plant hormones Flashcards
what is a tropism?
a tropism is the response of plants to a specific stimulus
what is phototropism?
the response of a plant’s shoot or root to light
what is geotropism?
geotropism is the response of a plant’s shoot or root to gravity
what is auxin?
a hormone which controls the growth of a plants shoots and roots. When the 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 shoot bends towards the light
- as a result, photosynthesis can occur at a faster rate
how do plant shoots show negative geotropism?
- 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 photosynthesis
how do plants show positive geotropism?
- 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?
a type of plant hormone involved in seed germination
what is ethene?
a type of plant hormone involved in cell division and ripening of fruits
what are the uses of auxins?
- as weed killers- auxin cause cells to grow at a rapid rate, causing plant death
- as rooting powder- auxin causes new plant to grow very quickly
- for promoting growth in tissue culture- auxin promotes growth of roots and shoots
what are the uses of ethene?
control of food ripening in the food industry- allow fruit to be ripened just before they are sold
what are the uses if giberrillins?
- end seed dormancy
- promote flowering
- increase fruit size.
