HORMONES1)Where do they come from?

2)How do they travel?

3)Where are they broken down?

4)What does adrenaline do?

5)What are the differences between nervous and hormonal control?

TropismObjective: To know how plants

respond to different stimuli

Key words:

Tropism: responding to a stimulus by growing towards it or away from it.

Phototropism: A tropism caused by light

Auxins: Plant hormones

Plants respond to stimuli in the environment just as humans do.This helps them to survive.

The shoots and leaves of a plant will follow the sun during the day, this is called phototropism.

This allows them to make plenty of food.

Auxins are hormones that control how plants respond to sunlight.

They make the cells on one side of the plant grow longer so that the shoot bends towards the light

1) What are auxins?2) Where is it made?3) What does it do?4) How is it broken down?5) How does light affect where auxins are on the

plant?6) What is the effect of this auxin distribution in

response to light?7) Define “phototropism”8) What other stimuls do plants respond to?9) How can plant hormones be used by plant

growers and scientists?10)Can you think of an experiment to investigate

auxins and phototropism?

PAGE 154, 155 “auxin and tropism”

MUST HAVE PLANT HORMONE INFO:

• Phototropism is growth in response to light, towards light.

• Geotropism is growth towards or away from to gravity.

• Tropism is controlled by auxins.• Auxins regulate differential growth (enhanced

growth in certain parts of the plant)

USE TO HUMANS

• We can sythesise a hormone which inhibits plant auxin.

• Can you think how this would be useful?

• Synthetic hormones can block auxins. This stops a plant growing. This is used as an effective weed killer.