5.4 Plant Responses To Abiotic Stress

Question 1

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

Answer 1

The amount of photosynthesis possible

Question 2

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

Answer 2

The amount of glucose photosynthesis can produce

Question 3

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

Answer 3

They are disrupted and they die

Question 4

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

Answer 4

Solutes

Lowering freezing points

Question 5

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

Answer 5

Sugars or amino acids

Question 6

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

Answer 6

Cells from damage if they do freeze

Question 7

(Antifreeze) most plants only produce antifreeze when?

Answer 7

In winter

Question 8

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

Answer 8

Temperature and day length preparing plants for frosty conditions

Question 9

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

Answer 9

Open them allowing them to evaporate cooling the plant

Closing them to conserve water

Question 10

(Stomatal control) is controlled by which hormone?

Answer 10

ABA

Question 11

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

Answer 11

Water stressors

Question 12

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

Answer 12

Water

Question 13

(Stomatal control) 2. The roots produce what?

Answer 13

ABA

Question 14

(Stomatal control) 3. ABA is transported where?

Answer 14

To leaves

Question 15

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

Answer 15

Receptors on guard cells

Question 16

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

Answer 16

Ionic concentration

Question 17

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

Answer 17

Reduce water potential and turgid of cells

So guard cells close the stomata

Question 18

(Abscission) what is abscission triggered by?

Answer 18

The lengthening of the dark period

Question 19

(Abscission) 1. Levels of what fall?

Answer 19

Light

Question 20

(Abscission) 2. Concentration of what falls?

Answer 20

Auxins

Question 21

(Abscission) 3. Leaves respond by producing what?

Answer 21

Ethene

Question 22

(Abscission)4. Ethene initiates gene switching where?

Answer 22

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

Question 23

(Abscission) 4. Causes production of what?

Answer 23

New enzymes digesting and weakening cell walls in the separation layer

Question 24

(Abscission) 5. What is sealed off?

Answer 24

Vascular bundles a carrying materials into and out of the leaf

Question 25

(Abscission) 6. Fatty material is deposited where?

Answer 25

Cells on the stem side of the separation layer

Question 26

(Abscission) 7. The layer forms what?

Answer 26

A protective scar preventing pathogen entry when the leaf falls

Question 27

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

Answer 27

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

Question 28

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

Answer 28

finish the process strain is too much and leaf separates