Explain the correlation between the original green area and the area stained by iodine.
The correct answer and explanation is:
The correlation between the original green area and the area stained by iodine is often used to assess the presence of starch in plant tissues. Iodine solution, when exposed to starch, causes a color change to a blue-black or dark purple, which indicates the presence of starch. In plant cells, starch is stored in the form of granules, and this staining reaction highlights where starch is concentrated.
The original green area refers to the part of the plant, such as the leaf, that was exposed to sunlight during the process of photosynthesis. The green color in leaves is due to chlorophyll, the pigment responsible for capturing light energy. Photosynthesis produces glucose, some of which is converted into starch and stored in the plant for later use.
When iodine solution is applied to a section of the plant, the areas that have stored starch will absorb the iodine and stain dark. The green area of the plant represents the portion where photosynthesis occurs and where starch is likely stored. Therefore, there should be a direct correlation between the green areas of the plant and the areas that stain with iodine, as these are the areas involved in starch production.
However, the correlation may not be perfect if some parts of the plant are exposed to less light or if starch is not uniformly stored. In such cases, the iodine staining will reveal a less uniform pattern of starch distribution. The more intense the staining, the higher the starch content, indicating more active photosynthesis and storage. Conversely, areas that do not stain or show weak staining may have lower starch concentrations, suggesting lower levels of photosynthetic activity.