Seven Science    

Nutrition in Plants   Quiz
Nutrition in Animals    QnA   Quiz
Fibre to Fabric  QnA   Quiz
Heat    QnA    Quiz
Acid Base & Salt  QnA  Quiz  
Changes  QnA  Quiz
Weather&Climate  QnA   Quiz
Wind,Storm&Cyclone   QnA  Quiz
Soil     QnA     Quiz
Respiration In Organisms   QnA    Quiz
Transportation in Organisms  QnA   Quiz
Reproduction in Plants    Quiz
Motion & Time    QnA   Quiz
Electric Current    QnA      Quiz
Light    QnA      Quiz
Water   QnA   Quiz
Forest: Our Lifeline    QnA   Quiz
Wastewater    QnA     Quiz

Nutrition in Plants


Food is the most important and basic thing for life. Carbohydrates, proteins, fats, vitamins and minerals are the components of food. These components are necessary for all living beings. All plants and animals require food for their growth and getting energy. The process of utilization of food by an animal to obtain energy for growth and development is known as nutrition. Plants make their food themselves but animals cannot. Hence, animals depend directly or indirectly on the plant.


1. What are the components of food?

Answer – Carbohydrates, proteins, fats, vitamins and minerals are the components of food.

2. What is nutrition?

Answer – The process of utilization of food by a living organism to obtain energy is called nutrition.

3. Why is need of nutrition?

Answer – Animals do not make their food themselves which plants do. Animals eat plants or plant eating animals. Hence, animals are directly or indirectly depend on plants.

Mode of nutrition in plant

Autotrophic Nutrition -

Auto means self and trophos means nourishment. Plants are called autotrophs because they make their food themselves. The making of food for themselves is called the Autotrophic nutrition. Autotrophic nutrition is found in green plants.

Heterotrophic Nutrition –

The word Heterotrophic is the combination of two words i.e. Hetero + Trophos. Hetero means ‘others’ and ‘trophos’ means nourishment. If organisms depend on others for their food, it is called the Hetetrophic Nutrition.

Animals cannot make their food themselves. They depend for food upon plants. Therefore, nutrition in animals is called Hetetrophic Nutrition. Animals are known as Heterotrophs.

Saprotrophic Nutrition

The taking of nutrients by organism from dead and decaying matter in the form of solution is called the saprotrophic nutrition. The organisms which use saprotrophic mode of nutrition are called saprotrophs. For example: fungi.

Questions – 1: What is autotroph?

Answer- Organisms that make their food themselves are called autotrophs.

Question-2: What is autotrophic mode of nutrition?

Answer: The mode of nutrition in which the organism makes its own food is called autotrophic mode of nutrition.

Question -3: Give some example of autotrophs.

Answer: All green plants, such as grass, mango, bougainvillea, etc. are the examples of autotrophs.

Question-4: What is heterotrophic mode of nutrition?

Answer: The mode of nutrition in which an organism takes food from another organism is called heterotrophic mode of nutrition. The nutrition in animals and non-green plants is the example of heterotrophic mode of nutrition.

Question-5: Give examples of Heterotrophs.

Answer: Animals and non green plants are the examples of heterotrophs.

Question-6: What is saprotrophs?

Answer: Plants which get their nutrition from dead or decaying plants in liquid form are called saprotrophs.

Photosynthesis - Food Making Process in Plants

The process of making of food by green plants in the presence of sunlight and chlorophyll is known as photosynthesis.

Photosynthesis is the combination of two words- Photo + Synthesis. ‘Photo’ means light and ‘Synthesis’ means to make.

Process of food making in green plants:

Green plants make their food themselves. Green leaves make food from Carbon dioxide and water in the presence of sunlight and chlorophyll.

Hence, for taking place of photosynthesis carbon dioxide, water and sunlight must be reached at the green leaves in addition to presence of chlorophyll.

