9.3 Chemical control in plants

Question 1

What hormone is used in plants to control growth

Answer 1

• Auxins

Question 2

Where are auxins produced

Answer 2

• tip of shoot, meristems

Question 3

Explain how auxins work as a photoreceptor

Answer 3

• Auxins produced in meristem of tip of shoot
• Diffuse down to area of elongation
• Binds to cell membrane of plant cell and activates H+ ion pump
• H+ ions move into membrane space and reduce pH, causing bonds between cellulose molecules to break and allows water to enter
• Cell becomes more turgid and expands.
• When cell matures, enzyme is denatured.