Leaves come in various colours but most often they are green. Do you know why the leaves of almost all plants are found in this colour? We know that the colour of any substance depends upon its property of absorption and reflection of the different colours of light. The leaves of the plant appear coloured due to the presence of some specific substances in them. For example, the presence of chlorophyll makes them appear green while the presence of carotene makes them yellow. When the leaf contains more than one substance, the colour is a mixture. The leaves, which contain both chlorophyll and carotene, appear yellowish-green. New leaves of some plants contain a red substance called anthocyanin, which gives the pink or red colour to the tender leaves. With the passage of time, chlorophyll and carotene are formed in these leaves, which ultimately turns them green. The structure of chlorophyll molecules is such that when the sunlight (mixture of seven colours) falls on them, they reflect the green colour and absorb the rest. It is this green light that is visible and makes the leaf green. Plants synthesise their food with the help of chlorophyll in the presence of the sunlight, carbon dioxide and water. This process is called ‘photosynthesis‘. Plants without chlorophyll, like fungi, cannot make their own food. They depend on other living beings. Such plants are called parasites. So, you see chlorophyll is a very important substance for plants. Apart from imparting the green colour to them, chlorophyll also helps a plant to synthesise food.
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