It is the process by which an organism acquires food. Two major types of nutrition are Autotrophic and heterotrophic nutrition.
These are the organisms that can make their food themselves. They can prepare organic food from inorganic substances. Autotrophic mode of nutrition further includes Photoautotrophic and chemoautotrophic modes of nutrition.
- Photoautotrophic organisms carry out photosynthesis. For example plants use CO2 and water in the presence of sunlight to make glucose (food).
- Chemoautotrophic organisms get their energy from a chemical reaction and use CO2 as the carbon source. The inorganic energy source can be ferrous iron, hydrogen, hydrogen sulfide etc. Some bacteria are chemoautotrophic.
These are the organisms that cannot make their own food but feed on other organisms.
It includes Holozoic, saprotrophic and parasitic modes of nutrition.
- Holozoic mode of nutrition includes the organism taking food by ingestion(by mouth)
- Parasitic mode of nutrition includes a feeding mode in which one organism lives on the body or inside the body of the other organism(host) and derives its nutrients from there. Such an organism is a parasite. Parasites harm the hosts. For example, mosquitoes are parasites. Lice is another example.
- Saprotrophic mode of nutrition includes organisms feeding on dead decaying organic matter/plant or animal bodies. Most bacteria and fungi are saprotrophic.