Studied by 0 peopleWhat is a tropism?
The response of a plant to a specific stimulus.
What is phototropism?
The response of a plant’s shoot or root to light.
What is gravitropism?
The response of a plant’s shoot or root to gravity.
What is auxin?
A hormone which controls the growth of a plant’s shoots and roots. When it’s 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 the 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 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?
A type of plant hormone involved in seed germination.
What is ethene?
A type of plant hormone involved in cell 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 plants to 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.
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