Brainscape's Knowledge GenomeTM

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


See full index

the green planet 2 > plant growth and development > Flashcards

plant growth and development Flashcards

1
Q

what is an example of slow plant movement

A

bean wrapping round a pole.

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

what is an example of rapid plant movement?

how does it work?

A

VENUS FLY TRAP

  1. at the hinge, cells go turgid.
  2. in response to stimuli these cells lose turgor.
  3. this combined with mechanisation turns the hinge into a spring.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

how do Venus fly traps save energy?

A

shutting mouth is very energetically expensive so the following can be done to make sure jaw opens a minimal amount of times.

  1. 3 sensitive hairs on inside of jaws to ensure only something right inside will set it off.
  2. have to touch a hair twice for it to close.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

examples of directional stimuli

A
  1. light
  2. gravity
  3. touch
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what is needed for gravitropism?

A
  1. perception (statocytes)
  2. signal transduction (auxin redistribution)
  3. mechanical response (bending, differential cell expansion)
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

which way do shoots and roots grow?

A

roots grow towards gravity.

shoots grow away from gravity.

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

where does gravitropism perception occur?

A

root caps and shoot tip endodermis

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

how are trees able to show gravitropism

A

when a woody stem is stimulated, tension wood pulls and contracts to pull the tree upwards.

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

what happened when the root tip was surgically removed

A

the root still grew however it did not curl towards gravity as its perception cells were removed.

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

statocytes

A

specialised cells in root cap.

they contain statoliths (starch filled bodies). these statoliths sediment with gravity. this directs growth of the root.

abolition of these statocytes - loss of gravitropism

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

how does gravity inhibit growth in roots?

A

auxin is redistributed and this inhibits growth.

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

how dos gravity promote growth in shoots?

A

on underside of curve, auxin accumulates to promote growth and push the root upwards.

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

characteristics of auxin transport

A
  1. long distance (shoot to root) in phloem sap
  2. cell to cell - active transport NOT diffusion
  3. highly polar - in shoots down not up.
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

PIN proteins

A

pump auxin out of cells as it is a weak acid and can’t get through the polar membrane.

gradually pumps auxin from cell to cell down to the bottom of the root.

located on plasma membrane

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

PIN 3

A

this protein re-localises in response to gravity - means that auxin accumulates on one side.

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

lazy mutant

A

maize mutant that didn’t show gravitropism because lazy proteins moves with amyloplasts.

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

short day plants

A

flower when day length is shorter than a defined period

(flower when days are short)

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

long day plants

A

flower when day length is longer than a critical period.

(flower when days are long)

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

phytochrome

A

pigment in plants which can detect light.

in sunlight it is in Pfr form.

in night it is in Pr form.

20
Q

external coincidence model

A

proposed that:

  1. there is an internal rhythm with approx 24 hour period in the amount of a substance controlling flowering.
  2. this substance is light sensitive at a particular phase in the rhythm.
21
Q

why do plants need a circadian rhythm?

A

allows plants to predict dawn and get ready for it (bring up its leaves and switch on photosynthesis)

22
Q

the photoperiod pathway

A
  1. perception of light
  2. things that perceive light (photoreceptors) keep the clock accurate
  3. some genes are involved in flowering time (LHY, CCA1, TOC1 etc)
  4. output - substance which is important for flowering or leaf movement.
23
Q

constans gene

A

output of photoperiod pathway

  • inactivate this - affects the flowering time.
  • promotes flowering in long days
  • expression shows circadian rhythm
  • lots of CO protein on a long day
24
Q

florigen

A

signal that moves from leaves to shoot apical meristem after induction by day length.

expressed in leaves in long day plants

25
Q

what properties should a gene for florin have?

A
  1. mutants should not respond to day length
  2. should be expressed in leaves in inductive conditions
  3. should promote flowering across grafts
  4. should make a product that can move from leaves to the shoot apical meristem where flowering occurs.
  5. should be universal.
26
Q

spores are produced by…

A

diploid cells

27
Q

gametes are produced by…

A

haploid cells

28
Q

double fertilisation

A

egg cell is fertilised at the same time as a central cell. central cell is fertilized to make endosperm which provides nutrients to the embryo.

28
Q

alternation of generations

A

as well as having a multicellular diploid generation, plants also have a multicellular haploid generation.

29
Q

important steps in embryo development

A
  1. Morphogenesis - establishing the basic pattern
  2. Maturation - fuel storage and proteins that enable seed to survive desiccation
  3. degreasing - chlorophyll broken down and embryo turns yellow.
  4. desiccation - removal of moisture
  5. dormancy
30
Q

seed dormancy

A

seeds are said to be dormant when fail to germinate even with the idea conditions.

31
Q

how is dormancy controlled?

A
  1. ABA accumulates and promotes dormancy.
  2. gibberellins promote germination
32
Q

what is the maize viviparous1 mutant?

A

germinates prematurely on the cob as it doesn’t undergo dormancy.

this mutant doesn’t respond to ABA.

33
Q

abi3 mutant.

A
  • ABA insensitive.
  • abi3 is thought to be involved in signalling - stops perception of ABA which stops dormancy.
  • plants with abi3 mutant don’t survive storage.
34
Q

gibberellin

A
  • promote germination.
  • involved in height growth - plants that can’t make gibberellins tend to be dwarfed.
  • gibberellins inhibits effects of ABA.
35
Q

how does gibberellin work?

A

gibberellin signal is produced to promote aleurone to begin breakdown of endosperm after germination.

36
Q

what is a commercial application of GA?

A

to make malt whiskey.

37
Q

environmental controls on seed dormancy.

A

time - tough seed coat may gradually be broken down.

light - flash of light when tree falls down and suddenly there is the chance to grow.

nitrates - may indicate a nutrient rich soil.

internal cellular controls - after ripening - GA and ABA.

38
Q

what effect does red light and far red light have on germination of seeds.

A

red light - promotes germination

far red light - inhibits germination.

39
Q

how are light and GA levels connected?

A
  1. red light converts phytochrome into its active form.
  2. various signalling/transcription factors eventually connect phytochrome with an enzyme that is involved in gibberellin synthesis.
40
Q

what breaks seed dormancy?

A
  1. fire - resistance to fire provides an advantage to the plant as it eliminates its competitors.
  2. parasitic weeds
41
Q

karrikin

A

karrikin in smoke promotes germination in seeds

42
Q

parasitic weeds (Striga)

A
  1. grows towards host root, attaches via adhesive hairs.
  2. penetrates root via a haustorium which secretes enzymes that digest host cell walls.
  3. transpires rapidly - pulling water and nutrients from the host.
43
Q

strigolactones

A

signals produced by plants that promote the germination of parasitic weeds (ONLY!!)

44
Q

pathway of how phosphorus concentration impacts plants.

A
  1. in low phosphorous plant is starved and so makes more strigolactones.
  2. this promotes less shoot branching but more root branching
  3. more strigolactones also promotes more mycorrhizal colonisation
  4. more strigolactones also advertises their presence to weeds however…

the green planet 2 (10 decks)

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