Class 10 Biology
Green plants 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: 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.
How do raw materials for photosynthesis become available to the plant?
- Water comes from soil; through the xylem tissue in roots and stems.
- Carbon dioxide comes in the leaves through stomata.
Significance of Photosynthesis:
- Photosynthesis is the main way through which the solar energy is made available for different living beings.
- Green plants are the main producers of food in the ecosystem. All other organisms directly or indirectly depend on green plants for food.
- The process of photosynthesis also helps in maintaining the balance of carbon dioxide and oxygen in the air.