B3.2.6 - Plant hormones

Question 1

What is positive phototropism?

Answer 1

Growing towards a light source

Question 2

What is positive gravitropism?

Answer 2

Growing in the direction of gravity

Question 3

What is negative phototropism?

Answer 3

Growing away from a light source

Question 4

What is negative gravitropism?

Answer 4

Growing away from the direction of gravity

Question 5

What is auxin?

Answer 5

A plant hormone that enables a plant to grow towards or away from a stimulus

Question 6

Where is auxin produced?

Answer 6

Made in cells near the tips of plant shoots or roots

Question 7

How do shoots grow towards light?

Answer 7

• Light causes auxin to build up on the dark side of the shoot tip
• Auxin now spreads down the shoot
• Cells on the darker side grow faster than cells on the lighter side
• This causes the shoot to grow towards the light

Question 8

How do the roots grow towards gravity?

Answer 8

• Auxin is produced in the root but gravity causes the auxin to concentrate on the lower side
• In the roots auxin inhibits cell growth so the lower side now grows more slowly than the upper side
• This causes the roots to grow towards the force of gravity