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Lecture 3

BIOL 1201 Lecture Notes - Lecture 3: Winter Wheat, Hydrophile, Facilitated Diffusion


Department
Biological Sciences
Course Code
BIOL 1201
Professor
Moroney, James
Lecture
3

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Biology 1201-4, Exam 2, 9 October 2012
Version 1
Make sure that your name (LAST NAME FIRST) and student ID number are on the
answer sheet and the circles are filled under them. Also fill in which version of the exam
you are taking. You may keep your copy of the exam. Answers and grades will be posted
in Moodle.
*ANSWERS
Chapter 7
1) When biological membranes are frozen and then fractured, they tend to break along the
middle of the bilayer. The best explanation for this is that
A) the integral membrane proteins are not strong enough to hold the bilayer together.
B) water that is present in the middle of the bilayer freezes and is easily fractured.
C) hydrophilic interactions between the opposite membrane surfaces are destroyed on freezing.
D) the carbon-carbon bonds of the phospholipid tails are easily broken.
*E) the hydrophobic interactions that hold the membrane together are weaker than hydrophilic
interactions.
2) According to the fluid mosaic model of cell membranes, which of the following is a true
statement about membrane phospholipids?
*A) They can move laterally along the plane of the membrane.
B) They occur in an uninterrupted bilayer, with membrane proteins restricted to the surface of
the membrane.
C) They are free to depart from the membrane and dissolve in the surrounding solution.
D) They have hydrophilic tails in the interior of the membrane.
3) Which of the following is one of the ways that the membranes of winter wheat are able to
remain fluid when it is extremely cold?
*A) by increasing the percentage of unsaturated phospholipids in the membrane
B) by decreasing the number of hydrophobic proteins in the membrane
C) by co-transport of glucose and hydrogen
D) by using active transport
4) In order for a protein to be an integral membrane protein it would have to be which of the
following?
A) hydrophilic
B) hydrophobic
*C) amphipathic
D) completely covered with phospholipids
E) exposed on only one surface of the membrane
5) Of the following functions, which is most important for the glycoproteins and glycolipids of
animal cell membranes?
A) facilitated diffusion of molecules down their concentration gradients
B) active transport of molecules against their concentration gradients
C) maintaining the integrity of a fluid mosaic membrane
D) maintaining membrane fluidity at low temperatures
*E) a cell's ability to distinguish one type of neighboring cell from another
6) What kinds of molecules pass through a cell membrane most easily?
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A) large and hydrophobic
*B) small and hydrophobic
C) large polar
D) ionic
E) monosaccharides such as glucose
7) Which of the following statements is correct about diffusion?
A) It is very rapid over long distances.
B) It requires an expenditure of energy by the cell.
*C) It is a passive process in which molecules move from a region of higher concentration to a
region of lower concentration.
D) It is an active process in which molecules move from a region of lower concentration to one
of higher concentration.
E) It requires integral proteins in the cell membrane.
8) A patient has had a serious accident and lost a lot of blood. In an attempt to replenish body
fluids, distilled water, equal to the volume of blood lost, is transferred directly into one of his
veins. What will be the most probable result of this transfusion?
A) It will have no unfavorable effect as long as the water is free of viruses and bacteria.
B) The patient's red blood cells will shrivel up because the blood fluid is hypotonic compared to
the cells.
*C) The patient's red blood cells will swell because the blood fluid is hypotonic compared to the
cells.
D) The patient's red blood cells will shrivel up because the blood fluid is hypertonic compared to
the cells.
E) The patient's red blood cells will burst because the blood fluid is hypertonic compared to the
cells.
9) The movement of potassium into an animal cell requires
A) low cellular concentrations of sodium.
B) high cellular concentrations of potassium.
*C) an energy source such as ATP.
D) a cotransport protein.
E) a gradient of protons across the plasma membrane.
10) An organism with a cell wall would have the most difficulty doing which process?
A) diffusion
B) osmosis
C) active transport
*D) phagocytosis
E) facilitated diffusion
Chapter 8
11) Which of the following is likely to lead to an increase in the concentration of ATP in a cell?
A) an increase in a cell's anabolic activity
*B) an increase in a cell's catabolic activity
C) an increased influx of cofactor molecules
D) an increased amino acid concentration
E) the cell's increased transport of materials to the environment
12) Which of the following is an example of potential rather than kinetic energy?
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A) H+ flowing through ATP Synthase
B) Electrons moving through an electron transport chain
C) A firefly using light flashes to attract a mate
*D) Electrons in a protein
E) Electrons in CO2
13) When glucose monomers are joined together by glycosidic linkages to form a cellulose
polymer, the changes in free energy, total energy, and entropy are as follows:
A) +G, +H, +S
*B) +G, +H, -S
C) +G, -H, -S
D) -G, +H, +S
E) -G, -H, -S
14) Which is least stable
A) CO2
B) H2O.
C) Glucose
*D) Saturated fat
15) When Glutamic acid is phosphorylated by ATP, what happens?
A) Glutamic acid becomes less reactive
*B) Glutamic acid becomes more reactive
C) Glutamic acid breaks down
D) Entropy of glutamic acid decreases
16) What would happen if enzymes did not mediate catabolic, exergonic reactions of large
molecules in organisms?
A) The reactions would never happen
B) The reactions would occur slowly
C) The molecules would become more stable
D) The molecules would lose their potential energy
*E) All their energy would be lost as heat
17) During a laboratory experiment, you discover that an enzyme-catalyzed reaction has a G of
-20 kcal/mol. If you double the amount of enzyme in the reaction, what will be the G for the
new reaction?
A) -40 kcal/mol
*B) -20 kcal/mol
C) 0 kcal/mol
D) +20 kcal/mol
E) +40 kcal/mol
18) Which of the following metabolic processes can occur without a net influx of energy from
some other process?
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