Plant hormones Flashcards
What is auxin
A plant hormone that controls growth near the tips of shoots and roots
What does auxin do
It controls the growth of a plant in response to light (phototropism) and gravity (geotropism)
Where is auxin produced
In the tips
Where does auxin move too in plants
It moves backwards to stimulate the cell elongation process which occurs in the cells just behind the tips
What happens if the tip of a shoot is removed
No auxin is available and shoots may stop growing
What does extra auxin do
Promotes growth in the shoot but inhibits growth in the shoot
What do shoot grow towards
LightLight
What do shoots grow away from
Gravity
What do roots grow towards
Gravity
What happens when shoots grow towards light
-when a … is … to light more … accumulates on the … that’s in the … than the side that’s in the …
-this makes the … grow faster on the … side so the … bends … the light
-this makes the … grown faster on the shaded side so the shoot bends towards the light this makes the … grow … on the … side so the … bends … the …
-when a shoot is exposed to light more auxin accumulates on the side that’s in the shade than the side that’s in the light
-this makes the cells grow faster on the shaded side so the shoot bends towards the light
-this makes the cells grown faster on the shaded side so the shoot bends towards the light this makes the … grown faster on the shaded side so the shoot bends towards the light
Why do shoots grow away from gravity, and roots grow towards gravity
-when a … is growing …, … produces an … distribution of … in the tip, with … auxin on the … side
-this causes the … side to grow …, bending the shoot …
-a … growing … will also have … on its lower side
-but in a root … auxin … growth so the … on top … faster and the … bends …
-when a shoot is growing sideways, gravity produces an unequal distribution of auxin in the tip, with more auxin on the lower side
-this causes the lower side to grow faster, bending the shoot upwards
-a root growing sideways will also have auxin on its lower side
-but in a root extra auxin inhibits growth so the cells on top elongate faster and the root bends downwards
Plant growth response practical, investigating the effect of light on growth
- Put … cress … into three different … dishes, each lined with … filter …, and … your dishes eg A, B, C
- Shine a … onto one of the … from …, 2 from different …
- Leave the … seeds for a … until you can … their …
- You should … that the seedling grow … the …
- … variable: … of seeds, … of seed, t.., v… of w…, l… i…
- Put 10 cress seeds into three different Petri dishes, each lined with moist filter paper, and label your dishes eg A, B, C
- Shine a light onto one of the dishes from above, 2 from different directions
- Leave the cress seeds for a week until you can observe their responses
- You should observe that the seedling grow towards the light
- Control variable: number of seeds, type of seed, temp, volume of water, light intensity
Uses of auxins
Killing …:
-they … normal … patterns
Growing from … with … powder:
-… powder contains …
-if u put a … in … with rooting … they will produce … and start growing …
-produces …
Growing … in tissue …
-grow … of a … from a few …
-… are added to the … medium to … cells to … forming root and …
Killing weeds:
-they disrupt normal growth patterns
Growing from cuttings with rooting powder:
-rooting powder contains auxins
-if u out a cutting in soil with rooting powder they will produce roots and start growing rapidly
-produces clones
Growing cells in tissue culture
-grow clones of a plant from a few cells
-auxins are added to the growth medium to stimulate cells to divide forming root and shoots
Uses of Gibberellin in controlling dormancy:
-lots of … won’t … until they have been … certain …
—>this is called …
-seeds can be … with … to alter …
-making them … at times of … they wouldn’t …
Controlling dormancy:
-lots of seeds won’t germinate until they have been through certain conditions
—>this is called dormancy
-seeds can be treated with gibberellin to alter dormancy
-making them germinate at time of year they wouldn’t normally
Use of gibberellin in inducing flowering
-some … require certain … to … eg low …, longer …
-if these plants are … with gibberellin they will … without any … in their …
-can also be used to … bigger …
-some plants require certain conditions to flower eg low temps, longer days
-if these plants are treated with gibberellin they will flower without any change in their environment
-can also be used to grow bigger flowers
Using gibberellin to grow larger fruit
-… varieties of … often don’t grow as … as … fruit
-if … is added to these … they will grow …
-seedless varieties of fruit often don’t grow as large as seeded fruit
-if gibberellin is added to these fruits they will grow larger
Uses of gibberellin
-c… d…
-i… f…
-g… l… f…
-controlling dormancy
-inducing flowering
-growing larger fruit
What does ethene do
Stimulates the ripening of fruit
How does ethene simulate the ripening of fruit
-Ethene is a … produced by … parts of a …,
-it influences … of the plant by … cell …
-it … enzymes that cause the … to …
-Ethene is a gas produced by aging parts of a plant,
-it influence growth of the plant by controlling cell division
-it stimulates enzymes that cause the fruit to Ripen
How can ripening be delayed
-by adding … that … ethene’s … on the … or … the amount of … the fruit can …
-by adding chemicals that block ethene’s effect on the fruit or reduce the amount of ethene the fruit can produce
Summary of the uses of auxins, gibberellin, ethene
Auxins:
-killing weeds
-growing from cuttings with rooting powder
-growing cells in tissue culture
Gibberellin:
-controlling dormancy
-inducing flowering
-growing larger fruit
Ethene:
-ripening fruit
