Chemical substances which provide energy to facilitate growth, repair and help to carry out various life processes are defined as nutrients. Nutrients are of 5 types: carbohydrates, proteins, fats, vitamins and minerals.

Good nutrition is essential for good health. Nutrition is defined as the process of taking in food and its utilisation by the body. It is provided by a number of nutrients like carbohydrates, proteins, fats, vitamins and minerals.

There are organisms, which can prepare their food from carbon dioxide and water in the presence of sunlight and chlorophyll. Organisms, which can make their own food by the process of photosynthesis are known as autotrophs. Autotrophs require the presence of sunlight, chlorophyll, water and carbon dioxide to make their food. Example- all green plants are autotrophs.

Organisms that depend on plants or other animals for their food are called heterotrophs. Different types of heterotrophic nutrition are: saprotrophic, parasitic, symbiotic and holozoic. These organisms are incapable of performing photosynthesis, and thus, they are dependent on autotrophs. Example- Humans and animals.

It is a green coloured pigment present in leaves of plants. It helps in the process of photosynthesis by which green plants can make their own food. It is present inside a cell organelle known as chloroplast.