Biology 190 Exam 2
Henderson Afternoon Section, Fall 2001
Note: I am posting this old exam on our class web page w/o providing an answer key except that I have explained the answers to what I consider the more difficult questions. Your text and CD have questions with answer keys; I suggest that you do those problems first and then do these problems and analyze for yourself—with the help of the book if necessary—whether you got them right or wrong. If you get stuck you can call or e-mail me or talk to me about any questions you have for a specific question from this exam.
Part I (36 multiple choice questions, each worth 2.5 pts. for a total of 90
pts.
1. Enzymes are described as catalysts which means
that they:
a. Are
proteins
b. Provide activation energy for the reactions they facilitate
c. Change
the rate of reaction w/o being consumed by the reactions
d.
Stabilize molecules in the transition state
e.
Elevate the EA barrier so the molecule will not spontaneously degrade
Note: It’s true that enzymes are proteins. But the question really asks what does it mean to be a catalyst. So “a” is wrong. “B” is close but also wrong; catalysts are not suppliers of energy; rather they lower the energy of activation. “C” is correct.
2. ___is an example of the cellular work accomplished with
the free energy of ATP hydrolysis:
a.
Mechanical work such as beating cilia
b.
Transport work such as the movement of glucose against a concentration gradient
into a cell
c.
Chemical work such as protein synthesis
d.
Mechanical work such as pumping blood thru the circulatory system
e. All
of the above
3. Which of the following reactions would be endergonic?
a. HCL to
H+ and Cl-
b. Sugar
+ oxygen to carbon dioxide and water
c. ATP to
ADP plus a phosphate
d.
Glucose plus fructose to sucrose
e. All
of the above
Note: Think! Which will require energy? You should know that HCL is an ionic compound and that ionic compounds readily disassociate into ions easily. Perhaps, I should’ve added “in the presence of water” to answer “a.” So, “a” won’t require energy. You should recognize that sugar + oxygen to carbon dioxide and water is the respiration formula and respiration gives off energy. So, “b” also isn’t the answer. You certainly ought to know that ATP is the main energy currency of a cell and that it releases energy when it splits into ADP and P so “c” can’t be the answer. Having eliminated “a”, “b”, and “c” it’s obvious that “e” can’t be right so “d” has to be the answer. And, you might also remember that “d” is correct because glucose and fructose are monosaccharides so sucrose has to be a disaccharide and it takes energy to link monomers together to form biological polymers.
4. Which of the following characteristics is NOT
associated with allosteric regulation of an enzyme’s activity?
a. A
molecule mimics the substrate and competes for the active site
b. A
naturally occurring molecule stabilizes a catalytically active conformation
c.
Regulatory molecules bind to a site removed from the active site
d.
Inhibitor and activator molecules may compete with one another
e. The
enzyme usually has a quaternary structure
Note: If you know the definition of allosteric this one is easy. If not, maybe you could guess that “a” and “c” are opposites and both can’t be true so the answer is probably “a” or “c” so you’ve increased your guessing odds from 1:5 to 1:2.
5. Which of the following is NOT an explanation of
how an enzyme might work?
a. The
enzyme creates a favorable microenvironment with respect to pH
b. The
enzyme’s active site provides a template for two reactants to come together in
the proper orientation
c.
The enzyme supplies energy to speed up a reaction
d. The
enzyme may briefly covalently bond to one of the substrates
e. The
enzyme’s active site may stress a bond in the substrate that must be broken for
the reaction to occur
6. Which statement is FALSE?
a.
Feedback inhibition is the switching off a metabolic pathway by its endproduct.
b. An
organic co-factor of an enzyme is called a co-enzyme
c.
Metabolism is the sum of catabolism and anabolism
d.
Anabolism is the breaking down of large molecules into smaller molecules
e. Most
vitamins are co-enzymes or raw materials from which co-enzymes are made
7. A sugar cube dropped into a cup of hot water will
dissolve; the sugar in sweetened hot water doesn’t spontaneously all
come together to form a sugar
cube. This observation is best explained as follows:
a.
