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5 years ago
ACTIVITY 1:  Simulating Dialysis (Simple Diffusion)
1.   The molecular weight of urea is approximately 60.  Which of the membranes can it pass through?
a.   50 MWCO membrane
b.   100 MWCO membrane            
c.   200 MWCO membrane
d.   Both the 100 and 200 MWCO membranes    D. Both  the 100 and 200 MWCO membranes
2.   True or False:  A solution containing glucose will diffuse faster through a 200 MWCO membrane if it is heated.   True
3.   The molecular weight of carbon C is 12; the molecular weight of hydrogen (H) is 1; the molecular weight of oxygen (O) is 16.  The chemical formula of glucose is:  C6H12O6 .   Using some simple multiplication and addition, determine the molecular weight of one molecule of glucose.          (6x12)+(12x1)+(6x16)=180 g/mol
4.   Describe two variables that affect the rate of diffusion.   If temperature  and the size of the molecule are factor in two elements will have an effect in diffusion 
5.   Why do you think that the urea was not able to diffuse through the 20 MWCO membrane?   It did not diffuse because of saturation.
6.   Describe the results of the attempts to diffuse glucose and albumin through the 200 MWCO membrane.   Albumin did not diffuse.
7.   Put the following in order from smallest to largest molecular weight:  glucose, sodium chloride, albumin, and urea.     Sodium Chloride, Urea, Glucose, Albumin
ACTIVITY 2:  Simulated Facilitated Diffusion
8.   True or False:  The facilitated diffusion of glucose requires energy from ATP.      False
9.   Which of the following might cause the facilitated diffusion of glucose from one solution to another to occur faster?
a.   Add Na+Cl- to the beaker on the left.
b.   Add K+Cl-  to the beaker on the left.         
c.   Add ATP to the beaker on the left.
d.   None of these would cause it to happen faster.   D. None of these would cause it to happen faster.
10.   True or False:   If there are a sufficient large number of transport proteins present, glucose can be transported from a solution of lower concentration to a solution of higher concentration (i.e. up its concentration gradient.)   False
11.   Explain one way in which facilitated diffusion is the same as simple diffusion; one way in which it is different.   Facilitated and simple diffusion are similar when concentration gradient.
Simple diffusion happens without the help of membrane proteins and facilitated diffusion needs a membrane bound.
12.   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 greater the concentration difference between one side of the membrane and the other, the greater the rate of facilitated diffusion.
13.   You were asked to predict what effect you thought that adding Na+ Cl- would have on the glucose transport rate.  Why did you pick the choice you did?  How well did the results compare with your prediction?   I predicted that Na+Cl- would have no effect on the glucose due to saturation.
ACTIVITY 3:  Simulating Osmotic Pressure
14.   True or False:  Osmosis is considered a type of passive transport, i.e. it does not need energy from ATP.   True
15.   If a cell is placed in a ________ solution of water, there will be no net movement of water in or out of the cell.
a.   hypotonic
b.   isotonic      
c.   hypertonic   B. Isotonic
16.   If you “cut” the concentration of a non-diffusible solute that is on one side of a membrane in half, the osmotic pressure will
a.   double.
b.   not change.               
c.   be half of what it was before.   C. Be half of what it was before.
17.   Explain the effect that increasing the Na+Cl- concentration had on osmotic pressure and why it has this effect.   Increasing the number of non-diffusible particles increases osmotic pressure. If solutes are able to diffuse, then equilibrium will be established and osmotic pressure will not be generated. Osmotic pressure would be zero if albumin concentration was the same on both sides of the membrane.
18.   Describe one way in which osmosis is similar to simple diffusion; describe one way in which it is different.   Similar because movement of a substance an area of higher concentration to lower with or along or down the concentration gradient. Differ because that diffusion moves particles and ions while osmosis moves only water.
19.   Solutes are sometimes measured in milliosmoles.  Explain this statement: “Water chases milliosmoles.”   Osmosis is the diffusion of the solvent = water.  The water in this simulation diffuses to the side of the membrane that has the highest concentration of the solutes.
20.   The conditions were 9mM albumin in the left beaker and 10mM glucose in the right beaker with the 200 MWCO membrane in place.  Explain the results.   My guess was wrong and the pressure increased on the left.
ACTIVITY 4:  Simulating Filtration
21.   The filtration rate of Na+Cl- in the simulation was dependent on
a.   the pore size of the membrane.
b.   the hydrostatic pressure applied to the top beaker.   
c.   the concentration of the solutes in the lower beaker.
d.   both the pore size and the hydrostatic pressure applied.   D. Both the pore size and the hydrostatic pressure applied.
22.   True or False:  The simulation would not function if the top beaker were open to the atmosphere instead of having pressure applied to the top beaker.        False
23.   Explain in your own words why increasing the pore size increased the filtration rate.  Use an analogy to support your statement.    Because more fluids and solutes can pass through the membrane.
24.   Which solute did not appear in the filtrate using any of the membranes?   activated charcoal
25.   Why did increasing the filtration pressure increase the filtration rate but not the concentration of solutes?   Filtration rate increased because the blood pressure increased.
Concentration of solutes did not increase because the pore size did not increase.
ACTIVITY 5:  Simulating Active Transport
26.   In this simulation, each of the following was (were) required In order for active transport to occur:
a.   sodium ions (Na+)
b.   potassium ions (K+)            
c.   energy from ATP
d.   All of the above were required.   D. All of the above were required.
27.   True or False:  The amount of ATP that you dispensed did not affect the rate that the solutes passed from one beaker to the other.      False
28.   Which of the following processes require ATP?
a.   Simple diffusion
b.   Facilitated diffusion      
c.   Filtration
d.   Osmosis
e.   Active transport   E. Active transport
29.   Describe the significance of using 9mM sodium chloride inside the cell and 6mM potassium chloride outside the cell.   9mMof sodium chloride inside is because 3 ions are ejected for every 2 K that are added.
30.   Explain why there was no sodium transport even though ATP was present.   There were no sodium ions because they were ejected by the cells by active transport.
31.   Explain why the addition of glucose carriers either had no effect or did have an effect on sodium or potassium transport.   Addition had no effect on the sodium and potassium transport due to solute pumps.
32.   Do you think glucose is being actively transported or transported by facilitated diffusion in this experiment.  Why?   Facilitated diffusion.  The glucose could not be actively transported because they are lipid insoluble and too large to pass through the membrane pores.
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5 years ago
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5 years ago
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