FIRST NINE WEEKS EXAM(TAKE HOME)
DUE by 12pm on SATURDAY October 19. Please send to garamir1@episd.org. Your name must be in the
subject line. Any tests submitted (time stamped after 12pm on due date will not be scored).
1. The figure shown depicts the molecular structure of a typical phospholipid bilayer. Which of
the following statements regarding phospholipid bilayers is false?
A. Phospholipids have both hydrophobic and hydrophilic regions.
B. In water, phospholipids tend to aggregate to form a bilayer.
C. Individual phospholipids are free to change sides of the bilayer.
D. The hydrophobic interior of the membrane is an oil-like fluid.
E. The inner and outer halves of a bilayer often differ in phospholipid composition.
2. In the accompanying figure of an integral membrane protein, which of the following groups of
terms correctly describes the three labeled regions (1, 2, 3) of the protein?
A. 1 = hydrophilic; 2 = hydrophobic; 3 = hydrophilic
B. 1 = hydrophobic; 2 = hydrophobic; 3 = hydrophilic
C. 1 = hydrophilic; 2 = hydrophobic; 3 = hydrophobic
D. 1 = hydrophobic; 2 = hydrophilic; 3 = hydrophobic
E. 1 = hydrophobic; 2 = hydrophilic; 3 = hydrophilic
3. Which of the following statements regarding cell–cell adhesion (shown) is false?
A. Proteins on the surfaces of cells are the main mediators of cell–cell adhesion.
B. Oligosaccharides attached to proteins may be the basis for cell–cell adhesion.
C. Oligosaccharides may be attached to membrane lipids.
D. Cell–cell adhesion is important in animal development.
E. Different cells may have different glycoproteins on their surfaces.
4. Which of the following statements regarding the sequence of events shown here is true?
A. The cell in condition C has been immersed in a hypertonic solution.
B. The concentration of solutes inside the cell shown in condition C is higher than the solution
surrounding the cell.
C. The cell in condition A has been immersed in a hypotonic solution.
D. Osmosis occurs when going from condition B to C, but not from B to A.
E. Diffusion of solutes out of the cell is causing the events shown in the transition from condition
B to A.
5. Which of the following statements regarding the sequence of events shown here is true?
A. The cells in condition B have less turgor pressure than the cell in condition A.
B. The cells in condition A have been placed in a hypotonic solution.
C. The cells in condition C have been placed in a hypertonic solution.
D. The cells in condition C have been placed in an isotonic solution.
E. The cells in condition C have greater turgor pressure than the cells in condition B.
6. Which of the following statements regarding channel proteins is false?
A. Channel proteins can assist polar molecules to cross the plasma membrane by facilitated
diffusion.
B. The gated ion channel can allow ions to pass when stimulated to open.
C. The surface of a channel protein in contact with the bilayer would likely have hydrophilic
amino acids.
D. Water plays a role in determining which ions are allowed to pass through an ion channel.
E. Aquaporins facitate the diffusion of water across membranes.
7. The accompanying figure shows
A. simple diffusion of glucose into a cell.
B. active transport of glucose into a cell.
C. facilitated diffusion of glucose into a cell.
D. the accumulation of glucose against its concentration gradient.
E. the gated transport of glucose.
8. Which of the following statements regarding the transport system shown here is false?
A. Both primary and secondary active transport processes are depicted in the diagram.
B. Both primary and secondary active transport processes move substances against their
concentration gradients.
C. Both primary and secondary active transport processes require energy.
D. ATP hydrolysis provides the energy for the generation of both the Na+ and K+ gradients.
E. Both primary and secondary active transport require the activity of a membrane protein.
9. The process in the figure shown is called
A. diffusion.
B. osmosis.
C. facilitated diffusion.
D. endocytosis.
E. exocytosis
10. The process of receptor-mediated endocytosis is shown in the accompanying figure. Which
of the following statements regarding this process is false?
