Modes of nutrition with special emphasis on human nutrition
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Modes of Nutrition
We all know that the plants can make their own food through the process of photosynthesis, however, animals and human beings cannot make food for themselves. They obtain food from plants and other animals that feed on plants. Thus, it is seen that human beings and animals depend on plants for their food – somewhere directly or indirectly.
Green plants are autotrophic and synthesize or make their own food by the process of photosynthesis. They do this with the help of carbon dioxide and water in the presence of sunlight. Photosynthesis is the process by which the green plants make their own food ( like glucose ) from carbon dioxide and water by using the sunlight energy in the presence of chlorophyll.
On the basis of their modes of nutrition, all the organisms are divided into two main groups – autotrophs and heterotrophs. Their corresponding modes of nutrition are known as the autotrophic and heterotrophic mode of nutrition.
Autotrophs (or Autotrophic Modes of Nutrition)
autotrophic modes of nutrition
Those organisms that can make food themselves from simple substances like carbon dioxide and water are called autotrophs. Their mode of nutrition is referred to as autotrophic. They do this by the process of photosynthesis.
All the green plants are called autotrophs. This is due to the fact that the green plants make their own food from very simple substances like carbon dioxide and water that is present in the surroundings. They do this by the process of photosynthesis.
We can also say that the green plants have an autotrophic mode of nutrition. These green plants contain a green pigment called chlorophyll which further helps in making food by absorbing energy received from the sunlight. Majorly the green plants synthesize their own food – not only for themselves but also for the non-green plants, animals as well as human beings.
Humans are omnivores, they can eat plant-based food as well as animal-based food.
Being more complex, humans have a very complicated nutrition system.
The digestive system has an alimentary canal and associated digestive glands, which together function to nourish the body.
There are five stages in human nutrition; Ingestion, Digestion, Absorption, Assimilation and Egestion.
Four stages i.e. ingestion, digestion, absorption and egestion take place in the alimentary canal while assimilation of food takes place in the whole body.