Leaves have several tiny pores like structure on its lower surface. This is called stomata through which leaves absorb carbon dioxide from air. Water is transported to the leaves through hair like pipelines from the roots. These pipelines are present throughout the plant, i.e. from roots to branches and leaves. These pipe-lines are known as Xylem. Xylem is a type of tissues. Chlorophyll, a green pigment, is found in green leaves. Chlorophyll absorbs sunlight and gives energy. Chlorophyll absorbs sunlight, carbon dioxide and water and convert them to carbohydrate and oxygen. Carbohydrate is used as food and oxygen is emitted out to atmosphrere.This whole process of making food by plants is called photosynthesis.

The reaction takes place in the process of photosynthesis can be written as:

 photosynthesis reaction

Carbohydrate which is produced in the process of photosynthesis is ultimately converted into starch and stored into leaves. From leaves it is transported to the parts of plants. Starch is a type of carbohydrate. The oxygen so produced is released into atmosphere through the stomata.

Leaves are known as the kitchen or food factories of the plants because photosynthesis takes place in leaves. Leaves look green because of the presence of chlorophyll.

Besides leaves, photosynthesis takes place in other green parts of the plant also, such as in green stems. Chlorophyll is necessary for photosynthesis; hence photosynthesis takes place only in green plants.

The leaves of plants that grow in desert areas are modified in spine like structure or scales to reduce the loss of water in the course of transpiration. In such plants photosynthesis takes place in green stems.

The photosynthesis helps to maintain a balance between oxygen and carbon dioxide in the atmosphere as it absorbs carbon dioxide and release oxygen.

Sunlight is necessary for photosynthesis. Thus sun is the ultimate source of energy for all living organism.

Our earth is the only unique planet, where photosynthesis takes place. In the absence of photosynthesis life would not be possible on earth.

Following are necessary for photosynthesis to be taken place:

• Presence of sunlight

• Presence of Chlorophyll

• Presence of Water

• Presence of carbon-dioxide

Photosynthesis in Algae –

Green patches in ponds or near the stagnant water can be seen easily. These green patches are living organism called algae. Algae are plants. Often algae grow near the shallow waterlogged areas such as near tube-wells, taps, etc. One may slip over it. Algae look green because of presence of Chlorophyll. Algae prepare their own food by the process of photosynthesis.

Questions- 1 - What is photosynthesis?

Answer- The process of making food in green plants in the presence of sunlight is known as photosynthesis.

Questions- 2 - What are the essentials factors for the photosynthesis?

Answer - Carbon dioxide, water, chlorophyll and sunlight are essentials factors for the photosynthesis to take place.

Question – 3 - What is chlorophyll?

Answer- Chlorophyll is the green pigment present in green leaves.

Question – 4 – Why do leaves look green?

Answer – Leaves look green because of the presence of chlorophyll, which is a green pigment.

Questions- 5: What is the function of chlorophyll?

Answer - Chlorophyll absorbs the sunlight for photosynthesis.

Question – 6: What are the final products made after photosynthesis?

Answer- Glucose and oxygen are the final products after photosynthesis.

Questions – 7: What are stomata?

Answer- The small pores present on the lower surface of leaf, are called stomata.

Questions- 8: What is function of stomata?

Answer - Stomata absorb carbon dioxide from air for photosynthesis.

Question - 9: What is the ultimate source of energy?

Answer – Sun is the ultimate source of energy.

Question – 10: How water is transported to the leaves?

Answer: Water is transported to the leaves through pipe like structures from the roots of plant. These pipe-like structures are present from root to leaves through branches throughout.

Synthesis of plant food other than carbohydrate

Plants need proteins and fats besides the carbohydrate. Proteins are nitrogenous substances which contain nitrogen. Although nitrogen is present in abundance in atmosphere, but plant cannot absorb atmospheric nitrogen. Plant gets nitrogen from soil. Certain types of bacteria called rhizobium, are present in soil. They convert gaseous nitrogen into usable form and release it into the soil. Plants absorb these soluble forms of nitrogen along with water and other minerals through their roots.

Sometimes farmers add nitrogenous fertilizer to their field to fulfill the need of nitrogen. In this way plants gets fulfillment of nitrogen along with other nutrients. After the fulfillment of all nutrients plants synthesise proteins and fats.

Question: 1 – What are the nutrients other than carbohydrates which are required by plants?

Answer: Proteins and fats are the nutrients; other than carbohydrates; which are required by plants.

