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Question
Name the phenomenon occurring in plants which are under the control of gravity, water and chemicals with one example each that shows the movement involved.
Solution
A plant always grows its roots downward in reaction to gravity. Geotropism is the name given to this occurrence. A plant root will always gravitate towards water in response to it. The name for this occurrence is positive hydrotropism. During fertilisation, the ovule releases chemicals that cause the pollen tube to expand in the direction of the ovule, a phenomenon known as chemotropism.
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