Physiox 9.0 exercise 1 - cell transport mechanisms and permeability

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1

Describe two variables that affect the rate of diffusion?

size of material and concentration of gradient.

2

Why do you think the Urea was not able to diffuse through the 20MWCO membrane?

because urea was too big to pass through the 20 MWCO membrane.

3

Describe the result of the attempt to diffuse glucose and albumin through the 200 MWCO membrane?

the glucose diffused through the 200MWCO membrane, while there was no diffusion of albumin.

4

Put the following in order from the smallest to largest molecular weight: glucose, sodium chloride, albumin, urea.

sodium chloride, urea, glucose, albumin.

5

Explain one way in which facilitated diffusion is the same as simple diffusion and one way in which it differs.

both are passive diffusion that are from high concentration gradient to a low concentration gradient. facilitated differs from simple because it requires a carrier protein to diffuse.

6

The larger value obtained when more glucose carriers were present corresponds to an increase in the rate of glucose transport. Explain why the rate increased.

the rate increased because there is more room and surface area increases relative to glucose.

7

Explain the effects that increasing the NaCl concentration had on osmotic pressure and why it has this effect.

Increasing the NaCl will increase the osmotic pressure. because water needs to diffuse to the higher concentration gradient until equilibrium is reached.

8

Describe one way in which Osmosis is similar to simple diffusion and one way in which it is different.

both are passive transports of high concentration gradient to low concentration gradient. Osmosis differs because it is the diffusion of water from a high to a low concentration gradient through a selective permeable membrane.

9

the conditions were 9 mM albumin in the left beaker and 10 mM glucose in the right beaker with the 200 MWCO membrane in place. Explain the results.

glucose diffuses from right beaker to the left beaker until equilibrium is reached. albumin can't diffuse through the membrane and osmotic pressure of 153mmHg results.

10

which solute did not appear in the filtrate using any of the membranes? explain why.

activated charcoal.

11

why did increasing the pressure increased the filtration rate but not the concentration of solutes?

because the pressure allows for more movement through the membrane but equilibrium was not reached.

12

describe the significance of using 9mM sodium chloride inside the cell and 6 mM potassium chloride outside the cell, instead of other concentration ratio.

because the Na/K pump allows for 3:2 ratio.

13

Explain why there was no sodium transport even though ATP was present.

in order for Na/K pump to function both ions need to be present even if ATP is present. since only Na was present it would use a passive diffusion down the concentration gradient.

14

Explain why the addition of glucose carriers had no effect on sodium or potassium transport.

because glucose concentration does not affect the Na/K concentration. it only has affect on glucose itself.

15

do you think glucose is being actively transported or transported by facilitated diffusion in this experiment? explain you answer.

it is being transported by facilitated diffusion. since glucose is a lipid insoluble and too large to pass through the membrane it requires a carrier but not ATP.