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Final

LIFESCI 7A Final: LS7A Final Practice MCExam


Department
Life Sciences
Course Code
LIFESCI 7A
Professor
Maloy
Study Guide
Final

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Chemistry e, c, d, b, a, a, b, a, b
1. Three carbon atoms are linked by single covalent bonds such that they form the shape of a V. All
of the unshared electrons form covalent bonds with hydrogen. How many hydrogen atoms does
this molecule contain?
a. 4
b. 6
c. 2
d. 10
e. 8
2. Refer to the periodic table, and decide which of the following molecules is held together by
a. KCl
b. NH3
c. CH4
3. How many hydrogen atoms are present in a hydrocarbon chain of five carbon atoms with two
double bonds and two single bonds?
a. 6
b. 10
c. 12
d. 8
4. Refer to the periodic table, and decide which of the following molecules is held together by polar
covalent bonds.
a. CH4
b. NH3
c. KCl
5. Consider the molecule shown here (Molecule X). The minus sign next to oxygen represents a full
negative charge on that atom. Answer the following questions about Molecule X.
Molecule X contains at least one nonpolar covalent bond:
a. True
b. False
6. Molecule X could form a hydrogen bond with water:
a. True
b. False
7. Molecule X could form a hydrogen bond with another Molecule X:
a. True
b. False
8. Molecule X could form an ionic bond with Na+:
a. True
b. False
9. Molecule X could cross a phospholipid bilayer
a. True
b. False

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Cell Membrane b, c, b, d, c
10. Why does a phospholipid on the cytoplasmic side of the cell membrane rarely flip to the
extracellular side if both environments are polar?
a. ‘The two sides have different functions and thus the phospholipid would not function
properly.
b. The polar head group cannot pass through the nonpolar interior.
c. The cholesterol does not allow lipids to move.
d. The cytoplasmic phospholipid is too big to pass through the membrane.
11. In the figure below, the cell is _____ to the solution. If the membrane is
permeable to water, but not to solutes, net movement of water will be _____
the cell. (Note that the units mM represent the total concentration of solute
in the solution.)
a. hypertonic: out of
b. hypotonic: into
c. hypotonic; out of
d. hypertonic: into
12. Phospholipase is an enzyme that cleaves the phosphate head group off a phospholipid molecule.
The plasma membrane is not, however, permeable to the enzyme. Imagine a cell where
phospholipid A is present in the layer of phospholipids facing the exterior of the cell, and
phospholipid B is present in the layer of phospholipids facing the interior of the cell. After adding
phospholipase to the medium in which the cell is growing, what would you expect to find in the
fluid surrounding the cell?
a. phosphate head groups from both phospholipids A and B
b. the phosphate head group from phospholipid A only
c. the phosphate head group from phospholipid B only
d. phosphate head groups from neither phospholipids A nor B
13. Which one of the following molecules would MOST likely require a transport protein to cross the
plasma membrane of a red blood cell?
a. H2O
b. CO2
c. O2
d. C6H12O6
14. The beaker in the illustration below contains two solutions of salt with
different concentrations (measured by molarity, M). The two solutions are
separated by a membrane that is permeable to both salt and water.
Which of the following will occur in this container?
a. Diffusion of salt across the membrane, but not of water.
b. Net diffusion of water across the membrane, but not of salt.
c. Net diffusion of water from A to B and of salt from B to A.
d. Net diffusion of water from B to A and of salt from A to B.
e. Net diffusion of salt from B to A, but no net diffusion of water.
Membrane Transport b, b, c, c
15. The diagram below shows a cell with three different membrane
transport proteins. The Na+/K+ Pump is a primary active
transporter and the Na+/Waste Co-transporter is a secondary
active transporter. Arrows show the direction of net movement of
molecules through the Pump and Co-transporter. The Na+

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Channel can exist in either a closed state (no Na+ can pass through) or an open state (Na+ can
pass through). Use this diagram to answer the questions below.
What will happen to the net movement of Waste molecules if the Na+/K+ Pump stops working?
a. Net movement of Waste out of the cell will continue indefinitely (nothing will change)
b. Net movement of Waste out of the cell will continue for some time and then all net
movement of Waste in or out of the cell will stop
c. All net movement of Waste in or out of the cell will stop immediately
d. Net movement of Waste out of the cell will stop immediately and then Waste will be
transported into the cell
e. Net movement of Waste out of the cell will continue for some time and then Waste will
be transported into the cell
16. The concentration of Waste molecules is ________ inside the cell compared to the outside.
a. About the same
b. Lower
c. Higher
17. What will happen when the Na+ channel is open?
a. There will be no net movement of Na+ through the channel
b. There will be net movement of Na+ out of the cell through the channel
c. There will be net movement of Na+ into the cell through the channel
18. Compared to when the Na+ channel is closed, how will the transport of Waste molecules change
when the Na+ channel is open?
The rate of Waste transport out of the cell will:
a. Increase
b. Not change
c. Decrease
19. Refer to the free energy diagrams below to answer the following questions. You may assume that
the y-axis is the same and directly comparable for all four reactions.
Reaction C is endergonic:
a. True
b. False
20. Reaction A should occur at a faster rate than Reaction D:
a. True
b. False
21. Reaction B should be coupled to Reaction D:
a. True
b. False
22. Which of the following examples is considered catabolism? (Select all that apply.)
a. use of fat (triglyceride) stores as a cellular energy source
b. hydrolysis of glycogen (a glucose polymer) during activity
c. synthesis of new DNA copies prior to cell division
d. a person losing weight on a calorie restriction diet
e. fat cells growing bigger during times of ample nutrition
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