Page 26 - 新思维科学学生用书9 样章

1.3 The carbon cycle

Returning carbon dioxide to the air

A lot of the carbon dioxide that plants take from the air eventually goes back into the air again. This
happens when plants and animals respire. You may remember the respiration equation:
glucose + oxygen → carbon dioxide + water

When you breathe out, carbon dioxide that was produced in your cells, by respiration, goes into the air
around you.

All organisms respire. Plants respire all the time. At night, when they cannot photosynthesise, they give
out carbon dioxide, just as we do.

Decomposers respire, too. As they break down waste products from plants and animals, they release
carbon dioxide into the air.

We can add this information to the flow diagram.

carbon dioxide
in the air

photosynthesis respiration respiration respiration

carbohydrates feeding carbohydrates
in plants in animals

feeding feeding

carbohydrates
in decomposers

25