Wondering Why?

Why do Leaves fall off Trees?

Why do Leaves fall off Trees?

Plants survive with the help of their food manufacturers, leaves. The leaves consist of a pigment called chlorophyll. This pigment gets excited by the photons released by the sunlight and gets reduced. The resultant reduced pigment in turn reduces adenosine di-phosphate (ADP) and Nicotinamide adenine di nucleotide phosphate (NADP) in a cycle. These reduced ADP and NADPH2 is called assimilatory power in the Light reaction of photosynthesis. This power is used in dark reaction part of photosynthesis to synthesize glucose molecules, which are essential for the survival of the plant.

As the summer gets away and days start to become shorter, autumn sets in. The sunlight available for the trees will be very meager. This will allow the tree to change the color of the leaves. The green pigment disappears as it cannot be used for food preparation for the whole autumn. The several inner metabolic changes make the leaves appear in various colors. These colors are given by the pigment called anthocyanin, which  is known to reduce the freezing point of the leaf and protect ti from shedding fast. Brown color is due to some wastes inside, yellow color is due to xanthophylls pigment and orange due to carotene pigment.

At these cold temperatures, the leaves can not endure the conditions and  due to a hormone called abscisic, acid gets cut at the base of it  which is attached to the tree. The reason why leaves fall off is to avoid losing much water in the plant due to the surrounding dry air. The water is stored in the plant where not much dry air can reach which may evaporate the water. The tree can no longer send the water and sap to the leaves from the roots. The tree prepares to tolerate the freezing conditions by shedding the leaves. This is for spending less energy to maintain the plant parts by shedding off the leaves. As the sun is also not available , it is not  necessary for the plant to have leaves to perform photosynthesis.


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1 User Submission

  1. it needs improovement, because the questionshould be answered at the beginning of the article so more readers will think that this website will answer more of their questions than others do. also start the article by restating the question. Hope this information will help improove this article and website!


    Ashcornel Brodyer.

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