Plant Hormones Flashcards
Describe how plants are sensitive to light…
When a shoot tip is exposed to light, more auxin accumulates on side in shade, than side in light. This makes cell (elongate) faster on shaded side, so shoot bends towards light.
Describe how shoots grow away from gravity…
When a shoot is growing sideways, gravity produces unequal distribution of auxin in tip, more auxin on lower side. Causes lower side grow faster, bending shoot upwards.
Describe how roots grow towards gravity…
A root growing sideways will have more auxin on lower side. But in a root extra auxin inhibits growth. This means the cells on top elongate faster, and the root bends downwards.
Describe how roots grow towards moisture…
An uneven amount of moisture either side of root produces more auxin on side with more moisture. This inhibits growth on that side, causing root to bend in that direction, towards the moisture.
Explain what auxin is…
Auxin plant hormone controls growth near tips of shoots and roots. Controls growth of plant in response to light (phototropism), gravity (geotropism), and moisture. Auxin is produced in tips and moves backwards stimulate the cell elongation (enlargement) process occurs in cells just behind the tips. Extra auxin promotes growth in the shoot but inhibits growth in the root producing desired result.
Explain the uses of plant hormones in agriculture…
Most weeds in crop fields are broad-leaved, unlike grasses and cereals which have very narrow leaves. Selective weed killers are made of plant growth hormones - only affect broad-leaved plants. They disrupt their normal growth patterns, soon kills them, but leave crops untouched.
Explain plant hormones in horticulture…
Plant cuttings won’t always grow in soil. If rooting powder is added, which contains plant hormone auxin, produce roots rapidly and start growing as new plants. Helps growers to produce lots of clones of a really good plant very quickly.
