biochemistry, Science and Environment

Leaf color transition during fall season

We all know that in autumn and/or fall season, the leaves start to change color from green to red, yellow, and brown. The mixture of red, purple, orange and yellow is the result of chemical processes that take place in the tree as the seasons change from summer to winter. My 5-year-old kid always ask me “Why and how do leaves change colors during fall?”
To explain this, let us first understand the function of leaves. The food-making process takes place in leaves in numerous cells containing chlorophyll, which gives the leaf its green color. Chlorophyll has a vital function: it captures solar rays and uses the resulting energy in the manufacture of the plant’s food — simple sugars which are produced from water and carbon dioxide. These sugars are the basis of the plant’s nourishment — the sole source of the carbohydrates needed for growth and development. In their food-manufacturing process, the chlorophyll break down, thus are being continually “used up”. During the growing season, however, the plant replenishes the chlorophyll so that the supply remains high and the leaves stay green.


How plants make food during fall season without chlorophyll pigments?
During fall, because of changes in the length of daylight and changes in temperature, the leaves stop their food-making process. The chlorophyll breaks down, the green color disappears, and the yellow to orange colors become visible.

The steps below describe how the leaves change color during fall/autumn season:

Growing season of plants

Color of leaves are green due to chlorophyll pigments

Fall/autumn season

Lack of sunlight energy

Degradation of chlorophyll pigments

The pigments carotenoids and anthocyanins that have been present (along with the chlorophylls) in the cells all during the leaf’s life begin to show through. These provide colorations of yellow, brown, orange, and purple colors, respectively.

A fun and educational video by SciShow Kids explains why do leaves change color in fall?

I have mentioned below a science experiment that describe the leaf color changing phenomenon in detail.

Suggested science experiment books 

Leaves change color
Science detectivesbooks

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