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1) My student made a lipid bilayer in the lab that was similar to the plasma membrane of a
cell. She found that changing the concentration of Substance A also changes the fluidity
of the bilayer as illustrated in the graph below. Explain why each answer choice is right
or wrong. Substance A is most likely to be:
a) sites rather than being associated
with high membrane fluidity.
b) phospholipids with carbon double
bonds in hydrocarbon tails(
c) phospholipids with saturated
hydrocarbon tails
d) unsaturated glycoprotein
2) A length of dialysis tubing (which is permeable to water but not glucose) is filled with a 3.0 M
glucose solution. The tubing is tied off and weighed. It is placed in a beaker of unknown
solution. At 10 minute intervals the tubing is removed and weighed again. The experiment and
results are shown to the right. Explain why each answer choice is right or wrong.
a. The solution in the beaker could be
5.0 M glucose
b. The solution in the beaker could be
1.0 M glucose
c. The solution in tubing is hypotonic
compared to the solution in the
beaker
d. Water flow across the tubing stops
at 20 minutes
e. The beaker solution is hypertonic
compared to the tubing solution