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Flashcards in 15 - Plant signalling Deck (50)
1

Signal Transduction causes two responses, what are they?

 

  1. Pi'n cascade
  2. 2nd messanger

2

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

 

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

3

list some of the potential signals

 

  • light
  • gravity
  • chemical
  • hormones
  • touch

4

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

 

No

5

In plants what is the typical 2nd messanger?

 

Ca2+

6

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

 

auxin

7

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

 

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

8

Describe whats going on with phtotropism

growth towards the light "light turning"

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

9

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

 

expansins

10

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

 

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

11

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

 

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

12

What is the root of the workd gravitropism

 

"gravity-turning"

13

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

 

root cap

14

What is the statolith hypothesis?

 

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

15

How do the amyloplasts support the statolith hypothesis

 

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

16

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

 

starch

17

what is the hormone responsible for phototropism and gravitropism

 

auxin

18

What is up with 2-4-D

 

herbicide - uncontrolled growth of dicots

doesnt kill lawns

kills broad leaves - monocots

19

What is the root term of cytokinins

 

cell division

20

what do cytokinins do?

 

causes cell division

21

What is the role of cytokinins

 

  • lateral bud growth
  • delay in aging

22

What is the role of the hormone gibberellins?

 

  • growth stimulation
  • stem growth and elogation
  • flower stimulation
  • seed germination

23

__________ stimulates growth and ___________ inhibits it

 

Gibberellins

Abscisic acid or ABA

24

what does gibberellins do to starch?

 

converts to sugar

25

What does ABA do ?

 

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

26

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

 

Senescence

27

What is the hormone most strongly associated with senscence?

 

ethylene

28

What are the three aspects of senescence that ethylene contibutes to

 

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

29

define abscission

 

detachment of leaves

30

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

 

ethylene

31

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

 

ethylene and cytokinins

32

___________ can define the long axis of the body

 

auxin

33

__________ promote cell growth

 

gibberellins

34

__________  promote cell division

 

cytokinins

35

___________ slows or prevents growth

 

ABA

36

_______________ signals senescence

 

ethylene

37

Describe how stomata close in response to ABA

 

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

What is tropism

 

directed response to a stimulus

39

name the different types of tropisms

 

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

40

What does nastic movement mean

 

no directional movement

41

What kind of movement do guard cells do?

nastic movements - turgor

42

what is seismonasty movement?

 

movement in response to physical touch

ie- closing up if a bug comes to eat them

43

what is nyctinasity movement?

 

response to light

44

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

 

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

45


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

Thigmomorphogenesis

46


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

Abscisic acid

47


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
 

Auxin

48

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

Cause flowering in plants

49


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
 

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

50