Question: 2 – In which form do plants absorb nitrogen?

Answer: Plants absorb soluble form of nitrogen.

Question: 3 – Why do farmers add nitrogenous fertilizers to the soil?

Answer: Farmers add nitrogenous fertilizers to the soil to fulfill the requirement of nitrogen of the plants. Nitrogen is necessary to synthesise proteins.

Question: 4 – Which microorganism help to provide nitrogen to the plants?

Answer: A certain type of bacteria called rhizobium help to provide nitrogen to the plants.

Question: 5 – How do plants absorb nutrients other than carbohydrates from the soil?

Answer: Other nutrients are available in the soil in the form of minerals. Plants absorb these minerals from the soil; along with water.


Some plants do not have the chlorophyll. Hence, they cannot synthesise their food by themselves. Such plants are known as non green plants. They depend on other organisms for food. Such plants use the heterotrophic mode of nutrition. Some of them are called parasite. A parasite is an organism which lives on or inside the body of another organism and takes shelter and food from that organism. The host; in this case; is always at loss.

Plants that do not have chlorophyll are called non-green plants. Plants, which live on other plants for food, are called parasitic plants.

Parasite (Parasitic Plant):

Plants that get their food from other plants by living on them are called parasite. Example; Cuscuta, mistletoe.

Cuscuta is a vine like plant with yellowish stem. It twines around big trees, like banyan tree. Cuscuta gets nutrition from the tree on which it lives. The tree upon which it climbs and lives is called the host. Here, banyan is the host and cuscuta is the parasite.

Some plants are total parasite while some are partial parasite.

A total parasite fully depends on other plants for their nutrition. For example - cuscuta.

Partial parasite -

Partial parasite is a parasite that receives a part of its nutrients from host. For example; mistletoe bears green leaves. It synthesises its own food, but receives water and mineral from host plant.

Question: 1 – What do you understand by parasitic plants?

Answer: A plant which lives on another plant and takes nutrients is called a parasitic plant.

Question: 2 – Give some example of parasitic plants.

Answer: Cuscuta and mistletoe

Question: 3 – Why some plants are called parasites?

Answer: Some plants are unable to prepare their own food and need to take food from another plant. Hence, they are called parasites.

Question: 4 – What is the mode of nutrition in non-green plants?

Answer: Non-green plants show heterotrophic mode of nutrition.

Question: 5 – What do you understand by non-green plants?

Answer: A plant which lacks chlorophyll is called non-green plant.

Question: 6 – What do you understand by host?

Answer: An organism which provides shelter and nutrition to another organism is called a host.

Question: 7 – What is partial parasite?

Answer: A parasite which depends for some of the nutrients; on another organism; is called a partial parasite.

Question: 8 – Give example of partial parasitic plants?

Answer: Misteltoe

Insectivorous plant –

Some plants eat insects. Such plants are called insectivorous plants. They trap and digest the insects. Pitcher plant is the example of an insectivorous plant. In pitcher plant the leaf is modified to form a pitcher like structure. The bright colour of the pitcher makes it very attractive to insects. Inside the pitcher; there are several hair-like structures. These hairs direct the trapped insects downwards. When an insect sits on the pitcher of the plant, the lid closes and the insects get trapped inside the pitcher. The insect is then digested by the enzymes secreted by the cells of the plants.

Cause of eating of insects by plants: The soil of marshy land is deficient in nitrogen. Plants living in marshy areas do not get nitrogen from the soil. Their nitrogen need is fulfilled by sucking the juice of insects. Venus flytrap, utricularia, drosera and Rafflesia are the other examples of insectivorous plants.

Question: 1 – What is an insectivorous plant?

Answer: A plant which fulfills its nitrogenous needs by eating insects is called an insectivorous plant.

Question: 2 – Give an example of insectivores plant?

Answer: Pitcher plant, Venus Fly trap, Bladderwort, Drosera, Rafflesia

Question: 4 – Why does a plant eat insects?

Answer: Plants living in marshy areas do not get nitrogen from the soil. To fulfill their nitrogenous need, they need to eat insects.

Question: 5 – Write a brief note on pitcher plants?

