Wednesday 26 January 2022

Nutrition in Plants (पौधों में पोषण) Full Chapter Class 7 Science | NCERT Science Class 7 Chapter 1

         Nutrition in Plants

What are nutrients?

carbohydrates, proteins, fats, vitamins and minerals are components of food. These components of food are called nutrients and are necessary for our body. 

Every living being required food, Plants can make their own food or synthesis, while animals and human being cant produce their food own, therefore animals and human directly or indirectly depends on plants for their food. 


Plants are only beings who make food by taking components from surroundings i.e water, crabondixiode, sunlights and other minerals from environments. 

Food is one way or mode by which living organisms take nutrition.The nutrients enable living organisms to build their bodies, to grow, to repair damaged parts of their bodies and provide the energy to carry out life processes.

Those living beings  who made their own food by taking components or simple substances from the environment are called autotrophic (auto = self; trophos = nourishment) nutrition. Therefore, plants are called autotrophs.

Animals and most other organisms take in food prepared by plants. They are called heterotrophs (heteros) = other.


Leaves are the food factories of plants. Therefore, all the raw materials must reach the leaf. Water and minerals present in the soil are absorbed by the roots and transported to the leaves.

Carbon dioxide from air is taken in through the tiny pores present on the surface of leaves. These pores are surrounded by ‘guard cells’. Such pores are called stomata.

Water and other minerals are transported through vessels inside the stems and roots to leaves.The leaves have a green pigment called chlorophyll. It helps leaves to capture the energy of the sunlight.

Since the synthesis of food occurs in the presence of sunlight, it is called photosynthesis.It is a unique process on the earth. The solar energy is captured by the leaves and stored in the plant in the form of food. Thus, the sun is the ultimate source of energy for all living organisms.

 Photosynthesis there would not be any food. The survival of almost all living organisms directly or indirectly depends upon the food made by the plants.Oxygen which is essential for the survival of all organisms is produced during photosynthesis, therefore without photosynthesis we can't imagine life on earth.

During the process oxygen is released. The presence of starch in leaves indicates the occurrence of photosynthesis. Starch is also a carbohydrate. 

Algae are green in colour. They contain chlorophyll which gives them the green colour. Algae can also prepare their own food by photosynthesis.

Synthesis of plant food other than carbohydrates

Carbohydrates  are used to synthesise other components of food such as proteins and fats. Plants synthesise carbohydrates through the process of photosynthesis.

Proteins are nitrogenous substances which contain nitrogen.These are absorbed by the plants along with water. farmers adding fertilisers rich in nitrogen to the soil. In this way the plants fulfil their requirements of nitrogen along with the other constituents.


There are some plants which do not have chlorophyll. They cannot synthesise food. Like humans and animals such plants depend on the food produced by other plants. They use the heterotrophic mode of nutrition. Example a plant named Cuscuta (Amarbel). It does not have chlorophyll. It takes ready-made food from the plant on which it is climbing.Cuscuta is called the parasite.

There are certain plants which can trap insects and digest them. A pitcher plant which has a pitcher-like or jug-like structure is the modified part of the leaf. A leaf above the pitcher acts as lid whenever any insect trapped inside that pitcher, which has hairs inside it which tanges the insect later digestive juices of the plant digest it. 

Such insect-eating plants are called insectivorous plants.


There are certain organisms which absorb the nutrients from dead and decaying matter called saprotrophic nutrition. Such organisms with saprotrophic mode of nutrition are called saprotrophs. 

Fungi is one example. Fungi also grows on bread, pickles, leather, clothes and other articles that are left in hot and humid weather for a long time. The fungal spores are generally present in the air. When they land on wet and warm things they germinate and grow.

Symbiosis-  It is a process of food sharing or food production where organisms live together and share both shelter and nutrients in exchange without harming each other.

For example, certain fungi live inside the roots of plants. The plants provide nutrients to the fungus and, in return, the fungus provides water and certain nutrients.


As we know plants and crops absorb nutrients like nitrogen, potassium, phosphorus,from soil to grow. While crops need much more nutrients from soils.

This continued farming and plantation growth sucks out the nutrients from plants. Therefore continued practise of adding nutrients to soil is very important like adding manure and fertilizers. 

Mainly nitrogen needs to replenish more for this, Farmers grow leguminous plants or crops like  gram, peas, moong, beans and other legumes to replenish nitrogen. Now the roots of these plants have a bacterium called Rhizobium.

Rhizobium cannot make its own food. So it often lives in the roots of gram, peas, moong, beans and other legumes and provides them with nitrogen. In return, the plants provide food and shelter to the bacteria. They, thus, have a symbiotic relationship. This association is of great significance for the farmers. 

Summary Ends

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