1.     All living organisms require food as a source of energy.
2.    Nutrients:  carbohydrates, proteins, fats, vitamins and minerals are the components of food. These components of food are necessary for our body and are called nutrients.
3.     Nutrition: It is the mode of taking food by an organism and its utilization by the body.
4.      Autotrophic: The mode of nutrition in which organism make food themselves from simple substances is called autotrophic (auto = self, trophos = nourishment) nutrition Therefore, green plants are called autotrophs.
5.     Heterotrophs: The category of organisms that take readymade food prepared by the plants are called heterotrophs (heteros = other, trophos = nourishment). For example: Human animals etc.
6.     Parasitism plants: Some plants take readymade food from other organism and harms them. Such plants are called parasites and the organism, that suffers are called host. For example: Cuscuta is a parasite.
7.     Saprotrophs: The category of organism that take nutrients from dead and decaying matter are called saprotrophs and the mode of nutrition is called saprotrophic nutrition.
8.     Symbiotic relationship: Some organism live together for their mutual advantage. This is called symbiotic relationship. For example: Lichens. In lichens, a chlorophyll containing partner which is an alga, and a fungus live together.
9.     Insectivorous plants: Some plants trap the insects and eat it that come in their contact. Such insect eating plants are called insectivorous plants. For example: pitcher plant.
10.  Photosynthesis:
             i.  It is food making process in plants.
            ii.  The synthesis of food in plants occurs in all the green parts of it, especially leaves.
          iii.  During photosynthesis, chlorophyll containing cells of leaves in the presence of sunlight, use carbon dioxide and water to synthesis carbohydrates.
   Carbon dioxide + water        ------------->           Carbohydrate + Oxygen
            iv.Stomata: These are the tiny pores present on the surface of the leaves. These pores are surrounded by ‘guard cells’. Such pores are called stomata.
11.  Sun is the ultimate source of energy for all living organisms.
12.   We have to add ferilizers and manures to soil from time to time to enrich the fertility of soil that increases the production of crops.
13.   Cholorophyll: A green plant pigment which absorb energy from sunlight, enabling the plant to build up food as carbohydrates from carbon dioxide and water by photosynthesis.
14.   Host: A plant or an animal that supports a parasite is called host.