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141  Take out the leaf and place it on a plate.  Now, put a few drops of diluted iodine solution with the help of a dropper on the decolourised leaf (Fig. 10.2b). Wait for a t few minutes and observe. l P  If the colour of the leaf changes to blue-black, it indicates the i presence of starch. e Caution —Alcohol should never be placed near a heat source directly, s c as it is highly ﬂammable and can easily lead to ﬁre and burns. r e L Did you wonder why we decolourise the leaf in the IVE D EEPER beginning of this activity? Decolourisation of a leaf enables us to easily observe colour change and, thus, the presence of starch. In Activity 10.1, we have learnt that water and sunlight are essential for plant growth. In Activity 10.2, we have discovered that green leaves store starch as food. Bhaskar loves gardening during his free time. Being a curious student, he often looks around his garden and wonders how plants produce food. From his experiences, Bhaskar knows that water and sunlight are essential for plant growth. But he wonders if sunlight contributes to the production of food in the form of starch in plants. How does sunlight contribute in the production of starch in plants? Activity 10.3: Let us check Bhaskar took a leaf having both green and non-green patches from each of two similar potted plants—one kept in sunlight and the other kept in the dark for 36 hours. He wanted to compare the leaves before and after the starch test. He made a sketch of the leaves to record the location of the green and the non-green patches on them with the help of a tracing paper. After that, he performed an iodine test (as shown in Activity 10.2) on the leaves. Bhaskar recorded his observations in Table 10.2. Reprint 2026-27