For your growth group

How a leaf eats light

Photosynthesis, Grade 10 Life Sciences. Questions for a midweek discussion, drawn from the lesson, approved before publishing.

One. The question

If the mass does not come from the soil, where does a 500kg tree get 500kg from?

Two. The ingredients

Which gas goes in, and through which structures does it enter the leaf?
What is the pathway water takes from the soil to the leaf?
Is light a raw material or an energy source, and how can you tell?

Three. The kitchen

Where exactly in the cell does photosynthesis take place?
If a leaf looks green, which colours of light is it using, and which is it wasting?

Four. The equation

Name two different things a plant does with the glucose it makes.
Where does the oxygen given off actually come from: the carbon dioxide or the water?

Five. The exam

With no food being made, what runs out first, and what does that do to the plant?

For personal reflection at home

Completely lost

Start with just that one sentence, nothing else. Air (carbon dioxide) plus water, powered by light, becomes sugar. Get that solid and every detail hangs off it.

Getting there

You have the idea; now lock the equation. The numbers matter in the exam, and they balance for a reason.

Test on Friday

Friday's paper will not ask you to list ingredients. It will remove one (light, water, or carbon dioxide) and ask what happens and why. Practise the removing.

Want to go deeper

If the basics are solid, go here: chlorophyll absorbs red and blue and reflects green, which is why plants are green and why grow-lights are often purple. The colour is a clue to the chemistry.

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