BIOL 1010 Lecture Notes - Lecture 74: Phototropism, Houseplant, Wild Type
14 May 2017
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Experiments on how plant turn toward light led to the discovery of a plant hormone. The shoots of a house plant sitting on a windowsill grow toward light. If you rotate the plant, it soon reorients its growth until the leaves again face the window. Any growth response that results in plant organs curving toward or away from stimuli is called a tropism. the growth of a shoot in response to light is called phototropism. Phototropism has an advantage: directing growing seedlings and the shoots of mature plants toward the sunlight that drives photosynthesis. A hormone is a chemical signal produced in one part of the body and transported to other parts via circulatory system, where it acts on target cells to elicit a response. Like animals, plants also produce chemical signals that elicit effects on distant cells. Five major types of hormones regulate plant growth and development. Plant hormones are produced in very low concentrations.
