AQA Biology 4.4.1.1

Photosynthesis

A plant makes its own food from air, water and light. Bring the three together in a leaf cell and watch what comes out.

Triple Science · Higher tier

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The cupboard plant.

A houseplant is left in a dark cupboard for a few weeks while its owners are away. When they get back, it is pale and drooping.

If you had to guess, is that because it needs light, or because it needs fresh air?

Inside a leaf cell

Photosynthesis happens in the chloroplasts, where chlorophyll absorbs light. Send in each raw material, and the light. Then switch the light off.

Send in carbon dioxide, water and light.

How fast this happens, and what limits it: in Rate of photosynthesis.

The equation

Learn the word equation. Light is written over the arrow: it supplies the energy, it isn’t a reactant.

carbon dioxide + water light glucose + oxygen

Photosynthesis is endothermic: energy is transferred from the environment to the chloroplasts by light. Recognise the symbols: tap each.

What the plant does with the glucose: in Uses of glucose.

Think again · food from the soil

“Plants get their food from the soil.”

Your call

Choose

Where does a plant’s glucose come from?

Sort

Place each one.

Tap a card, then tap the box it belongs in. Tap a placed card to take it back.

Command words in this lesson

Key fact

Carbon dioxide + water, with light, gives glucose + oxygen. It is endothermic and happens in the chloroplasts.

Key note · AQA 4.4.1.1

Photosynthesis: carbon dioxide + water, with light, gives glucose + oxygen.
It happens in chloroplasts, where chlorophyll absorbs light.
It is endothermic: energy is transferred from the environment to the chloroplasts by light.
Recognise the symbols CO₂, H₂O, O₂ and C₆H₁₂O₆. Photosynthesis needs light; respiration happens all the time.

Photograph this card. Tomorrow, cover it and say each line first.

Not sure why light isn’t a reactant?

The leaf cell is schematic.