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What is Autotrophic Nutrition? Life processes Class 10 Science

Autotrophic Nutrition Life processes Class 10 Science

What is Autotrophic Nutrition? Life processes Class 10 Science

Here we will learn about Autotrophic Nutrition from CBSE Class 10 Science – Life Processes.

What is Nutrients?

What Is Nutrition?

Autotrophic Nutrition

The nutrition in which organisms prepare their own food from inorganic raw materials like carbon dioxide and water is called autotrophic nutrition.

Autotrophs: The organisms which can make their own food are called autotrophs (green plants).

Photosynthesis: The process by which green plants make their own food with the help of CO2 and H2O in the presence of chlorophyll and sunlight is also called photosynthesis.

Raw Materials for Photosynthesis:

The site of Photosynthesis: Chloroplast in the leaf. Chloroplast contains chlorophyll. (green pigment).

Main Events of Photosynthesis


Events of photosynthesis

  • Chlorophyll absorbs light energy.
  • Light energy is converted to chemical energy.
  • Water molecule splits into hydrogen and oxygen.
  • Carbon dioxide reduces to carbohydrates.
  • Green dots present in some cells of leaves are called chloroplasts which contain chlorophyll.

Fig. chloroplast

  • The site of photosynthesis in a cell of the leaf is chloroplasts.
  • The plants obtain carbon dioxide by tiny pores called as stomata present on the surface of the leaves of plants.
  • The carbon dioxide gas enters the leaves through the stomata.
  • Stomatal pores are surrounded by a pair of guard cells and guard cells regulate opening and closing of stomata.


Fig. opening and closing of stomata

Functions of Stomata

  • (i) Exchange of gases

(ii) Loses a large amount of water [water vapor] during transpiration and helps in up flow of water

  • Water can be lost through stomatal hence the pores are closed when not needed for photosynthesis.
  • When water flows into guard cells this swell causing the stomatal pores to open and the pores close if the guard cells shrink.
  • The raw materials such as water, nitrogen, phosphorous etc. used in photosynthesis are also taken up by the plants from different sources.
  • Water is absorbed by plants from the soil by the roots in terrestrial plants.
  • Nitrogen, phosphorous, iron, magnesium is taken up from the soil.
  • Nitrogen is either taken in the form of inorganic nitrates or as organic compounds prepared by bacteria from atmospheric nitrogen.
  • Nitrogen is used in the synthesis of proteins.

Fig. roots absorb nutrients and water from the soil

  • During photosynthesis carbon dioxide and water are used to convert into carbohydrate.
  • Light energy is trapped by chlorophyll and with the help of carbon, dioxide carbohydrate is prepared.
  • Plants manufacture all the other organic substances that they need from these carbohydrates and very small quantities of minerals from the soil.
  • It is the process of converting light energy into chemical energy and storing it in the bonds of sugar.
  • This process occurs in plants and some algae. Plants need only light energy, CO2 and H2O to make sugar.
  • The process of photosynthesis takes place in the chloroplasts, where the pyruvate breaks down to give carbon dioxide and water with the release of energy.
  • The total energy fixed is around 1% of the total energy. Photosynthesis takes place primarily in plant leaves and in stems.
  • The parts of a typical leaf include the upper and lower epidermis, the mesophyll, the vascular bundle, and the stomata.
  • The upper and lower epidermal cells do not have chloroplasts, thus photosynthesis does not occur there.
  • They serve primarily as protection for the rest of the leaf. The stomata are holes, which are in the lower epidermis and are used for air exchange.
  • The vascular bundles or veins in a leaf are a part of the plant’s transportation system which transports water and nutrients for the plant as needed.
  • The mesophyll cells have chloroplasts and this is where photosynthesis occurs.
  • Collect three or four green leaves of any common plant such as spinach or radish and crush them with a grinding stone.
  • Put this crushed pulp on a piece of white paper. A green patch will be formed on the paper. This is formed due to the pigment called chlorophyll.
  • The molecule of chlorophyll pigment present in organelles called chloroplasts has the unique property of trapping solar energy which is then utilized for the synthesis of food in the chloroplast.
  • You will recall that white light consists of a range of wavelengths of light known as VIBGYOR. Maximum absorption of the red and blue wavelengths of the spectrum takes place due to chlorophyll. Photosynthesis is most efficient in these ranges of light. Chlorophyll reflects back the green wavelength and hence it appears green in color. Chlorophyll consists of four pigments.
  • These are chlorophyll a and b which are green. The other two are xanthophylls and carotene which are yellow and orange, respectively. The overall green color of the leaf is because of the predominance of the green pigments.

Watch and Learn how photosynthesis process work through visualization, Click CBSE Class 10 Science for demos.

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For more articles and videos for 10 Science click below

Life Process

Nutrition in Plants

Excretion in Plants 

Transportation in Plants

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