Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIO > Plant responses > Flashcards

Plant responses Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

Why must plants be able to respond to stimuli?

A

To avoid herbivory.
To respond to abiotic stress.
To access resources.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is a nastic movement?

A

A fast, non-directional movement such as a venus fly trap closing.
Also folding in response to touch (mimosa pudica)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are some physical plant defences against herbivory?

A

Spikes, thorns, stings.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are some chemical defences against herbivory?

A

Tannins.
Alkaloids.
Pheromones.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are some examples of alkaloids and how do they protect the plant?

A

Caffeine and nicotine are alkaloids, they affect the metabolism of insects.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What are tannins and how do they protect the plant?

A

Bitter tasting phenols.

Toxic to insects.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

How can pheromones be used to protect the plant?

A

Allows the plant to communicate with itself and other plants to prepare for attack in response to herbivory.
Deter insects.
Plants can also produce pheromones that attract beneficial organisms to protect the plant.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are tropisms?

A

Permanent responses to a directional external stimulus that result in growth towards (positive tropism) or away (negative tropism) from the stimulus.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How does phototropism affect the shoots and roots of a plant?

A

Shoots are positively phototropic.

Root are negatively phototropic.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the mechanism by which phototropism works?

A

Auxin is redistributed to the dark side of the shoot tip, the auxin diffuses down the stem to the zone of cell elongation. The higher auxin concentration causes cells on the dark side to elongate more, causing the stem to grow toward the light.
Roots have the opposite response to auxin. (auxin inhibits elongation)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does geotropism affect the shoots and roots of a plant?

A

Shoots are negatively geotropic.

Roots are positively geotropic.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What effect does gravity have on auxin concentration?

A

Auxin moves in the direction of the force of gravity, causing shoots to grow up and roots to grow down.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How are roots hydrotropic?

A

Roots are positively hydrotropic (they grow towards higher water concentration).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is thigmotropism?

A

Growth response of shoots to physical contact e.g: vines.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What two scientists pioneered the work done to understand the role of plant hormones in tropisms?

A

Darwin and Boysen-Jensen

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What experiments can be done to show how auxin acts in phototropism?

A

Cover tip of shoot => plant does not grow toward light.
Insert sheet of plastic into half of the stem. If on the light half, phototropism is observed, if on the dark half, phototropism is not observed.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Why is our knowledge of plant hormones limited?

A

Hormones are in very low concentrations in plants.
Plant hormones act antagonistically.
Plant hormones can have different effects in different species/different tissues in the same plant.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is leaf abscission?

A

The dropping of leaves in deciduous trees.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Why does leaf abscission occur? (5)

A

The energy required to maintain leaves is more than is gained from photosynthesis in the winter.
Reduces water loss as transpiration stops.
Avoids frost damage.
Avoids fungal infection.
The fallen leaves add to the nutrient cycle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What plant hormones promote abscission?

A

Ethene and ABA (abscisic acid)

21
Q

What plant hormones inhibit abscission?

A

Auxin

22
Q

Where are auxins made in plants?

A

At the apex of (young) stems

23
Q

Where is ethene made in plants and what does it promote?

A

Ethene is made in ageing plant tissues and promotes senescence. (cell ageing)

24
Q

When is ABA created in plants?

A

In response to water/temperature stress.

25
Q

What hormones control stomatal closure?

A

ABA promotes stomatal closure and Auxin promotes stomatal opening.

26
Q

Why would stomata close and in what conditions?

A

Stomata close to prevent water loss.

Darkness, drought, cold or infection.

27
Q

Why would stomata open and in what conditions?

A

Stomata open to allow gas exchange and cooling.

high light intensity, high CO2 concentration, warmth.

28
Q

What happens to guard cells in order to open the stomata?

A

Guard cells become turgid.

29
Q

What plant hormones control seed germination?

A

ABA inhibits germination.

GA promotes germination.

30
Q

How does GA (gibberellic acid) promote germination?

A

GA activates transcription factors causing the transcription and translation of the enzyme amylase.
Amylase then digests the starch in the food stores of the seed, allowing cell growth and division.

31
Q

What effect does gibberellin (GA) (gibberellic acid) have in plants?

A

Gibberellin promotes seed germination.
Gibberellin produces tall, spindly plants by increasing elongation between nodes.
Gibberellin promotes the growth of lateral buds.

32
Q

How are dwarf varieties of crops created?

A

Crops such as rice and wheat are modified to lack one or more of the enzymes required to produce GA.

33
Q

Why are dwarf varieties of crops beneficial?

A

Dwarf varieties have a higher yield and are less likely to be knocked over by wind.

34
Q

What is the apical meristem?

A

The merismatic tissue on the tips of all shoots and roots.

35
Q

What is the lateral bud meristem?

A

Merismatic tissue in buds that can give rise to side shoots.

36
Q

What is the lateral meristem?

A

Cylinder of merismatic tissue near the outside of the stem and roots that gets wider with growth. (cambium)

37
Q

What is the coleoptile?

A

The first emerging shoot from the seed.

38
Q

What is apical dominance?

A

The inhibition of the growth of lateral buds by the presence of an active apical meristem (terminal bud).

39
Q

What is the terminal bud?

A

The apex of the plant that was once the coleoptile.

40
Q

What is produced at the apex that inhibits lateral budding?

A

Auxins.

41
Q

What happens if you cut the terminal bud off of a plant?

A

The plant will show more lateral budding.

42
Q

What do auxins NOT cause?

A

Cell division.

43
Q

How do auxins cause cell elongation?

how do they activate expansins

A

Auxin binds to the plasma membrane of the cell, causing ATPase enzymes to actively transport H+ ions into the cell wall.
This lowers the pH of the cell wall activating expansins (enzymes).

44
Q

How do expansins cause cell elongation?

A

Expansins break H-bonds in the microfibrils formed between cellulose molecules, loosening the cell wall.
This allows the cell to elongate as it takes more water into its vacuole.

45
Q

What role do phototropin proteins play in phototropism?

A

Phototropin proteins are actively phosphorylated by blue light on the sunny side of the plant.
This results in the redistribution of auxin to the dark side of the apex.

46
Q

How is ethene used commercially?

A

Ethene is used to ripen climactic fruit (fruit that ripen after being picked). Part of this process is the ethene increases the rate of respiration.

47
Q

What plant hormones are used as weed killers?

A

Synthetic dicot auxins.

48
Q

How do hormonal weed killers work?

A

Weeds are mainly dicotyledonous while crops are mainly monocotyledonous.
The synthetic auxins affect the metabolism of the weeds, causing an unsustainable growth rate.

49
Q

What hormone is used for rooting powder and what is it used for?

A

Auxins are used as they stimulate the production of roots, making it much easier to successfully propagate cuttings.

BIO (33 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions