1. Plant Hormones

2. Stimulus A change in organism’s environment

3. Stimulus

4. Response An organisms reaction to change.

5. Response

6. Tropisms Tropism = plant’s growth response toward or away from a stimulus through the action of auxins.

7. Phototropism Plants grow toward a source of light

9. Explain how a plant grows towards light. (4 marks) 2.The auxins diffuse down the shoot and cause cells behind the tip to elongate. 3.There is greater growth on the shady side of the young shoot. 4. The shoot grows towards the light - this is known as PHOTOTROPISM. 1.Auxins are produced in the shady side of the tip.

11. Gravitropism  A plant grows with or against gravity A plant’s stems or trunk grow up, against the pull of gravity. A plant’s roots grow down, with the pull of gravity

12. Can you explain the use of hormones in each diagram. Click to reveal the answer. Applications of plant hormones

13. Can you explain the use of hormones in each diagram. Click to reveal the answer. Fresh fruits are shipped around the world. Plant hormones are used to slow the ripening of the fruit, so they are just ripe as they reach the supermarket. Applications of plant hormones

14. Can you explain the use of hormones in each diagram. Click to reveal the answer. Applications of plant hormones

15. When a gardener takes cuttings from a plant, the base of each cutting is first dipped into a rooting compound to stimulate the growth of roots. Many rooting compounds contain auxin. Can you explain the use of hormones in each diagram. Click to reveal the answer. Applications of plant hormones

16. Can you explain the use of hormones in each diagram. Click to reveal the answer. Applications of plant hormones

17. Auxins can be sprayed onto flowers so that the fruits develop without pollination or fertilisation. These fruits are seedless. Can you explain the use of hormones in each diagram. Click to reveal the answer. Applications of plant hormones

18. Can you explain the use of hormones in each diagram. Click to reveal the answer. Applications of plant hormones

19. Weeds have broader leaves than the grass on a lawn. The weeds will take up more auxin than the grass when the lawn is sprayed. Can you explain the use of hormones in each diagram. Click to reveal the answer. Auxins can be used as herbicides. The weeds will grow too quickly and die.

20. Task Describe three uses of auxins. (3 marks)

21. True or false? Young roots always grow downwards. This is because roots are... 1. positively phototropic 2. negatively hydrotropic 3. positively geotropic Which of the following statements is true? Click to reveal the answer.

22. True or false? Young roots always grow downwards. This is because roots are... 1. positively phototropic 2. negatively hydrotropic 3. positively geotropic Which of the following statements is true? Click to reveal the answer.