Diffusion and surface area to volume ratio | Biology | Quizalize & Oak National Academy

Starter quiz

The area of this object is ______ cm².

'20' ✓
True or false? Diffusion is a passive process.

True ✓

False
What is the volume of this cube?

343 cm³ ✓

343 cm²

294 cm³

294 cm²
How many mm are in 4 m?

40

400

4000 ✓

40 000
What is the correct description of diffusion?

Net movement from a low to high concentration down a concentration gradient.

Net movement from a high to low concentration down a concentration gradient. ✓

Net movement from a low to high concentration against a concentration gradient.

Net movement from a high to low concentration against a concentration gradient.
What will happen to the particles of carbon dioxide?

They will move inside the leaf. ✓

They will move out of the leaf.

They will stay where they are.

Exit quiz

The volume of this shape is ______ cm³.

'40' ✓
A 4 cm wide cube takes 60 minutes to fully discolour. If we cut the cube into 4 new cubes each 2 cm wide, how long would each cube take to discolour?

'30 minutes' ✓
What is the SA : V of this cube?

7 : 6

6 : 7 ✓

8 : 7

7 : 8
What is the relationship between the width of a cube and the surface area to volume ratio?

As the width of a cube doubles, the surface area to volume ratio also doubles.

As the width of a cube doubles, the surface area to volume ratio quadruples.

As the width of a cube doubles, the surface area to volume ratio halves. ✓

As the width of a cube doubles, the surface area to volume ratio triples.
As the SA : V increases, the time taken for a substance to diffuse will ...

'decrease' ✓
Which organism has the smallest SA : V?

cow ✓

mouse

human

ant

Worksheet

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Presentation

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Video

Lesson Details

Key learning points

The concepts of surface area, volume, and surface area to volume ratio.
Calculation of the surface areas, volumes and surface area to volume ratios of cubes of different sizes.
Use of coloured agar cubes of different sizes to observe time taken for acid to diffuse to the centre of each cube.
Interpretation of results and explanation using ideas about surface area to volume ratio and diffusion.

Common misconception

Mistakes with the calculations of surface area or volume are common. The concepts of surface area, volume and their ratio, with the effect that changing these have on diffusion, are difficult.

Plenty of practise on how to calculate surface area and volume, and compare these as a ratio, some simplified, is included. The experiment results are used to show the impact of changing surface area, volume and width on diffusion.

Keywords

Surface area - The total area of the surface of an object.
Volume - The total space of an object.
Surface area to volume ratio - The relationship between the surface area and the volume of a shape.
Diffusion - Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration.