Osmosis

?
What is osmosis?
The diffusion of water molecules across a partially permeable membrane from an area of high water potential to a area of low water potential
1 of 15
Wat is the movement known as?
The net movement
2 of 15
What is water potential?
The potential (likelihood) of water molecules to diffuse out of or into a solution
3 of 15
What has the highest water potential?
Pure water
4 of 15
What does isotonic mean?
When two solutions have the same water potential
5 of 15
What factors affect diffusion?
Water potential gradient?, Thickness of exchange surface, Surface area of exchange surface
6 of 15
What is the Water potential gradient?
Higher the water potential the faster the rate of osmosis
7 of 15
What happens to the rate over time?
It decreases as the difference decreases on either side
8 of 15
Describe the process of making serial dilutions?
Start with an initial sucrose solution (e.g 2 M) and add 10 cm3 to the first test tube of five, and add 5cm3 of distilled water to the rest. Use a pipette to dra 5cm3 of the sucrose solution from the first test tube and add it to the distilled water
9 of 15
Cont.
in the second and mix. It is half as concentrated as the first (1M) Repeat three more times to get solutions of ).5M, 0.25M and 0.125M
10 of 15
How can you make serial dilutions by finding the scale factor?
Start with solution of known concentration, e.g 1M. Divide this concentration by the one ou want to make, e.g 0.4 M so 1/0.4 = 2.5, which means the solution is 2.5 times weaker, so you use 2.5 less of it, so take thet off the amount you want, and
11 of 15
Cont.
top up with water
12 of 15
How do you find the water potential of potato cells?
Cut potatoes into identically sized chips of 1 cm diameter, pat dry and weigh. Place a chip in each different concentration of sucrose solution for 20 minutes, then remove pat dry and weigh again. Calculate the percentage change in mass and and creat
13 of 15
Cont
a calibration curve showing % change in mass against sucrose concentration.
14 of 15
What should happen in this experiment?
Those in a solution with high water potential will gain water and therefore mass. They will lose water and therefore mass in solutions of low water potential
15 of 15

Other cards in this set

Card 2

Front

Wat is the movement known as?

Back

The net movement

Card 3

Front

What is water potential?

Back

Preview of the front of card 3

Card 4

Front

What has the highest water potential?

Back

Preview of the front of card 4

Card 5

Front

What does isotonic mean?

Back

Preview of the front of card 5
View more cards

Comments

No comments have yet been made

Similar Biology resources:

Osmosis
See all Biology resources »See all Cellular processes resources »