Light Is Essential for Photosynthesis

Photosynthesis is a fundamental biological process that occurs in plants, algae, and some bacteria, enabling them to convert light energy from the sun into chemical energy in the form of glucose and other organic molecules. During photosynthesis, plants use sunlight, water, and carbon dioxide to produce glucose (a simple sugar) and oxygen. External factors affecting photosynthesis include light, carbon dioxide concentration, temperature, and water availability.

Light is essential for photosynthesis because it provides the energy necessary to drive the chemical reactions that convert carbon dioxide and water into glucose and oxygen.

To demonstrate the experiment on light is essential for photosynthesis, we need to follow the given procedure:

• Firstly, we will take a destarched plant and cover part of a leaf with black paper strips using clips.
• Now, we will keep this plant in bright sunlight for two hours.
• Next, boil water in a beaker and let it cool to around 60°C.
• After two hours, we will pluck the leaves, remove the black paper, and put them in hot water to soften.
• Transfer the softened leaves to a boiling tube with alcohol.
• Now, put the boiling tube in the hot water beaker until the leaves become colourless.
• Next, we will take the iodine solution in a petri dish and add the washed leaves in it.
• After about five minutes, take out the leaves, wash them, and observe the colours of the exposed and covered parts.

This experiment demonstrates that the covered leaf part remains brown (no starch), while the exposed part turns blue-black (starch presence) with iodine. This confirms light’s necessity for photosynthesis, as it initiates and sustains complex reactions. Light acts as the catalyst, unique to plants, in producing their own food and driving energy flow in ecosystems, supporting growth and life on Earth.

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