Biology iGCSE: How Plants Use Glucose

For Respiration

1) Plants manufacture glucose in their leaves. 2) They then use some of the glucose for respiration. 3) This releases energy which enables them to convert the rest of the glucose into various other useful substances, which they can use to build new cells and grow. 4) To produce some of these substances they also need to gather a few minerals from the soil.

For Making Proteins

Glucose is combined with nitrate ions (absorbed from the soil) to make amino acids, which are then made into proteins.

For Making Cell Walls

Glucose is converted into cellulose for making strong cell walls, especially in a rapidly-growing plant.

For Storing in Seeds

Glucose is turned into lipids (fats and oils) for storing in seeds. Sunflower seeds, for example, contain a lot of oil - we get cooking oil and margarine from them. Seeds also store starch.

For Storing as Starch

Glucose is turned into starch and stored in roots, stems and leaves, ready for use when photosynthesis isn't happening, like in the winter. Starch is insoluble which makes it much better for storing s glucose- a cell with lots of glucose in would draw in loads of water and swell up. Potato and parsnip plants store a lot of starch underground over the winter so a new plant can grown from it in the following spring. We eat the swollen storage organs.