Class 10 Science

Life Processes: Plant Nutrition

In this section, you will learn about the basic concept of photosynthesis. You will learn about key steps of photosynthesis and raw materials required for photosynthesis. You will also learn about various experiments which can be conducted to show if photosynthesis took place in a plant. Moreover, you will learn about significance of photosynthesis.

These notes are based on the chapter Life Processes from class 10 science NCERT book and CBSE syllabus.

  • Photosynthesis
  • Steps of photosynthesis

Green plants are called autortophs because they prepare their own food. They make food in the presence of sunlight. Sunlight provides energy. Carbon dioxide and water are the raw materials. Chloroplast is the site where food is made. Photosynthesis generally takes place in leaves. It also happens in other parts which are green.


The process by which green plants prepare food is called photosynthesis. During this process, the solar energy is converted into chemical energy and carbohydrates are formed. Green leaves are the main sites of photosynthesis. The green portion of the plant contains a pigment chloroplast, which contains chlorophyll. The whole process of photosynthesis can be shown by following equation:

6CO2 + 6H2O ⇨ C6H12O6 + 6O2

Steps of Photosynthesis:

  • Sunlight activates chlorophyll, which leads to splitting of water molecule.
  • The hydrogen, released by splitting of water molecule is utilized for reduction of carbon dioxide to produce carbohydrates.
  • Oxygen is the byproduct of photosynthesis.
  • Carbohydrate is subsequently converted into starch and is stored in leaves and other storage parts.
  • The splitting of water molecules is part of the light reaction.
  • Other steps are part of the dark reaction during photosynthesis.

Dark reaction does not mean that it happens during darkness. It just means that dark reaction does not need light. In some desert plants, carbon dioxide is taken up at night. This is utilised to make an intermediary, which is later utilised to make carbohydrate.


Raw materials for photosynthesis

  • Water comes from soil, through the xylem tissue in roots and stems.
  • Carbon dioxide comes in the leaves through stomata.

Cross Section of Leaf

Cross Section of Leaf

Fig Ref: NCERT Textbook Class 10 Science

This figure shows cross-section of leaf. The upper epidermis is continuus while lower epidermis has gaps due to presence of stomata. It is the lower epidermis which faces the sunlight. You can see small dots in cells of mesophyll. These dots are chloroplasts. The cells of mesophyll, thus, are the sites for photosynthesis.

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