In general, foods are made up of carbohydrates, proteins, and fats, each of which provide a different number of calories: 1  Carbohydrates provide 4 calories per gram. 2  Proteins provide 4 calories per gram. 3  Fats provide 9 calories per gram.
Importance of Water. Water is used for various important purposes: Water in Agriculture. Water plays the most important role in agriculture. Agriculture is impossible without irrigation throughout the crop season. Irrigation ensures proper plant growth.
Water is of major importance to all living things; in some organisms, up to 90 percent of their body weight comes from water. Up to 60 percent of the human body is water, the brain is composed of 70 percent water, and the lungs are nearly 90 percent water. About 83 percent of our blood is water, which helps digest our food, transport waste, and control body temperature.