which type of root are usually negatively geotropic? give one example
Answers
If you were to put a plant on its side, you'd notice that, after awhile, the roots would start growing downward while the stem would grow upward. This response to gravity is called geotropism, or gravitropism.
The roots are exhibiting positive geotropism, or growth with gravity, while the stem is exhibiting negative geotropism, or growth against gravity.
Different parts of a plant grow in opposite directions because they have different functions. The roots need to grow into the ground to provide stability for the plant, as well as to access water and nutrients. The stem needs to grow upward toward the sunlight so the plant can photosynthesize, or make food from sunlight.
So, how do different parts of a plant know which way to grow? Plants have organelles called statoliths, which settle at the bottom part of their cells and allow plants to sense gravity. They also have a hormone called auxin, which stimulates elongation and growth in plant cells. For root cells, the statoliths and auxin trigger downward growth, while cells above ground are signaled to grow upward.
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Answer:
pneumatophores are the respiratory roots in plants growing in marshy areas showing negative geotropism for gaseous exchange