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):
1

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

The amount of photosynthesis possible

2

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

The amount of glucose photosynthesis can produce

3

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

They are disrupted and they die

4

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

Solutes
Lowering freezing points

5

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

Sugars or amino acids

6

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

Cells from damage if they do freeze

7

(Antifreeze) most plants only produce antifreeze when?

In winter

8

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

Temperature and day length preparing plants for frosty conditions

9

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

Open them allowing them to evaporate cooling the plant
Closing them to conserve water

10

(Stomatal control) is controlled by which hormone?

ABA

11

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

Water stressors

12

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

Water

13

(Stomatal control) 2. The roots produce what?

ABA

14

(Stomatal control) 3. ABA is transported where?

To leaves

15

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

Receptors on guard cells

16

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

Ionic concentration

17

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

Reduce water potential and turgid of cells
So guard cells close the stomata

18

(Abscission) what is abscission triggered by?

The lengthening of the dark period

19

(Abscission) 1. Levels of what fall?

Light

20

(Abscission) 2. Concentration of what falls?

Auxins

21

(Abscission) 3. Leaves respond by producing what?

Ethene

22

(Abscission)4. Ethene initiates gene switching where?

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

23

(Abscission) 4. Causes production of what?

New enzymes digesting and weakening cell walls in the separation layer

24

(Abscission) 5. What is sealed off?

Vascular bundles a carrying materials into and out of the leaf

25

(Abscission) 6. Fatty material is deposited where?

Cells on the stem side of the separation layer

26

(Abscission) 7. The layer forms what?

A protective scar preventing pathogen entry when the leaf falls

27

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

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

28

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

finish the process strain is too much and leaf separates

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