A. Receptor-mediated endocytosis requires receptor proteins located on the cell’s surface.
B. Coated pits are lined on their cytoplasmic surface by clathrin.
C. Receptor-mediated endocytosis is important in cellular uptake of cholesterol.
D. Coated vesicles eventually become part of the endoplasmic reticulum.
E. Coated vesicles contain previously extracellular material.
11. Which of the following statements regarding chemical signaling systems (shown) is false?
A. Autocrine signals have an effect on the cells that secrete them.
B. Paracrine signals have an effect on nearby cells.
C. In larger organisms, circulating signals are carried from the environment to internal cells.
D. In a larger organism, most signals received by cells are chemical in nature.
E. The cells of our body can respond to a diverse array of chemical signals.
12. You are monitoring the diffusion of a molecule across a membrane. An internal
concentration of _______ and an external concentration of _______ will result in the fastest rate
of diffusion.
a. 5; 60
b. 60; 5
c. 35; 40
d. 50; 50
e. Either a or b
13. If a red blood cell with an internal salt concentration of about 0.85 percent is placed in a
saline solution that is 4 percent, the
a. cell will lose water and shrivel.
b. cell will gain water and burst.
c. turgor pressure in the cell will increase greatly.
d. turgor pressure in the cell will decrease greatly.
e. cell will remain unchanged.
14. Solution X is hypotonic relative to solution Y if solution X has a solute concentration that is
_______ solution Y.
a. greater than that of
b. lower than that of
c. the same as that of
d. All of the above
e. None of the above
15. Which of the following statements about osmosis is false?
a. Osmosis refers to the movement of water along a concentration gradient.
b. In osmosis, water moves to equalize solute concentrations on either side of the membrane.
c. The movement of water across a membrane can affect the turgor pressure of some cells.
d. If osmosis occurs across a membrane, then diffusion is not occurring.
e. During osmosis, water is moving through membrane channels.
16. The rate of diffusion can be affected by
a. temperature.
b. molecule size.
c. the concentration gradient.
d. the electrical charge.
e. All of the above
17. The surface area-to-volume ratio of an object can be decreased by
a. cutting it into smaller pieces.
b. flattening it.
c. stretching it.
d. making it spherical.
e. All of the above
18. How does the surface area-to-volume ratio of a 1-mm cube compare to the surface area-tovolume ratio of a 3-mm cube?
a. The 3-mm cube has a higher ratio.
b. The ratio decreases as the cube becomes smaller.
c. An increase in the volume doubles the ratio.
d. The ratio decreases as the cube becomes larger.
e. The ratio does not change.
19. The role of organelles is to
a. provide structural support for the cell.
b. decrease the flow of materials into and out of the cell.
c. increase the efficiency of cellular activities.
d. provide a means of cellular reproduction.
e. regulate the flow of materials inside the cell.
20.What is the difference between “free” ribosomes and “attached” ribosomes?
a. Free ribosomes are in the cytoplasm, whereas attached ribosomes are anchored to the
endoplasmic reticulum.
b. Free ribosomes produce proteins in the cytosol, whereas attached ribosomes produce proteins
that are inserted into the ER.
c. Free ribosomes produce proteins that are exported from the cell, whereas attached ribosomes
make proteins for mitochondria and chloroplasts.
d. Both a and b
e. Both a and c
21. The organelle shown below is found in all cells but is most numerous in cells requiring a
large amount of energy (e.g., liver cells). What is the name of this organelle?
a. Lysosome
b. Golgi apparatus
c. Rough endoplasmic reticulum
d. Mitochondrion
e. Chloroplast
22. Which of the following proteins powers the movement of both cilia and vesicles within a
cell?
a. Myosin
b. Actin
c. Keratin
d. Dynein
e. Kinesin
23. Cilia and eukaryotic flagella
a. propel cells by rotation of the structures.
b. contain microfilaments.
c. contain microtubules that are sufficient to drive movement.
d. must have a motor protein that uses the energy of ATP hydrolysis to power movement.
e. contain centrioles.
