The process by which all living organisms obtain and take food, utilize the food to carry out various life processes is called nutrition.
Plants are the only living organisms on Earth that are capable of preparing their own food through the process of photosynthesis. A green color pigment called chlorophyll present in the leaves traps light energy from Sun. Raw materials i.e carbon dioxide and water are then converted into simple foods called carbohydrates.There are 2 major modes of nutrition in plants. These are:
1. Autotrophic Nutrition
The mode of nutrition in which living organisms make food for themselves by using simple substances is known as autotrophic nutrition ('auto' means self and 'trophos' means nourishment). Plants which are capable of preparing their own food are called autotrophs.
2. Heterotrophic Nutrition
The mode of nutrition in which the living organisms obtain food from other living things i.e plants is called heterotrophic nutrition ('hetero' means others and 'trophos' means food). Animals cannot prepare their own food and hence get their food from the plants. Animals are called heterotrophs.
Photosynthesis - the food making process in plants
The leaves of plants are called the food factories as food for the plant is prepared here. Root hairs of the plants absorb water and minerals from the soil and transport these to the leaves. Tiny pores called stomati (sl. stomata) present under the surface of the leaves take in carbon dioxide from the air. Stomata is surrounded by guard cells.