Nutrition In Plants

Science Class Seven

Evidence of Photosynthesis

In photosynthesis, plants prepare carbohydrate. Carbohydrate is ultimately converted into starch. The food prepared by plants stored in various parts of plants including leaves.

Thus, presence of starch in leaves confirms that photosynthesis takes place.

Photosynthesis in many non–green leaves

Leaves are of many colours. The leaves other than green also have chlorophyll. The large amount of brown and other pigment mask the green colour. Photosynthesis takes place in such leaves also.

class 7th science Nutrition in plants leaves of non green plants

Photosynthesis in Algae

Algae is a green coloured plant. Algae is generally found in stagnant water or algae may be grown up near places where always water is leaked or present in homes, such as near platform of tubewell, or in open balcony or on the roof near drain. Floor becomes slippery where algae are grown up.

class 7th science Nutrition in plants algae

Algae

Reference: By Vespertunes - Own work, CC BY-SA 4.0, Link

Since Algae is a green coloured plant, so, Photosynthesis takes place in it.

Synthesis of plant food other than carbohydrates

In the process of photosynthesis, plants make carbohydrates. Carbohydrates contains carbon, hydrogen and oxygen, which are used in making other components of food such as proteins and fats.

But in making of protein nitrogen is required also. Nitrogen is available in gaseous state in environment but plants do not absorb nitrogen from air.

How plant gets other minerals, like Nitrogen?

Plant absorbs nitrogen from the soil. Soil has certain bacteria that converts the gaseous nitrogen into a usable form and release it into the soil.

Sometimes farmers also add some fertilizer like Urea, which releases nitrogen, to the soil, to fulfill the requirement of additional nitrogen for the plants.

From the soil plants absorbs nitrogen along with water. Plants also absorb other minerals from the soil.

Other mode of nutrition in the Plants

Many animals and non green plants such as bacteria and fungi cannot prepare their own food for themselves. Non green plants depend on the food prepared by autotrophs. That is why plants and animals who do not make their food themselves are often referred as Nutritionally Dependent. Plants who do not make their food themselves and dependent on food made by green plants are called Heterotrophs. And this method of nutrition is known as Heterotrophic mode of nutrition.

Nutrition in non-green plants

Non green plants, such as Cuscuta do not have chlorophyll present in them. Cuscuta is known as Amarbel or Dodder also.

Since non green plants cannot make their food themselves, thus they take nutrition from other plants.

class 7th science Nutrition in plants cuscuta a parasitic plant

Cucuta: a parasitic plant

Reference: By Khalid Mahmood - Own work, CC BY-SA 4.0, Link

Cuscuta and other similar plants climb up on green plants and trees. These non green plants are called Parasites.

These plants are also referred as Parasitic Plant. Prasites depend for food on the other living organism.

Plants on which these non green plants grows and feed are called Host.

Cuscuta can be seen as rope like plants grow on the some big trees. In these types of plant a special root like structure grow, which is called Haustoria. These root like structures absorb food from the host plant (plant on which they grow). Since Dodder or Cuscuta is totally dependent on the host plant for their food, so, Dodder or Cuscuta is called the Total Parasite.

Mistletoe, which is found in Europe and in America, however, has green leaves. Mistletoe make its own food but it receives water and minerals from the host plant. So, Mistletoe is referred as Partial Parasite.

However, Mistletoe is a poisonous plant but it is used for decoration on the eve of Christmas.

Symbiotic Relation

In some cases two organisms live together and help each other. Such a relationship between two organisms, where both get benefited, is called Symbiotic Relationship.

Example

Lichen is a combination of Alga and Fungus. Algae is the plural form for Alga. Alga is an Autotrophs while Fungus is a Saprophyte.

Alga and Fungus live together. The fungus supplies water, minerals and salt to the Alga, whereas Alga supplies food after preparing it to the Fungus. In this example both alga and fungus get benefited.

Insectivorous Plant

Some plants feed on small insects and have developed special methods to capture their prey for food.

Plants which feed on small insects are called Insectivorous Plants.

Such plants being green are showing partly Autotrophic and partly Heterotrophic mode of nutrition.

These insectivorous plants normally grow in soil that is not so rich resulting they do not get complete nutrition from soil. So they use the nutrition obtained from insects to get the supplement of food they prepare by the process of photosynthesis.

Example: Pictcher plant, Wenus, Flytrap, Utricultaria, Drosera and Rafflesia etc.

class 7th science Nutrition in plants pitcher plant

Pitcher plants are carnivorous (animal eating) plants. Pitcher plants have prey-trapping mechanism. Pitcher plants have a deep cavity filled with liquid known as a pitfall trap. In pitcher plant leaf modified to form a pitcher like structure. These pitchers are attractive and of bright colour to attract the insects.

When an insect sits on the pitcher like structure, the lid closes and the insect get trapped inside the pitcher. The sides of the pitcher are slippery and may be grooved in such a way so as to ensure that the insects cannot climb out.

The insect is then digested by the enzymes present in the digestive juices secreted by the cell of the plant.

Cobra Lilies (Darlingtonia californica) is also an insectivorous plant. Cobra Lilies uses its window-like aeriolae to lure insects into their hollow leaves.

Do you know?

Rafflesia Arnoldii is a very interesting insectivorous plant as it bears the most gigantic flower in the world. Its diameter is around One meter (1 meter) and weight is upto 11kg. It was first discovered by Sir Stanford Raffles during his tour to Sumatra. This flower was named after him in his honour.

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