24. The presence of _______ means that substances must pass through, rather than between, the
epithelial cells that form the lining of the small intestine.
a. gap junctions
b. tight junctions
c. desmosomes
d. plasmodesmata
e. Both a and b
25. You fill two containers with identical amounts of reactants A and B and enzymes 1–4. In the
reactions shown below, if product D inhibits enzyme 2 and product F is an allosteric stimulator
of enzyme 1, what will be the final result if you add extra product D to the second container?
(Assume that both containers are given enough time for the reactions to go to completion.)
a. The concentration of product C will increase and there will be no change in the concentration
of product F compared to that of the first container.
b. The concentration of reactants A and B will increase relative to the first container.
c. The concentration of product F will increase in the second container because more of D is
converted back to C.
d. The concentration of products E and F will both increase in the second container, since D
inhibits enzyme 2.
e. The concentration of product F will increase relative to the first container, since enzyme 2 will
have been inhibited from converting C into D.
26. You are investigating a newly-discovered species. This organism lives in acidic pools in
volcanic craters where temperatures often reach 100°C and normally stay above 90°C. You
determine that it has a surface enzyme that catalyzes a reaction leading to its protective coating,
and you decide to study this enzyme in the laboratory. At which temperature would you most
likely find optimal activity of this enzyme?
a. 0°C
b. 37°C
c. 55°C
d. 95°C
e. 105°C
27. In the pathway A + B  C + D, enzyme X facilitates the reaction. If compound D inhibits
enzyme X, you would conclude that
a. enzyme X is an allosteric inhibitor of the reaction.
b. compound D is an allosteric stimulator of the reaction.
c. compound D is a competitive inhibitor of the reaction.
d. enzyme X is subject to feedback stimulation.
e. compound D is a coenzyme in the reaction.
28. Metabolism is organized into pathways that are linked in which of the following ways?
a. All cellular functions feed into a central pathway.
b. All steps in the pathway are catalyzed by the same enzyme.
c. The product of one step in the pathway functions as the substrate in the next step.
d. Products of the pathway accumulate and are secreted from the cell.
e. Different substrates are acted on by the same enzyme.
29. Proteins consist of amino acids linked by
a. noncovalent bonds.
b. peptide bonds.
c. phosphodiester bonds.
d. van der Waals forces.
e. Both a and b
30. A disulfide bridge is formed by
a. two cysteine side chains.
b. two glycerol linkages.
c. two proline side chains.
d. condensation.
e. hydrolysis.
31. The double-helix formation of DNA is caused by
a. ionic bonds.
b. covalent bonds.
c. hydrogen bonds.
d. hydrophobic side chains.
e. None of the above
32. This figure shows the effect of pH on the activity of the enzymes pepsin, chymotrypsin, and
arginase. Each enzyme has a different substrate. Consider a solution (solution 1) with equal
concentrations of all three substrates for the three enzymes along with another solution (solution
2) containing all three enzymes. The fastest way to obtain a solution containing only pepsin
substrate (removing the substrates for chymotrypsin and arginase) from solution 1 is to adjust the
pH of solution 1 to _______ and add the enzyme solution (solution 2).
A. 2
B. 5
C. 7
D. 8
E. 10
33. Which statement about enzyme inhibitors and inhibition is true?
A. Noncompetitive inhibitors usually act by binding to the active site.
B. Irreversible inhibition of enzyme activity is rare in cells.
C. A competitive inhibitor competes with the enzyme for substrate binding.
D. An allosteric regulator affects enzyme activity using a mechanism similar to that seen in competitive inhibition.
E. A competitive inhibitor usually binds covalently to the enzyme’s active site.
34. Which of the following statements correctly explains why the reaction rate pattern shown in
the graph for an enzyme–catalyzed reaction differs from the pattern without an enzyme?
