4. transport across cell membranes

Question 1

name four features of the cell membrane

Answer 1

proteins (channel, carrier, extrinsic)

cholesterol, stability

glycolipids, recognition

glycoproteins, recognition

Question 2

what type of molecules can pass through the cell membrane

Answer 2

small, soluble in lipids, uncharged

Question 3

describe the fluid-mosaic model

Answer 3

fluid, the bilayer is flexible, changing shape

Mosiac, proteins vary in shape and size and pattern

Question 4

what happens if an animal cell is in a solution of high water potential

Answer 4

water is of a higher ‘concentration’ outside the cell, water enters cell causing it to swell and burst

Question 5

what does it mean if a cell is in an isotonic solution

Answer 5

water potential inside = outside

Question 6

what does hyper-tonic mean

Answer 6

water potential;
outside cell < inside cell

Question 7

Osmosis

Answer 7

high water pot - low water pot

Question 8

Explain what happens to plant cells when they are in solutions of high and low water potential.

Answer 8

HIGH WATER POTENTIAL
- water enters cell
- cytoplasm pushing against cell wall
- Turgid

LOW WATER POTENTIAL
- water leaves cell
- cells shrinks
- plasmolysed