Depending upon the source of energy briefly explain different modes of nutrition.

Dear student
Basically, there are two modes of nutrition.

Autotrophic Nutrition:-The mode of nutrition in which organisms manufacture their own food using inorganic components like water and carbon dioxide as well as sunlight as the source of energy is known as autotrophic mode of nutrition. For example- Green plants

 

Heterotrophic Nutrition:- The mode of nutrition in which the organism cannot make their own food, they are dependent on plants and other animals for nutrition, it is known as heterotrophic mode of nutrition. For example- animals. 

There are four types of heterotrophic mode of nutrition:

  • Holozoic mode of nutrition: The mode of nutrition in which food is taken in solid/liquid form from outside and is digested inside their body, this mode of nutrition is known as holozoic mode of nutrition. For example: Humans.
  • Parasitic mode of nutrition: The mode of nutrition where the organism lives in or on the other organism and derive its food from the body of the host is called parasitic mode of nutrition. For example: Cuscuta.
  • Saprophytic mode of nutrition: The mode of nutrition in which the organism takes nutrients in solution from dead and decaying matter is called saprophytic nutrition. For example: Mushrooms.
  • Symbiotic mode of nutrition: The mode of nutrition in which organisms live in association with other plants or animals and share their resources. In this kind of relationship, both the partners are benefitted by the relationship. For example: Lichen- an association between algae and fungi.
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Dear student,
 

Broadly, there are two types of nutrition among living organisms, namely:

  • Autotrophic mode
  • Heterotrophic mode

Autotrophic Nutrition

In the autotrophic mode, organisms use simple inorganic matters like water and carbon dioxide in the presence of light and chlorophyll to synthesize food on their own. In other words, the process of photosynthesis is used to convert light energy into food such as glucose. Such organisms are called autotrophs. Plants, algae, and bacteria (cyanobacteria) are some examples where autotrophic nutrition is observed.

During photosynthesis, carbon dioxide and water get converted into carbohydrates. These carbohydrates are stored in the form of starch in plants. Plants later derive the energy required from the stored starch. The process of photosynthesis can be explained in three stages:

  1. Absorption: The chlorophyll present in leaves traps the light coming from the sun.
  2. Conversion: The absorbed light energy gets converted into chemical energy. And water absorbed will split into hydrogen and oxygen molecules.
  3. Reduction: At last, carbon dioxide gets reduced i.e. hydrogen molecules combine with carbon, to form carbohydrates (sugar molecules).
Nutrition

Autotrophic Nutrition

Photosynthesis

All three events are not a continuous process. They may or may not take place sequentially.

In plants, stomata are the openings on leaves where gaseous exchange takes place and is regulated by guard cells. Plants take in and release gases through these stomatal pores.

In desert-like habitats, to avoid water loss, guard cells keep these pores closed during the daytime. Later, during the night time, stomata will be opened to absorb carbon dioxide and store in the vacuoles. During the daytime, they will use this stored carbon dioxide to perform photosynthesis.

Other than photosynthesis, plants also depend on soil for micro and macro elements. These elements are used to synthesize proteins and other essential compounds required for the proper functioning and growth of the plants.

Also Read: Nutrition in Animals

Heterotrophic Nutrition

Nutrition

Heterotrophic Nutrition

Every organism is not capable of preparing food on its own. Such organisms depend on others for their nutrition. The organisms which cannot produce food on their own and depend on other sources/organisms are called heterotrophs. This mode of nutrition is known as heterotrophic nutrition.

Fungi and all the animals including humans are heterotrophs. Heterotrophs can be of many varieties depending upon their environment and adaptations. Some may eat plants (herbivores) and others eat animals (carnivores) while few eat both (omnivores). Thus we can say survival of heterotrophs depends directly or indirectly on plants.

Heterotrophs are classified into different categories based on their mode of nutrition. They are:

  • Parasites (e.g. leeches, ticks)
  • Saprophytes (e.g. mushrooms)
  • Holozoic (e.g. humans, dogs)
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