A. With an enzyme, reaction rate initially increases rapidly due to increased substrate binding,
but levels off once the enzyme is saturated.
B. To obtain a curve as seen for the catalyzed reaction, the concentration of enzyme must be
lower than substrate.
C. The active site of an enzyme would be saturated with substrate at low substrate
concentrations.
D. The maximum rate of enzyme-catalyzed reactions is a measure of the enzyme’s catalytic
efficiency.
E. The rate of an uncatalyzed reaction is determined by the concentration of the substrate, but the
rate of an enzyme-catalyzed reaction depends on the enzyme concentration.
35. Which of the following statements about the protein shown here is true?
A. Protein tertiary structure is primarily maintained by covalent bonds.
B. This protein has a quaternary structure.
C. The protein shown does not contain any -pleated sheets.
D. The information necessary for correct protein folding is often present in a protein’s primary
structure.
E. Chemicals that disrupt hydrogen bonds and disulfide bridges leave proteins like ribonuclease
permanently denatured.
36. Which of the following statements about the protein segment shown is true?
A. The structure shown is an example of tertiary structure.
B. The structure shown is maintained by hydrogen bonding between amino acid side chains.
C. Disulfide bridges and ionic interactions help maintain the structure shown.
D. The type of structure shown always involves two polypeptides.
E. A protein’s primary structure determines whether or not the structure shown will form.
37. Which of the five labeled bonds is formed by a condensation reaction between two amino
acids?
A. 1
B. 2
C. 3
D. 4
E. 5
Diagram
38. The diagram below shows three amino acids. Which of the following statements about these
amino acids is true?
a. They have charged hydrophilic side chains.
b. They have hydrophobic side chains.
c. They have uncharged polar side chains.
d. They form disulfide bridges.
e. They are smaller than all other amino acids.
39. Consider the two labeled regions (1 and 2) of the phospholipid (phosphatidylcholine) shown
here. Select the choice that makes the following statement true: Region 1 is _______ and would
form the _______ of a cell membrane; region 2 is _______ and would form the _______ of a cell
membrane.
A. hydrophobic; interior; hydrophilic; surface
B. hydrophobic; surface; hydrophilic; interior
C. hydrophilic; surface; hydrophobic; surface
D. hydrophilic; surface; hydrophobic; interior
E. hydrophilic; interior; hydrophobic; interior
40. In the formation of a triglyceride from the components shown (1 and 2), _______
molecule(s) of compound 1 combine(s) with _______ molecule(s) of compound 2 to form a
triglyceride plus _______ molecule(s) of water.
A. 1; 1; 1
B. 1; 3; 1
C. 1; 3; 3
D. 3; 3; 3
E. 3; 1; 3
41. Which of the following statements about polysaccharides or a polysaccharide is true?
A. Polysaccharides are polymers of monosaccharides connected by saccharide linkages.
B. Glycogen is more branched than starch.
C. Starches are polysaccharides of ribose.
D. A starch molecule causes more osmotic pressure than would the unlinked monosaccharides
that make it up.
E. Cellulose is easily broken down because its linkages are not very stable.
42. Which statement about the reaction shown is true?
A. A hexose combines with a pentose to form a disaccharide.
B. Two hexoses combine to form an oligosaccharide.
C. This is a catabolic reaction.
D. This is a condensation reaction.
E. This is a hydrolysis reaction.
43. Macromolecules contain functional groups that affect the molecule’s chemical properties.
Use your understanding of chemical bonds to determine which of the following functional
groups could form hydrogen bonds with water.
A. The hydroxyl group
B. The aldehyde group
C. The carboxyl group
D. The phosphate group
E. All of the above
44. Which example shown (A–E) depicts the correct distribution of charge and hydrogen
bonding between two water molecules?
A. Example A
B. Example B
C. Example C
D. Example D
E. Example E