Write a note on modes of nutrition.

There are two modes of nutrition: autotrophic nutrition and heterotrophic nutrition.

(1) In autotrophic nutrition, the organisms prepare their own food through the process of photosynthesis in the presence of sunlight, carbon dioxide, water, minerals, and pigments such as chlorophyll, phycocyanin, phycoerythrin, etc.

(2) In heterotrophic nutrition, organisms depend on autotrophic organisms for their nutrition.

(i) Holozoic nutrition: It is the mode of nutrition that involves the ingestion, digestion, absorption, and assimilation of solid and liquid food materials to obtain nutrients.

(ii) Saprotrophic nutrition: In saprotrophic nutrition, organisms feed on dead or decaying organic material by secreting enzymes on it and absorbing nutrients.

(iii) Parasitic nutrition: It is the mode of nutrition where an organism derives its nutrition by harming or damaging another organism.