Plants make their own food by photosynthesis in chloroplasts. The word equation is: carbon dioxide + water → glucose + oxygen, using light energy. Carbon dioxide enters leaves through tiny pores called stomata, and water comes up from the roots. Glucose is used for respiration, stored as starch, or turned into cellulose and proteins.
All living cells respire to release energy. Aerobic respiration is: glucose + oxygen → carbon dioxide + water. It is roughly photosynthesis in reverse. Plants respire all the time, day and night, but in bright light they photosynthesise faster, so they take in carbon dioxide overall. Light, carbon dioxide and temperature can all limit the rate of photosynthesis.
Worked example
Why does a plant give out carbon dioxide at night?
- At night there is no light, so no photosynthesis.
- Respiration still happens in every cell.
Answer:Respiration produces carbon dioxide, so the plant gives it out.
Key words
- photosynthesis
- making glucose from carbon dioxide and water using light
- glucose
- a sugar made in photosynthesis
- stomata
- tiny pores in leaves for gases
- aerobic respiration
- releasing energy from glucose using oxygen
New questions every time.
NGSS-referenced: MS-LS1-6