Transport across membranes

Question 1

What is active transport?

Answer 1

movement of molecules from an area of low concentration to an area of high concentration, against the concentration gradient using ATP

Question 2

How can we investigate how water potential affects the rate of osmosis?

Answer 2

placing potato chips in sucrose or salt solutions of different concentrations - note MASS CHANGE

Question 3

If the potato doesn’t change in mass, then what can we conclude?

Answer 3

the water potential of the solution is the same as the potato

Question 4

What is osmosis?

Answer 4

net movement of free water molecules from an area of high water potential to an area of low water potential, down a water potential gradient across a partially permeable membrane

Question 5

What happens to a plant cell if water moves in via osmosis?

Answer 5

cell becomes turgid - cell membrane very close to cell wall, cytoplasm looks full

Question 6

What happens to an animal cell if water moves in via osmosis?

Answer 6

cell becomes lysed (burst) - no cell wall to prevent bursting

Question 7

What happens to a plant cell if water moves out via osmosis?

Answer 7

plasmolysis occurs - cell membrane pulls away from cell wall, cell wall is fully permeable so some water can be found between cell wall and membrane

Question 8

What happens to an animal cell if water moves out via osmosis?

Answer 8

cell becomes shrivelled