transport across cell membrane

Question 1

describe the way in which the appearance of a plant cell wall would differ from a cell membrane when viewed with an electron microscope

Answer 1

• thicker

- the plant cell wall contains fibrils

Question 2

describe the part played by cell surface membrane in regulating the movement of substances in and out of cells

Answer 2

Non - polar/ lipid soluble molecules move through phospholipid bilayer

small molecules move through phospholipid layer

water soluble substances move through protein channels

some protein channels are gated/ only allows the passage of some molecules

some carrier protiens are associated with active transport

Question 3

explain how amino acids molecules may be linked to form a polypeptide chain which is folded into a specific tertiary shape

Answer 3

1. condenstation reaction involving the removal of water
2. from amino and carboxyl group
3. forming a peptide bond
4. same amino acids in same sequence
5. bonds form betweeR- group hold the peptide in place

Question 4

Explain why glucagon only effects liver cells

Answer 4

1. glucagon has a specific shape
2. the receptor molecules have specific binding sites
3. that is only complementary to the structure of glucagon
4. so they fit together

Question 5

explain two ways in the diagram in which the structure of this cell ensures efficient absorption of glucose from the inside of the kidney

Answer 5

1. MICROVILI provides a large surface area for facillitated diffusion
2. removal of glucose out a cell maintain concentration gradient

Question 6

what is the molecular formula of lactose

Answer 6

C6 H12 O6 + C6H12O6 -(H2O)

Question 7

describe how the process shown in diagram enable the epithelial cells to absorb amino acids continuously

Answer 7

1. amino acids removed from cell into blood stream by active transport
2. ATP used for active transport
3. maintains a low concentration in cell so concentration gradient is always maintained between ileum and cell
4. entry by facilitated diffusion

Question 8

Describe how you would use the student’s results in the table above to find the
water potential of the potato tissue

Answer 8

1. Plot a graph with concentration on the x-axis and percentage change in
   mass on the y-axis;
2. Find concentration where curve crosses the x-axis / where percentage
   change is zero;
3. Use (another) resource to find water potential of sucrose concentration
   (where curve crosses x-axis).