What is Nutrition in Plants?
Nutrients in plants and animals, help in producing the energy required for the life process, offer growth and development of the body and help in the repair mechanism of the damaged parts of the body.
Nutrition can be simply defined as the process of nourishment obtained by taking in food by a living organism so as to assimilate the nutrients and utilize them for its own body. Plants make their own food with the help of sunlight, carbon dioxide, and water and hence are called autotrophs (auto–self, Trophos – nourishment). However, animals either depend on other small animals or plants for their food. Hence they are called heterotrophs (Hetero – other).
Why are plants so important for photosynthesis?
Photosynthesis is one of the best scientific discoveries made to date. Photosynthesis, as the name says, occurs in the presence of light (photo-light). It is a unique process where the energy captured from the sun is used for the preparation and storage of food in plants, indicating the sun is the main source of energy for all living organisms.
In plants, food is synthesized by the leaves and other green parts like the stems and branches of the plant. This is because they possess a green pigment, chlorophyll required for the photosynthesis process. Chlorophyll is responsible for capturing sunlight energy and transferring it to plants so as to use during the preparation of food. Leaves can also collect carbon dioxide from the air through tiny pores present on the surface of leaves. These pores called stomata, open only during the food-making process. Water and minerals present in the soil are absorbed by the root and conducted to the leaves by the stem.
During the photosynthesis process, water, carbon dioxide, and chlorophyll in the presence of sunlight synthesize carbohydrates and release oxygen into the atmosphere. Carbohydrates are stored in plants in the form of starch. This can be represented by an equation,
CO2 + Water + Chlorophyll Carbohydrates (C6H6O12) + oxygen
Other than carbohydrates, plants also produce proteins, which require nitrogen for synthesis. Nitrogen can be obtained from plants in the air but not in the same manner as carbon dioxide. Plant soils possess certain bacteria which convert the gaseous nitrogen present in the air to a soluble form that can be used by the plants. This is known as nitrogen fixation. Additionally, fertilizers and compost manures also contain nitrogen in soluble form to be used by the plants.
What are the Other modes of nutrition in plants:
Some plants lack the presence of chlorophyll pigment and hence they cannot prepare their own food. Such plants are heterotrophs and depend on their host plant for food. These plants derive nutrients from the trees they climb onto and hence are parasites of that tree. It is easy to find insectivorous plants in the forests, which depend on insects for their food.
These plants have a pitcher-like structure which is a modified part of the leaf (Figure 7.1.1). The apex of the leaf serves as a lid for the pitcher. Inside the pitcher, there are hairs running down. When an insect comes closer to the pitcher, the lid is shut down and the insect is pushed down the pitcher, resulting in the trapping of the insect. The insect is then digested by the pitcher with the help of digestive enzymes secreted by the pitcher.
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