explain about phototropism
Answers
What is Phototropism?
If you put a plant in a window, you may notice that, after a few days, it has bent toward that window. This is because the plant needs sunlight to make energy, so it grows toward the light. The growth of a plant toward any stimulus is called tropism, and the growth of a plant toward a light stimulus is called phototropism - photo means light.
Seedlings of plants grow straight upward in dark environments in order to reach the sunlight above ground. Once they break through the surface, they start bending toward the light because the growth of cells on the dark side is faster than the cells on the light side. However, if the amount of light is the same on all sides of the plant, then it will continue to grow straight upward instead of bending.
Early Experiments on Phototropism
Early experiments on phototropism were based on the idea that plants were bending toward the warmth of the light, not necessarily the light itself. Charles Darwin performed many experiments in the late 1800s, and his results showed that photoreceptors, which are cells that detect light in the tip of the plant, communicated to the lower part of the plant that curves. From this, he concluded that there must be some substance produced in the tip of the plant that is sent to the lower part of the plant, signaling it to bend.
Darwin's work eventually led to the discovery of a plant hormone called auxin.
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Answer:
Explanation:
→ Phototropism is the growth of a plant in the direction of its light source. Plants are very sensitive to their environment. A tropism is the growth of a plant as a response to a stimulus, and phototropism occurs when a plant responds to light by bending in the direction of the light. Plant hormones called auxins play an important role in phototropism. Auxin is a plant growth hormone. When light falls on one side of a plant, the auxins move to the dark side of the plant. The hormones stimulate the cells on the dark side of the plant to elongate, while the cells on the light side of the plant remain the same. This elongation on one side and staying the same on the other causes the plant to bend in the direction of the light.