Gas Exchange and Stomata — Revision Notes | KS3 Biology

Brain dump

Before you look at anything else, write down everything you can remember about this lesson: key words, facts, examples. Spelling doesn't matter. Then see which of the 9 key terms you remembered.

2:00

Everything you remember

Key terms

Photosynthesis: How a plant makes its own food
Glucose: A type of sugar that the plant uses to grow and survive
Gas exchange: The leaf taking in carbon dioxide and releasing oxygen
Stomata: Small holes in the surface of a leaf
Guard cells: Cells that change shape to open and close stomata
Water vapour: Water in its gas state
Diffusion: Particles spreading out because of their random movement
Concentration gradient: A difference in how crowded particles are between areas
Net movement: More particles moving from high to low concentration

What this lesson covers

How well do you know each one? Be honest: red means go back over it.

Explain why a photosynthesising leaf must take in carbon dioxide and release oxygen
Describe how gases pass through stomata into the air spaces inside a leaf
Explain how guard cells open and close the stomata
Outline the trade-off between letting carbon dioxide in and losing water
Suggest why many cacti open their stomata at night
Explain how diffusion moves carbon dioxide into a leaf and oxygen out

Test yourself

Cover the answer, say it out loud, then check the full quiz on the lesson page.

Which gas do leaves take in for photosynthesis?
Which of these does NOT pass through open stomata?
In a photosynthesising leaf, what is the net movement of carbon dioxide?

Topic quiz

20 questions on this topic only — not mixed with anything else, one at a time.

Question 1 of 20

Spelling challenge

Read the definition, then type the correct spelling of the term. Uses the same terms as above.