CELLS: Osmosis Flashcards

You may prefer our related Brainscape-certified flashcards:
1
Q

Osmosis.

A

Passage of water from a region where it has higher water potential to an area where it has a lower water potential through a selectively permeable membrane.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Water potential.

A

Likelihood of water molecules to diffuse out of or into a solution.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Isotonic.

A

Two solutions have same water potential.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Solute.

A

Any substance that is dissolved in a solvent.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What has the highest water potential?

A

Pure water.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Under standard conditions of temperature and pressure, what is the water potential or pure water?

A

0

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

The addition of a solute to pure water…

A

… will lower its water potential.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

The water potential of a solution (water + solute) must always be what?

A

Less than 0 - a negative value.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

The rate of osmosis depends on what factors?

A
  • Water potential gradient
  • Thickness of exchange surface
  • Surface area of the exchange surface
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

How does the water potential gradient affect the rate of osmosis?

A

The higher the water potential gradient, the faster the rate of osmosis.

As osmosis takes place, the difference in water potential on either side of membrane decreases, so the rate of osmosis levels off.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How does the thickness of exchange surface affect the rate of osmosis?

A

The thinner the exchange surface, the faster the rate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

How does the surface area of the exchange surface affect the rate of osmosis?

A

The larger the surface area, the faster the rate.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How would you make 5 serial dilutions?

A
  1. Add 10cm3 of 2 M sucrose solution to 1st test tube
  2. Add 5cm3 distilled water to other 4 test tubes
  3. Use a pipette to add 5cm3 of solution from first test tube to second test tube + mix
  4. Repeat taking 5cm3 from second test tube and adding to third.
  5. Results = 2M , 1M, 0.5M, 0.25M, 0.125M
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

How would you investigate the water potential of potato cells?

A
  1. Cut potatoes into identical sizes
  2. Divide into groups of 3 and measure mass of each group
  3. Place 1 group into each sucrose solution
  4. Leave for set period
  5. Remove and pat dry
  6. Weigh using mass balance
  7. Calculate % change in mass
  8. Use results to make calibratio curve, showing %change in mass vs sucrose concentration.
  9. Gain mass = higher water potential of solution than chips
  10. Where curve crosses x-axis = WP of sucrose is same as potato
How well did you know this?
1
Not at all
2
3
4
5
Perfectly