Geotropism

The idea

In geotropism, roots grow downwards and shoots grow upwards, away from the earth, in response to the pull of gravity.

A seed in the soil

A seed sits in the soil. Nobody tells it which way is down. Still, its root goes down and its stem comes up into the air.

What do you think tells the root and the shoot which way to grow?

• The pull of the earth, or gravity
• The colour of the soil
• The size of the seed

Down and up

Press Next step.

Gravity decides

Gravity is the trigger. The root grows in the direction of the pull, and the shoot grows away from it.

In geotropism, roots grow downwards and shoots grow upwards, away from the earth, in response to the pull of gravity.

Notes

In geotropism, roots grow downwards and shoots grow upwards, away from the earth, in response to the pull of gravity.

Check yourself

In which direction do roots grow in geotropism?

In which direction do shoots grow in geotropism?

Which trigger causes geotropism?

A seed is planted in the soil. Which describes its root and shoot?

• Upwards, away from the earth. Shoots grow upwards, away from the earth.
• Sideways, towards the light. Roots grow downwards in response to the pull of the earth. Bending towards or away from light is phototropism.
• Downwards — correct. Yes!
• Upwards, away from the earth — correct. Yes!
• Downwards, towards the earth. Roots grow downwards.
• Towards the nearest root. Shoots grow upwards, away from the earth.
• Light. Light causes phototropism.
• The pull of the earth, or gravity — correct. Yes!
• Touch. Touch makes a tendril circle around a support.
• The root grows up and the shoot grows down. This is reversed. Roots grow downwards and shoots grow upwards.
• Both grow down into the soil. Shoots grow upwards, away from the earth.
• The root grows down and the shoot grows up — correct. Yes!