geotropism.

Don't mix this up

Students often think downward growth always means the plant is weak or damaged. In fact, roots growing downward is a normal response to gravity.

Exam tip

If the stimulus is gravity, use geotropism and mention whether the part is moving toward or away from gravity.

Write it in the exam

Each point is worth about one mark. Write point 1 for a 1-mark question and keep adding points as the marks go up.

How CBSE asks it

Questions may ask the meaning of geotropism, the difference between positive and negative geotropism, or the response of roots and shoots to gravity.

1
Enough for 1 mark
Geotropism is the growth movement of a plant part in response to gravity.
2
Add for 2 marks
Example: A germinating bean root growing downward into the soil shows positive geotropism.
3
Add for 3 marks
Roots usually show positive geotropism because they grow downward in the direction of gravity.

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