Nutrition
Nutrition in Plants
All living beings need food to carry out various life processes. Food gives living beings the material to build and maintain their body.
Nutrition is the process by which an organism obtains its food and utilize them. The nutrition can be categorised mainly into two type's namely autotrophic and heterotrophic nutrition.
Autotrophic Nutrition
Autotrophic organisms make their own food from simple raw materials available in their environment. Green plants, algae and some bacteria can produce their own food by the process of photosynthesis. The process of photosynthesis occurs only when plants or algae or some bacteria have green pigment, called chlorophyll in their cells. In the process of photosynthesis, the leaves of plants convert water and carbon dioxide into glucose or sugar and oxygen with the help of energy from the sun. Plants take in carbon dioxide from air and water from the soil.
Heterotrophic Nutrition
The plants which do not contain chlorophyll obtain their food by heterotrophic mode of nutrition. There are mainly three types of plants which obtain their food by heterotrophic nutrition. These plants are:
Saprophytic plants
Saprophytes are the non-green plants that feed on dead and decaying organic matters derived from plants and animals. These organisms break down the organic matters by secreting digestive juices into it. For example, mushrooms and toadstool, etc.
Parasitic plants
Some non-green plants live inside or on other organisms and derive nutrition from them. Such plants are called parasites and the organisms on which the parasite lives are called hosts. For example, dodder is a parasitic plant that winds its yellowish and threadlike stems around other plants and draw nutrition from them.
Insectivorous plants
Some plants obtain a part of their food from insects. For example pitcher plants trap the insects in their modified leaf, kill them and digest them to obtain nutrients. In fact insectivorous plants grow in the soil which is not very rich in nutrients. So they get essential nutrients by eating insects.
Nutrition in Animals
Animals cannot make their own food because they do not have green pigment named chlorophyll. Animals depend on plants or other animals for their food.
Nutrition in Animals involve Five Steps
Ingestion: Intake of food inside the body is called ingestion.
Digestion: Breaking down of large food molecules to smaller one is called digestion.
Absorption: The digested food is absorbed into blood stream through intestinal wall. This process is known as absorption.
Assimilation: The process of utilizing absorbed food by body cells for various metabolic processes is called assimilation.
Egestion: The process of removing undigested food out
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