Turgor pressure

Question 1

Whats the key difference between animal and plant cells?

Answer 1

Plant cells have a cell wall and a vacuole (to generate huge pressures)

Question 2

How is pressure generated in cell walls?

Answer 2

The cell wall restricts the expansion of the protoplast

Question 3

What is on example of a turgor driven movement?

Answer 3

Venus fly trap

Question 4

How is turgor pressure used in movement processes of plants? (5)

Answer 4

• gravitropism
• hydrotropism
• light stimulated responses
• reproduction
• pollen tube growth

Question 5

Why is turgor pressure so vital in the support of plants? (4)

Answer 5

• loss of turgor in non woody tissues causes wilting which limits photosynthesis
• can’t transport any sugars as the phloem doesn’t have any pressure
• leaves can’t intersect light as they have drooped
• damage to cells lead to non-functioning

Question 6

What role does turgor pressure play in the stomata?

Answer 6

• 2 guard cells shut when turgor pressure drops

Question 7

How is turgor pressure generated?

Answer 7

• water moves into cell by osmosis
• because solutes accumulate in the vacuole
• vacuole swells and the protoplast is pushed against cell wall

Question 8

Define turgor pressure

Answer 8

the force within the cell that pushes the plasma membrane against the cell wall.

Question 9

Define osmosis

Answer 9

diffusion of water down its own concentration gradient

Question 10

What is the effect of solutes on the cell wall?

Answer 10

solutes added decrease teh concentration of water, pure water outside cell wall will diffuse in

Question 11

What is the most pressured compartment in a plant cell?

Answer 11

The phloem

Question 12

Why is the structure of the membrane important in cells?

Answer 12

Its semi permeable to allow water to cross the wall by osmosis

Question 13

What is the difference between hypertonic and hypotonic solutions?

Answer 13

Hypertonic solutions have a higher concentration of solutes whereas hypotonic have a lower concentration

Question 14

What the effects of a hypotonic solution on turgor pressure in cells?

Answer 14

Cells gain water and protoplast is pushed against cell wall

Question 15

What the effects of a hypertonic solution on turgor pressure in cells?

Answer 15

a cell wall gives no advantages, cell looses water, volume shrinks, membrane pulls away from cell wall

Question 16

What are aquaporins?

Answer 16

membrane proteins forming water channels and are essentially the biochemical basis of osmosis

Question 17

What is the role of aquaporins?

Answer 17

they can open and close to regulate the membrane permeability by closing them

Question 18

What processes are balanced when the water pressure is 0?

Answer 18

• accumulation of solutes and lowering the concentration of water inside the cell

Question 19

What does the water potential need to be in order for a cell to take up water and generate turgor pressure?

Answer 19

lower water potential than its environment

Question 20

How do you make water potential more negative?

Answer 20

Lower the turgor pressure or increase teh osmotic pressure

Question 21

What is the difference between the primary and the secondary cell wall?

Answer 21

primary= growing
secondary= lignified remains of primary cell wall

Question 22

How do plants grow?

Answer 22

by individual cells expanding by taking up more water

must have lower water potential on outside

Question 23

What is the effect of turgor pressure on growth?

Answer 23

lower turgor = slower growth

higher turgor = faster growth

Question 24

What is the plant’s cell wall made of?

Answer 24

cellulose microfibrils

Question 25

What is the effect of temperature on cell walls?

Answer 25

lower temperature, less extensible cell walls

Question 26

What is the difference between expansin and extension in the cell wall?

Answer 26

extensin = reduces extension
expansin = allows extension

Question 27

Name some cell wall components

Answer 27

cellulose
hemicellulose
pectin
protein
lignin

Question 28

What is the effect of acid protons on the cell wall?

Answer 28

it will compete with the hydrogen bonding and will weaken teh hydrogen bonding, manipulating the ph of cell wall

Question 29

What is teh acid growth hypothesis?

Answer 29

acidified walls will grow faster and loosens wall

Question 30

Why does auxin stimulates growth?

Answer 30

• it stimulates the proton ATPase in the plasmalemma
• and it exudes protons into the cell wall
• and solidifies the cell wall by extension growth
• so increased cell extension by weakening hydrogen bonds between teh xylogucan and teh cellulose microfibrils

Question 31

How is growth related to cell walls?

Answer 31

increase in growth is due to increased loosening of cell wall

Question 32

What is the role of expansins?

Answer 32

loosen hydrogen bonds between xylogucan and cellulose

Question 33

How does the tightening of cell walls lead to an increase in extension? (5)

Answer 33

• longitudinal microfibril orientation
• increase cross links between polymers
• de esterifying teh pectic acids
• increases pectin cacium bridges
• increase in extension

Question 34

What is the secondary cell wall composed of and its role?

Answer 34

• cellulose and lignin

- mainly for support

Question 35

What is the difference in extensibility between secondary and primary cell wall?

Answer 35

primary are extensible whereas secondary are not

Question 36

What is the difference in lignin content between secondary and primary cell wall?

Answer 36

primary don’t have lignin whereas secondary do contain lignin

Question 37

How do you calculate water potential?

Answer 37

Turgor pressure - osmotic pressure

Question 38

Name 5 things that turgor pressure ahs a role in plants?

Answer 38

• stomata
• movement
• phloem
• growth
• suppoty