The driving force for diffusion is |
the kinetic energy of the molecules in motion. |
In diffusion, molecules move |
from high concentration to low concentration. |
Which of the following dialysis membranes has the largest pore size? |
200 MWCO |
Avogadro’s number is a constant for the number of |
molecules. |
The reason sodium chloride didn’t diffuse left to right is that |
the membrane pore size was too small. |
Glucose is a six-carbon sugar. Albumin is a protein with 607 amino acids. The average molecular weight of a single amino acid is 135 g/mole. There is no reason to run these solutes at the 20 MWCO because |
glucose and albumin are both too large to pass. |
The rate of diffusion for urea |
is slower than that for sodium because urea is a larger molecule. |
The effect of increasing the concentration of sodium chloride from 9 mM to 18 mM in the left beaker was to |
increase the rate of diffusion. |
Describe the difference between the rate of diffusion seen for sodium and urea. |
Urea diffused more slowly because it is larger than sodium. |
Which of the following solutes did not pass through any of the membranes? |
albumin |
When diffusion stops, we say the solution has reached |
equilibrium. |
Molecules need a carrier protein to help them move across a membrane because |
they are lipid insoluble or they are too large. |
Which of the following is true of facilitated diffusion? |
Movement is passive and down a concentration gradient. |
Which of the following would not affect the rate of facilitated diffusion? |
the amount of intracellular ATP |
What happened to the glucose transport rate when the glucose concentration was increased from 2 mM to 8 mM? |
The glucose transport rate increased. |
Describe the conditions that resulted in the fastest rate of glucose transport. |
700 glucose carrier proteins and 8 mM glucose |
Why do you think equilibrium wasn’t reached? |
The membrane proteins were saturated. |
For facilitated diffusion, increasing the concentration of glucose on one side of the membrane is the same as |
making the concentration gradient steeper |
When all of the membrane carriers are engaged, or busy, we say they are |
saturated |
Na+ Cl- had no effect on glucose transport because |
sodium is not required for glucose transport in the simulation. |
Which of the following is true of osmosis? |
It is a type of diffusion |
Which of the following occurs when a hypertonic solution is added to cells? |
The cells shrink. |
The variable that affects osmotic pressure is |
the concentration of nondiffusing solutes. |
The net movement of water would be into the cell in a |
hypotonic solution. |
Why do you think there is no pressure change? |
Sodium is able to diffuse through the pores. |
Why do you think there was no pressure change? |
There is no net movement of water because the solute concentrations are the same. |
If you double the concentration of a nondiffusible solute that is on one side of a membrane, the osmotic pressure will |
double |
Which membrane did not allow Na+ Cl- to pass through? |
20 MWCO |
When a solute is able to diffuse through a membrane |
equilibrium is reached. |
water diffuses |
towards solutes |
The movement of sodium and potassium maintained by the Na+ -K+ pump |
requires energy and is against a concentration gradient |
The sodium-potassium pump is classified as a(n) |
antiporter. |
The sodium-potassium pump moves _____ sodium ions and _____ potassium ions simultaneously. |
3, 2 |
Solutes that require active transport for movement might be too large to pass or might be |
lipid insoluble. |
Why did the sodium transport stop before the transport was completed? |
The ATP was depleted. |
Why was the equilibrium for the solutes reached earlier? |
There were more pumps for transport. |
What happened when you increased the amount of ATP dispensed with the same concentration of sodium and |
More ions were transported. |
At what concentration of ATP were the sodium and potassium maximally transported? |
3 mM ATP |
What was the effect of adding more Na+ -K+ pumps to the simulated cell? |
Transport of the ions was faster. |
Describe the effect of adding glucose carriers to the sodium and potassium transport |
There was no change in the transport rate because glucose is transported independently. |
A&P Physio Ex
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