Answer: In a pitcher plant, the leaf is modified into a pitcher like structure. The pitcher is complete with a lid. The inside of pitcher is full of hair-like structures. The pitcher is used to trap insects which may fall in it.

Saprotrophs –

Saprtrophs are non-green plants e.g. Agaricus (Mushroom) fungi, yeasts and bacteria. Saprotrophs get their food from dead or decaying organic matters. They grow on decaying organic matters such as cow-dung, wood, bread, etc.

Saprotrophs secrete digestive juice over the decaying materials and absorb nutrients from them. This is called Saprotrophic Mode of Nutrition. Such plants are called saprotophs.

Question: 1 – What do you understand by saprotrophs?

Answer: An organism which feed on dead and decaying material is called a saprotroph. In this mode of nutrition, digestive enzymes are secreted on the food. The digested food is then absorbed by the organism. In saprotrophs digestion takes place outside the body of the organism.

Question: 2 – Saprophytes grow in which type of places?

Answer: Saprophytes grow in humid and hot conditions.

Question: 3 – Give some example of saptrotrophs.

Answer: Mushroom, yeast, toadstool, etc.

Symbiosis or mutualism –

Symbiosis is the combination of two Greek words ‘Sym’ menas ‘with’ and ‘biosis’ means ‘living’, which means living together. In symbiosis or mutualism two different types of organisms live and work together for their mutual benefit from each other. They share shelter and nutrients, e.g. Lichens. Lichens are composite organisms composed of fungus and alga. Fungus is a saprophyte and alga is an autotroph. The Fungus supplies water and minerals to the cells of the alga while the alga supplies food; prepared by photosynthesis.

A bird sitting on the back of a rhino is an example of symbiosis. The bird gets worms to eat, while the rhino gets rid of those worms.

Replenishment of Nutrients in Soil -

Some fungus live in the roots of the plans. Roots of the plants provide shelter and food to the fungus while fungus provides important nutrients to the plants.

Because of continuous farming nutrients keep declining in the soil. Hence, to replenish those nutrients fertilizers are added to the soil.

Plants require a lot of nitrogen to grow and to be healthy. Although, a lot of nitrogen is available in the atmosphere, but plants cannot absorb nitrogen in gaseous form. There is a bacterium called Rhizobium, which lives in the root nodules of legumes, such as gram, moong, etc. These bacteria can absorb nitrogen from the atmosphere and make it available for the plants. Rhizobium cannot make its food, hence, it provides nitrogen to the legumes and in return legumes provide them food and shelter. This is an example of symbiotic relationship. This has great importance for farmers. Fields in which leguminous plants are grown from time to time, do not need addition of nitrogenous fertilizers.

Question: 1 – What is the meaning of word ‘Symbiosis’?

Answer: It is a relationship between two organisms in which both the organisms benefit each other.

Question: 2 – What is Lichen?

Answer: The lichen is a composite organism formed because of symbiosis of algae and fungi.

Question: 3 – Give an example of symbiotic relationship.

Answer: A small bird; called plover; cleans the crocodile’s teeth. The crocodile keeps its mouth open and the bird takes out meat fibres stuck between the teeth. The bird gets food in lieu of providing dentist’s services to the crocodile.

Question: 4 – How do nutrients get replenished in the soil?

Answer: There are two main means through which nutrients get replenished in the soil. One of them is the nitrogen fixation in soil. Nitrogen fixation replenishes nitrogenous nutrients in the soil. Another mean is decomposition of dead remains of plants and animals (or farm waste). Decomposition of dead remains replenishes various other nutrients in the soil.

Question: 5 – What is Rhizobium?

Answer: Rhizobium is a bacterium.

Question: 6 – What is the function of Rhizobium?

Answer: Rhizobium helps leguminous plants in nitrogen fixation in soil.

Question: 7 – How does Rhizobium help farmers?

Answer: By helping in nitrogen fixation, rhizobium increases soil fertility and thus helps farmers.

Question: 8 – Why do farmers prefer to sow leguminous plants?

Answer: Leguminous plants carry out nitrogen fixation in soil and thus improve soil fertility.

Question: 9 – In which form do plants absorb nitrogen?

Answer: Plants absorb nitrogen in the form of nitrates.


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