Plants for food

Undoubtedly, the most important use of plants is for food. Almost everything you eat is either from plants, or is a result of plants. As plants lock the sun's energy in the bonds of glucose molecules, this building block can be used by humans and all animals for food and energy.

Glucose is essentially sugar, and is made up of elements like carbon, hydrogen and oxygen. When these glucose molecules link together in long chains, they form the insoluble carbohydrate storage unit called starch.

Starch is stored by the plant as an energy reserve, although we simply think of it as food. Potatoes, rice, pasta and bread are all starch and are basically our main sources of energy.

Our body breaks starch down into glucose again to be used for respiration.

Plants can't survive on starch alone. Like us, they require amino acids to make proteins for growth and repair, and fats as an energy storage, or in the case of plants, as oil, seeds and nuts.

While carbohydrates, oil and fats are made of carbon, hydrogen and oxygen, proteins require an additional element: nitrogen. Plants uptake this predominantly in the form of nitrates in the soil. They take in nitrates through their roots, along with phosphates and sulphate.

Basically, with a few added nutrients, glucose created during photosynthesis is the basis for all other organic substances, and is the source of all of our food.