Photosynthesis and Respiration: Two Halves of One Cycle

0:00How are photosynthesis and respiration linked? Look at two tiny parts of cells.

0:06A chloroplast is where photosynthesis happens. Chloroplasts are found in plant cells.

0:13Photosynthesis uses energy from sunlight to make food.

0:18The reactants, the substances that go in, are carbon dioxide and water.

0:25The products, the substances made, are glucose, a sugar, and oxygen.

0:31A mitochondrion is where most cellular respiration happens.

0:36This is aerobic respiration: it uses oxygen to release the energy stored in glucose.

0:43Its reactants are glucose and oxygen, the products of photosynthesis.

0:49Its products are carbon dioxide and water, the reactants of photosynthesis.

0:54The products of each process are the reactants of the other, so together they form one cycle.

1:01Atoms of carbon and oxygen go round and round this loop, used again and again. Matter cycles.

1:09Cells use the energy from respiration, and in the end it leaves as heat.

1:16Energy comes in as light and leaves as heat, so energy flows through.

1:22A common myth is that plants make oxygen only for animals.

1:27But plant cells have mitochondria too, so plants use oxygen for respiration, day and night.

1:34Photosynthesis and respiration are two halves of one cycle: matter cycles, while energy flows through.