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Plants are producers: they make their own food. Animals are consumers: they depend on plants, either by eating them or by eating animals that ate plants.

The process is called photosynthesis ('putting together with light'). In words: carbon dioxide + water → glucose + oxygen, powered by light energy.

It happens mainly in the leaves, inside tiny green parts of the cells called chloroplasts. The green pigment chlorophyll traps the light.

Experiment: The coloured-water flower

1. Add 20 drops of food colouring to one glass of water. Leave the other glass plain as a control.
2. Ask an adult to cut the bottom 1 cm off the stems, so the tubes are fresh.
3. Stand one flower or celery stick in each glass.
4. Check after 1 hour, 4 hours and 24 hours. Where does the colour appear first?
5. Next day, an adult cuts across the celery stem. Look at the cut end with a magnifying glass: can you see coloured dots?

Time	Coloured water: what I see	Plain water: what I see
1 hour	How long will it take for the colour to reach the top? Make a guess.
4 hours	How long will it take for the colour to reach the top? Make a guess.
24 hours	How long will it take for the colour to reach the top? Make a guess.

Questions

1. Write the word equation for photosynthesis.

2. Explain how water gets from the soil to a leaf. Use the words roots, xylem and transpiration.

3. What happened to your flower in coloured water? Why did we also use a glass of plain water?

4. Draw a leaf and label: chloroplasts (inside the cells), stomata, and the veins.

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Sources for every fact on this sheet: echoesof.science/school/plants/sources/

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