5.4 Plant Hormones Flashcards
what is a tropism?
a tropism is the response of a plant to a specific stimulus.
what is photostopism?
phototropism is the response of a plant’s shoot or root to light.
what is gravitropism?
gravitropism is the response of a plant’s shoot or root to gravity.
what is auxin?
auxin is a hormone which controls the growth of a plant’s shoots and roots. when auxin is unevenly distributed in a growing plant, the rate of growth will also be unequal.
how do plant shoots show positive phototropism?
- one side of the shoot is in the light, causing auxin to move to the shaded side.
- at the shaded side, the cells are stimulated to grow - the shoot bends towards the light.
- as a result, photosynthesis can occur at a faster rate.
how do plant shoots show negative gravitropism?
- in a horizontal shoot, auxin accumulates in the lower side due to gravity.
- cells on the lower side of shoot grow more, causing the shoot to bend away from the direction of gravity.
- as a result, more light is usually available for photsynthesis.
how do plant roots show positive gravitropism?
- in a horizontal root, auxin accumulates in the lower side, causing cells to grow less.
- the root bends in the direction of gravity.
- as a result, more water and nutrients are available to the plant roots.
what are gibberellins?
gibberellins are a type of plant hormone involved in seed germination.
what is ethene?
etheme is a type of plant hormone involved in cells division and ripening.
what are the uses of auxins?
- weedkillers - auxin causes cells to grow at a rapid rate, causing plant death.
- rooting powder - auxin causes new plant tol grow very quickly.
- tissue culture - auxin promotes growth of roots and shoots.
what are the uses of ethene?
control of food ripening in the food industry - allows fruit to be ripened just before they are sold.
what are the uses of gibberellins?
- termination of seed dormancy
- promotion of flowering
- increase of fruit size
