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Biology > 15 - Plant signalling > Flashcards

15 - Plant signalling Flashcards

1
Q

Signal Transduction causes two responses, what are they?

A
  1. Pi’n cascade
  2. 2nd messanger
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2
Q

In response to a signal being transduced into the plant, what are the potential next steps in signal transduction?

A
  • activate/deactivate genes
  • increase or decrease protein activity - translation
  • Increase or decrease Ion flow - channel or pump
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3
Q

list some of the potential signals

A
  • light
  • gravity
  • chemical
  • hormones
  • touch
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4
Q

Where the stimulus of a signal is elicited, is this also where the response will happen?

A

No

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5
Q

In plants what is the typical 2nd messanger?

A

Ca2+

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6
Q

Which hormone supports the growth in the main stem yet ensure lateral buts remain dormant?

A

auxin

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7
Q

What is the effect of a high concentration of auxin on a plant?

A

hight concentration will bring water, causing cells to elongate and growth - therefore bending

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8
Q

Describe whats going on with phtotropism

A

growth towards the light “light turning”

[] increases on darker side of plant causing elongation of cells

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9
Q

what is the protein that have been found that make cell walls extensibe by interfering with the ionic bonds b/t cellulose microfibrils - causing cell walls to loosen and new cellulose nmicrofibrils produced to extend the cells length

A

expansins

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10
Q

What are the two things that must happed for a plant to get larger?

A
  1. cell wall must expand - expansins
  2. increase in volument and turgor pressure - increase [K+] therefore increase H2O
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11
Q

Describe the steps to the acid-growth hypothesis for cell elongation

A

What activated proton pumps lower the pH outside the cell membrane in response to auxin, a series of events leads to

  • and intake of water
  • expansion of the cell wall

Result: expansion of cell wall

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12
Q

What is the root of the workd gravitropism

A

“gravity-turning”

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13
Q

Where are the cells found that are responsible for responding to gravity

A

root cap

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14
Q

What is the statolith hypothesis?

A

that dense starch-storing organelles called amyloplasts fxn as gravity receptors

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15
Q

How do the amyloplasts support the statolith hypothesis

A

gravity pulls the heavy amyloplasts to the bottom of the cells, activiating sensory protein that initates the gravitropic response

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16
Q

What are the amyloplasts filled with making them dense and therefore more heavy

A

starch

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17
Q

what is the hormone responsible for phototropism and gravitropism

A

auxin

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18
Q

What is up with 2-4-D

A

herbicide - uncontrolled growth of dicots

doesnt kill lawns

kills broad leaves - monocots

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19
Q

What is the root term of cytokinins

A

cell division

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20
Q

what do cytokinins do?

A

causes cell division

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21
Q

What is the role of cytokinins

A
  • lateral bud growth
  • delay in aging
22
Q

What is the role of the hormone gibberellins?

A
  • growth stimulation
  • stem growth and elogation
  • flower stimulation
  • seed germination
23
Q

__________ stimulates growth and ___________ inhibits it

A

Gibberellins

Abscisic acid or ABA

24
Q

what does gibberellins do to starch?

A

converts to sugar

25
Q

What does ABA do ?

A
  • Inhibits bud growth & seed germination
  • closes stomata when H2O stressed
26
Q

__________ is the regulation process of aging, decline, and eventual death of an entire organism or particular organs such as plant fruits and leaves

A

Senescence

27
Q

What is the hormone most strongly associated with senscence?

A

ethylene

28
Q

What are the three aspects of senescence that ethylene contibutes to

A
  1. fruit ripening
  2. fading of flowers
  3. abscission - detachment of leaves
29
Q

define abscission

A

detachment of leaves

30
Q

What do fruit growers manuipulate in order to control fruit ripening?

A

ethylene

31
Q

___________ and __________ are thought to have opposite effects on some of the processes involved in senscence

A

ethylene and cytokinins

32
Q

___________ can define the long axis of the body

A

auxin

33
Q

__________ promote cell growth

A

gibberellins

34
Q

__________ promote cell division

A

cytokinins

35
Q

___________ slows or prevents growth

A

ABA

36
Q

_______________ signals senescence

A

ethylene

37
Q

Describe how stomata close in response to ABA

A

ABA binds to receptors on guard cells

  • pumping by H+ ATPases stops. Outward-directioed Cl- exits along electrochemical gradient
  • change in Mb potential opens outward directed K+ channels. K+ exits along electrochemical gradient
  • H2O follows by osmosis
  • Cell shrinks
38
Q

What is tropism

A

directed response to a stimulus

39
Q

name the different types of tropisms

A
  • thigmotropism - bending to touch - ie tendrils
  • thigmomorphogensesis - stems grow shorter or thicker - ie alpine trees due to wind
  • Gravitropism
  • phototropism
  • hydrotropism
40
Q

What does nastic movement mean

A

no directional movement

41
Q

What kind of movement do guard cells do?

A

nastic movements - turgor

42
Q

what is seismonasty movement?

A

movement in response to physical touch

ie- closing up if a bug comes to eat them

43
Q

what is nyctinasity movement?

A

response to light

44
Q

All of the following statements about plant hormones are correct EXCEPT for:

Select one:

a. They can trigger a phosphorylation cascade
b. They can exist in a gaseous form
c. They trigger a response by binding to a receptor.
d. They exert their effects only in the same cells that produce them.
e. They can increase the amount of protein in a cell

A

They exert their effects only in the same cells that produce them.

45
Q

The plant response to wind is called
Select one:
A. Seismonasty
B. Phototropism
C. Nyctinasty
D. Apical dominance
E. Thigmomorphogenesis

A

Thigmomorphogenesis

46
Q

The hormone that helps plants respond to drought is
Select one:
A. Gibberellin
B. Cytokinin
C. Ethylene
D. Abscisic acid
E. Auxin

A

Abscisic acid

47
Q

If you pinched your plant back to make it bushier you would be pinching off
Select one:
A. Cytokinin
B. Abscisic acid
C. Ethylene
D. Gibberellin
E. Auxin

A

Auxin

48
Q

The gibberellins

Select one:
A. Are gases at room termperature
B. Are produced only by fungi
C. Are responsible for phototropism and gravitropism
D. Cause flowering in plants
E. Inhibit the synthesis of digestive enzymes by barley seeds

A

Cause flowering in plants

49
Q

Fruit bowls and hanging baskets often have open wires. What is the advantage of these open spaces?
Select one:
A. Prevents gibberellins from causing the formation of flowers on the fruit
B. Allows oxygen in the air to stimulate the production of abscisic acid to hasten the ripening of fruit
C. Allows sunlight to penetrate through the openings to stimulate fruit ripening
D. Allows the evaporation of ethylene, thus slowing ripening of the fruit
E. Allows carbon dioxide in the air to stimulate cytokinin production to stimulate fruit ripening

A

Allows the evaporation of ethylene, thus slowing ripening of the fruit

50
Q
A

Biology (18 decks)

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