Grade 5 · Unit 1: Investigating plant growth
Plants and light
Plants make food from light – and grow towards it.
Making food from light
Green plants make their own food. This is called photosynthesis. Leaves use light, water and carbon dioxide to make sugar. They give out oxygen, the gas we breathe.
The sugar made in photosynthesis is used for energy and to build the plant. Some is stored as starch – in rice grains and potatoes, for example.
Why leaves are green
Leaves contain a green substance called chlorophyll. Chlorophyll traps the energy in light. Leaves are wide and flat to catch as much light as possible.
In autumn in colder countries, leaves stop making chlorophyll. The green fades, and yellow and red colours that were hidden show through.
Growing towards light
Plants grow towards light. This is called phototropism. A plant on a windowsill bends towards the window. Sunflowers turn their heads to follow the Sun.
The side of the stem in the shade grows faster than the side in the light. This makes the stem bend towards the light.
Light and life
Plants are the start of almost every food chain. Without plants making food from sunlight, animals and people would have nothing to eat.
Even the fish we eat depend on plants: tiny floating plants in the water are eaten by small animals, which are eaten by fish.
What I learnt
- I know that plants make food by photosynthesis using light.
- I know that plants grow towards light.