Describe Heterotrophic Nutrition ..
Answers
Heterotrophic Nutrition :
In heterotrophic mode of nutrition, organisms cannot prepare food their own. Heterotrophs obtain energy from organic molecule already produced by the autotrophs. For this, such organisms use bio catalysts called enzyme. The heterotrophic forms of nutrition differ in various organisms depending on the type, availability and process of obtaining food materials by an organism.
Accordingly, there are herbivores, carnivores, omnivores, saprotrophs, and parasites, included in heterotrophs.
Heterotrophic mode of nutrition are mainly three types :
- Holozoic nutrition : complex food molecules are taken in and then broken down into simpler and soluble molecules in this type of nutrition. Example - Amoeba, Human being, coe, goat, cat, dog. etc.
- Saprotrophic nutrition : Saprotrophs are the organisms which feed upon dead organic matter, these breaking down complex materials outside the body and absorbing. Examples - fungi like bread mould, mushrooms, yeast, bacteria.
- Parasitic nutrition : Parasites are the organisms having sch mode of nutrition. They either live inside or on the other living organisms (host) to obtain its nutrition without killing them. Examples - lice, yellow rattle, plant like Cuscuta etc.
Heterotrophic Nutrition:
It is a mode of nutrition in which the organisms obtain readymade organic food from outside sources.
The organisms that depend upon outside sources for obtaining organic nutritens are called heterotrophs. Heterotrophic nutrition is of three types – saprophytic, parasitic and holozoic.
Saprophytic or Saprotrophic Nutrition:
It is a mode of heterotrophic nutrition in which food is obtained from organic remains like dead organisms, excreta, fallen leaves, broken twigs, food articles, etc.
Organisms performing saprophytic nutrition are called saprophytes.
Parasitic Nutrition:
It is a mode of hetrotrophic nutrition in which a living organisms flourishes by obtaining food from another living organism.
The lving organisms which obtains food and shelter from another organism is called parasite.
The organism which provides food and shelter to a parasite is known as host. An external plant parasite is Cuscuta (Amarbel).
It is a non-green plant that sends haustroria or sucking roots into host plant for obtaining food and water.
Holozoic Nutrition:
It is a mode of heterotrophic nutrition which involves intake of solid pieces of food.
Since solid food is taken in, holozoic nutrition is also called ingestive nutrition.
The food may consist of another animal, plant or its parts.
Depending upon the source of food, holozoic organisms are of three types – Herbivores, carnivores, omnivores.