5.4 Plant Responses To Abiotic Stress Flashcards Preview

A Level Biology > 5.4 Plant Responses To Abiotic Stress > Flashcards

Flashcards in 5.4 Plant Responses To Abiotic Stress Deck (28)
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1
Q

Trees loose their leaves in winter due to seasonal changes affecting what?

A

The amount of photosynthesis possible

2
Q

Trees loose their leaves at the point when the amount of glucose for respiration in the leaves is greater than what?

A

The amount of glucose photosynthesis can produce

3
Q

(Antifreeze) if cells freeze what happens to their membranes?

A

They are disrupted and they die

4
Q

(Antifreeze) the cytoplasm of plant cells and vacuoles contain what and what do they do?

A

Solutes

Lowering freezing points

5
Q

(Antifreeze) some plants produce what which act as antifreeze?

A

Sugars or amino acids

6
Q

(Antifreeze) these sugars and amino acids prevent the cytoplasm from freezing or protect what?

A

Cells from damage if they do freeze

7
Q

(Antifreeze) most plants only produce antifreeze when?

A

In winter

8
Q

(Antifreeze) different genes are suppressed and activated in response to what?

A

Temperature and day length preparing plants for frosty conditions

9
Q

(Stomatal control) plants can respond to stress by doing what to their stomata?

A

Open them allowing them to evaporate cooling the plant

Closing them to conserve water

10
Q

(Stomatal control) is controlled by which hormone?

A

ABA

11
Q

(Stomatal control) roots use ABA to warn of what?

A

Water stressors

12
Q

(Stomatal control) 1. There is a decrease in what?

A

Water

13
Q

(Stomatal control) 2. The roots produce what?

A

ABA

14
Q

(Stomatal control) 3. ABA is transported where?

A

To leaves

15
Q

(Stomatal control) 4. ABA binds to what in the leaves?

A

Receptors on guard cells

16
Q

(Stomatal control) 5. Binding activates changing in the what of guard cells?

A

Ionic concentration

17
Q

(Stomatal control) 6. Changes in the ionic concentration have what effect?

A

Reduce water potential and turgid of cells

So guard cells close the stomata

18
Q

(Abscission) what is abscission triggered by?

A

The lengthening of the dark period

19
Q

(Abscission) 1. Levels of what fall?

A

Light

20
Q

(Abscission) 2. Concentration of what falls?

A

Auxins

21
Q

(Abscission) 3. Leaves respond by producing what?

A

Ethene

22
Q

(Abscission)4. Ethene initiates gene switching where?

A

In the abscission zone - 2 layers of cells sensitive to ethene

23
Q

(Abscission) 4. Causes production of what?

A

New enzymes digesting and weakening cell walls in the separation layer

24
Q

(Abscission) 5. What is sealed off?

A

Vascular bundles a carrying materials into and out of the leaf

25
Q

(Abscission) 6. Fatty material is deposited where?

A

Cells on the stem side of the separation layer

26
Q

(Abscission) 7. The layer forms what?

A

A protective scar preventing pathogen entry when the leaf falls

27
Q

(Abscission) 8. Cells in the separation zone retain what?

A

Water causing them to swell putting more strain in the outer layer

28
Q

(Abscission) 9. Low temperatures and wind do what?

A

finish the process strain is too much and leaf separates

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