The effect of gravity on the growth of seedlings: practical | Biology

Starter quiz

Which plant hormones control phototropism?

'Auxins' ✓
Match each part of the plant to the effect auxin has on it.

roots

⇔

auxin inhibits elongation of the cells ✓

shoots

⇔

auxin promotes elongation of the cells ✓
What is a tropism?

a response to gravity

a response to light

a response to water

a response to a stimulus ✓
Look at this image of a shoot. From which direction is the light coming?

left

right ✓

above

below
Gravitropism is a plant's response to ______.

'gravity' ✓
Where has auxin gathered in the root pictured?

at the top side of the root

at the bottom side of the root ✓

Exit quiz

Which of the following are features of biological drawings?

stippling ✓

shading

sketching

labels ✓

continuous lines ✓
What is the plant response to gravity known as?

'Gravitropism' ✓
True or false? Shoots use positive gravitropism.

True

False ✓
Put these steps in the right order for investigating gravitropism.

1

⇔

Soak the beans for 24 hours and then select three that have germinated.

2

⇔

Secure in a zipped food bag with wet kitchen roll.

3

⇔

Pin the bag up and water daily.

4

⇔

Rotate the bag after 3 days.

5

⇔

Observe the growth of the seedlings and produce scientific line drawings.
In roots, auxin ______ growth.

'inhibits' ✓
In the following example, why has the shoot grown upwards and the root grown downwards?

The auxin accumulated on the upper side of the shoot, promoting cell elongation.

The auxin accumulated on the upper side of the root, inhibiting cell elongation.

The auxin accumulated on the lower side of the root, inhibiting cell elongation. ✓

The auxin accumulated on the lower side of the shoot, promoting cell elongation. ✓

Worksheet

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Presentation

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Video

Lesson Details

Key learning points

Investigating the response of germinated seedlings to gravity (e.g. germinated beans placed vertically and horizontally)
Producing accurate, labelled scientific drawings to depict the growth response
Interpreting and describing the results
Explaining the growth response of seedlings to gravity using ideas about auxins and gravitropism

Common misconception

Pupils may think that a drawing must be as realistic as possible hence sketching is encouraged. Pupils may also think that roots will continue to grow in the direction that they start.

Emphasise that a line diagram is a simple representation of an object so sketching is not best practise. This lesson explains how roots will grow in the direction of gravity even if their orientation is changed.

Keywords

Auxin - plant hormones that affect the growth of plants
Gravitropism - a plant growth response towards or opposing the direction of gravity
Scientific line drawing - simple representation of a real object
Conclusion - summary of the results of an investigation with data and scientific explanations