Aadya Isai

Definition

Photosynthesis is the process by which green plants, algae, and some bacteria use light energy from the Sun to make food (glucose) from carbon dioxide and water.

It takes place mainly in the leaves of plants and is essential for all life on Earth because it provides food and oxygen.

Where Photosynthesis takes place and why?

Photosynthesis happens inside special structures in plant cells called chloroplasts.

Each chloroplast contains a green pigment called chlorophyll, which absorbs sunlight.

The leaves are the main organs of photosynthesis because:

• They have a large surface area to absorb more sunlight.

• They contain many chloroplasts.

• They have stomata (tiny pores) that allow gases

to move in and out.

Parts of the Leaf Involved:

1. Chloroplasts – Contain chlorophyll to capture sunlight.

2. Stomata – Tiny openings on the underside of leaves where carbon dioxide enters and oxygen exits.

3. Veins (xylem and phloem):

• Xylem brings water from the roots to the leaves.

• Phloem carries food (glucose) made in the leaves to other parts of the plant.

The Process of Photosynthesis (Step-by-Step)

1. Absorption of Light Energy:

Chlorophyll absorbs light energy from the Sun.

2. Splitting of Water (Photolysis):

The absorbed light energy splits water

molecules (H₂O) into hydrogen and oxygen

inside the chloroplast.

• Oxygen is released as a by-product into the air.

• Hydrogen is kept for the next step.

3. Formation of Glucose:

The hydrogen from water combines with

carbon dioxide (CO₂) taken from the air to form

glucose (C₆H₁₂O₆).

This process uses energy from sunlight.

4. Release of Oxygen:

Oxygen formed during the splitting of water

escapes through the stomata into the

atmosphere.