Answer :
Answer:
To replenish nutrients in the soil, various natural processes occur. One common way is through the decomposition of organic matter. When plants, animals, or other organisms die, their remains decompose, releasing nutrients back into the soil. Additionally, weathering of rocks and minerals also contributes to the release of nutrients into the soil. Plant roots play a vital role in absorbing these nutrients and then, when the plant dies or sheds leaves, the nutrients return to the soil.
The process of photosynthesis is essential for plants to produce their food. During photosynthesis, plants use sunlight, water, and carbon dioxide to create glucose (a type of sugar) and oxygen. The process involves two main stages: the light-dependent reactions that occur in the thylakoid membranes of chloroplasts and the light-independent reactions (Calvin cycle) that occur in the stroma of chloroplasts. In simple terms, plants use sunlight to convert carbon dioxide and water into glucose, which is used as energy for the plant.
To test the presence of starch in leaves, you can perform an iodine test. Iodine solution turns blue-black in the presence of starch. Here's how you can do it:
1. Take a leaf and boil it in water to soften it.
2. Place the leaf in a test tube and cover it with alcohol (e.g., ethanol).
3. Heat the test tube in a water bath until the leaf loses its green color.
4. Rinse the leaf with water to remove alcohol.
5. Add a few drops of iodine solution to the leaf.
6. If the leaf turns blue-black, it indicates the presence of starch.