Nutrition in plants

• Green plants are autotrophic and synthesize their own food by the process of photosynthesis.
• The process, by which green plants make their own food from carbon dioxide and water by using sunlight energy in the presence of chlorophyll, is called photosynthesis.
• Oxygen is released during photosynthesis.

The process of photosynthesis can be represented as:

• The process of photosynthesis takes place in the green leaves of a plant.
• The food is prepared by the green leaves of a plant in the form of simple sugar called glucose.
• The extra glucose is changed into another food called starch. This starch is stored in the leaves of the plant.
• The green plants convert sunlight energy into chemical energy by making carbohydrates.

The photosynthesis takes place in the following three steps:

1. Absorption of sunlight energy by chlorophyll.
2. Conversion of light energy into chemical energy, and splitting of water into hydrogen and oxygen by light energy.
3. Reduction of carbon dioxide by hydrogen to form carbohydrate like glucose by utilizing chemical energy.

Conditions necessary for photosynthesis:
The conditions necessary for photosynthesis to take place are:

1. Sunlight
2. Chlorophyll
3. Carbon dioxide
4. water

• Green leaves make starch as food. Starch gives a blue-black color with iodine solution.

Raw materials for photosynthesis:
The raw materials for photosynthesis are:

1. Carbon dioxide
2. Water

How the plants obtain carbon dioxide?

• There are a large number of tiny pores called stomata on the surface of the leaves of plants.
• The carbon dioxide gas enters the leaves of the plant through the stomata present on their surface.
• Each stomatal pore is surrounded by a pair of guard cells. The opening and closing of stomatal pores is controlled by the guard cells.
• When water flows into the guard cells, they swell, become curved and cause the pore to open.
• On the other hand, when guard cells lose water, they shrink, become straight and close the stomatal pores.

How the plants obtain water for photosynthesis:

• The water required by the plants for photosynthesis is absorbed by the root of the plants from the soil through the process of osmosis.
• The water absorbed by the roots of the plants is transported upward through the xylem vessels to the leaves where it reaches the photosynthetic cells.

1. The plants also need other raw materials such as nitrogen, phosphorus, iron, and magnesium, etc., for building their body.
2. The plants take these materials from the soil.
3. Nitrogen is an essential element used by the plants to make proteins and other compounds