Plant Hormones
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Key stage 4
10.14 Plant Hormones
Answer the questions below using the first web site on the list-Hormones and plant
growth.
1.
2.
3.
4.
5.
6.
7.
8.
What are plant hormones?
What stimuli are plants sensitive to?
What is the response of shoots to light called?
What is the name of the plant hormone that affects the responses of plants to
stimuli?
Look at the photograph of cress that has had light shining on it from one side.
Describe its appearance.
Look at the diagram beside the photo and then describe how the change is
brought about.
What is the advantage to the plant leaves that they show positive
phototropism?
Read the final section of this page and then describe how humans can use their
knowledge of plant hormones to their advantage.
Now go to the s-cool web site - it is the second one on the list.
Scroll down to the section on tropisms.
9. What is a tropism?
Work through the tasks on the screen.
Read about plant hormones and watch the movie that shows phototropism.
10. Describe what happens in roots when they are placed on their side.
11. What is the name of this type of tropism?
12. Read through the uses of hormones – if there are any there that you didn’t use
in your answer to question 8 then write them down now.
Now use the Bitesize site (the third link on the list) and work through the five
sections. When you have read the revision section – take the test.
Finally work through the last website on the list – plant hormones animation.
13. Copy the final diagram (test yourself) with the labels in the correct position.
By the end of this lesson you should have found out that:
Plants are sensitive to light, moisture and gravity:
their shoots grow towards light and against the force of gravity;
their roots grow towards moisture and in the direction of the force of gravity.
Plants produce hormones to coordinate and control growth.
The responses of plant roots and shoots to light, gravity and moisture are the result
of unequal distribution of hormones, causing unequal growth rates.
The hormones which control the processes of growth and reproduction in plants can
be used by humans to:
• produce large numbers of plants quickly by stimulating the growth of roots from
cuttings;
• regulate the ripening of fruits on the plant and during transport to consumers;
• kill weeds by disrupting their normal growth patterns.