Phototropism What is phototropism and how does

it help plants survive?

Starter:

The circle on the board represents the Earth.

Come up and draw a plant growing somewhere on the Earth.

Learning Outcomes

Explain how phototropism increases a plant’s chances of survival

Describe how plant shoots grow towards a light source

H: explain phototropism in terms of the redistribution of auxin in shoot tips

Call my Bluff

• Phototropism –

Call my Bluff

• Phototropism – the movement of a plant in response to light.

• Phototropism – a professional picture of a plant.

• Phototropism – A 17 sided shape, mimicked in nature by some seeds.

Key words

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

Phototropism: the movement of a plant in response to light.

Auxins: Plant hormones

MRS GREN

What are the 7 signs of life?

SENSITIV

ITY

Think – Pair – Share

How are animals sensitive to the environment?

How do they respond to the environment?

Animal Sensitivity

Plants

Plants are sensitive to..

• Light• Gravity • Moisture

• What has happened to this plant? How is that an advantage?

Video time

• Phototropism

Direction of growth

The shoot grows:• Towards the light• Away from gravity

The root grows:• Away from light• Towards gravity• Towards moisture

phototropism

Phototropism animation

Auxins are hormones made by the shoot tip, 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.

Key word:Elongation

In small groups

On A3 paper draw what you think a stem would look like in the following situations.

1) With light to the right.2) With light to the left3) With light up above.4) With light to the right by no stem tip.

Task

• Complete the worksheet showing the directions plants move and the position of auxins.

Plenary

• Make a revision card with the key points about phototropism.

We are going to set up an experiment today to look at the way position of light affects the direction of growth of plants.

Method

1. Collect 3 petri dishes and line them with growing medium.

2. Water the growing medium.3. Place 6 seeds in each dish.4. Collect a coloured lamp and set it up on the

bench.5. Place the seeds 20cm away from the lamp

and place a box over the experiment.

Questions

1. What are we changing about the experiment?(What are we testing?)

2. What are we going to measure and take results of?

3. What do we want to keep the same so we don’t affect the results?

4. What do you think will happen in the experiment?