According to the first law of thermodynamics energy can neither be created nor
destroyed
b. Entropy is a measure of disorder or randomization and the universe is
constantly becoming more disordered or
randomized
c. Sugar
is organic because it has a carbon backbone and water is inorganic and there is
a mutual attraction of
opposites
d. The observation is meaningless because if you wanted to separate the sugar
back out all you would have to do
boil the water off and you’d be left with pure sugar
Note: “b” is correct but a lot a lot of students got this question wrong. Think of entropy this way: Suppose you have a jar of black sand and a jar of white sand. If you mix them together it would be one heck of a problem to separate them back into separate piles of black sand and white sand. It’s easier to mix (or disorder) the sand than it is to separate (or order) the sand. Entropy is a measure of disorder and the natural tendency of things to become more disordered gives rise to the rule (The Second Law of Thermodynamics) that the total entropy of the universe is increasing.
8. You would expect a cell with an extensive Golgi
apparatus to
a.
Make a lot of ATP
b.
Secrete a lot of material
c.
Move actively
d.
Perform photosynthesis
e.
Store large quantities of food
9. In which of the following groupings of organelles is
every member of the group directly involved in manufacturing
substances needed by the cell?
a.
Lysosome, vacuole, ribosome
b.
Ribosome, rough ER, smooth ER
c.
Vacuole, rough ER, smooth ER
d. Smooth
ER, ribosome, cilia
e. Rough
ER, lysosome, flagella
10. Cyanide binds with at least one of the molecules
involved in the production of ATP. Following exposure of a cell to
cyanide, most of the
cyanide could be expected to be found within the
a.
Ribosomes b.
Peroxisomes c. Endoplasmic
reticulum d.
Mitochondria e. Lysosomes
Note: We never discussed cyanide in class before this exam. But this is really an easy question.
11.Which type of organelle is primarily involved in the
synthesis of lipids?
a.
Lysosomes
b. Contractile
vacuoles
c. Ribosomes
d. Smooth endoplasmic
reticulum
e. Mitochondria
12. Which type of cell would probably provide the
best opportunity to study lysosomes?
a. Muscle
cell
b. Nerve
cell
c. Phagocytic white blood cell
d. Leaf cell of a
plant
e. Bacterial cell
13. Which organelle would you expect to find in all
eukaryotic cells?
a.
Cilia
b.
Tonoplast
c. Choroplast
d.
Mitochondria
e. Cell wall
14. Cilia work by:
a. The
cell membrane contracts causing a whip like motion; ATP provides energy
b. The
ribosomes rotate to rotate the cilia; amino acids provide energy
c. The
basal bodies of the cilia rotate to rotate the cila; ATP provides rotation
energy
d.
Desmosomes whip the cilia back and forth; NADH provides energy
e. The
dynein arms of adjacent microtubules uses ATP to cause one microtubule to slide
against another
15. The concentration of calcium in a cell is 0.3%. The
concentration of calcium in the surrounding fluid is 0.1%.
How could the cell
obtain more calcium?
a.
Passive transport
b.
Diffusion
c. Active transport
d.
Osmosis
e. All of the above
16. The concentration of solutes in a red blood cell is
about 2%. Sucrose cannot pass through the membrane, but water
and urea can. Osmosis would cause
red blood cells to shrink the most when immersed in which of the following
solutions?
a. A
hypertonic sucrose solution
b. A
hyptotonic sucrose solution
c. A
hypertonic urea solution
d. A
hypotonic urea solution
e. Pure
water
17. According to the fluid mosaic model of membrane
structure, proteins of the membrane are mostly
a. Spread
in a continuous layer over the inner and outer surfaces of the membrane
b.
Confined to the hydrophobic core of the membrane
c.
Randomly oriented in the membrane with no fixed inside-outside polarity
d.
Embedded in a lipid bilayer
e. Free
to depart from the fluid membrane and dissolve in the surrounding solution
18. Co-transport of sucrose does NOT involve the
following:
a. A
membrane potential ( voltage across the membrane)
b.
Transmembrane proteins
c.
Diffusion of H+ ions
d. ATP
e.
Pinocytosis
19. A cell “desires” to bring into its cytoplasm from the
surrounding fluid some very large dissolved molecules
(for example, soluble
proteins); to do so it will likely engage in:
a.
Exocytosis
b.
Phagocytosis
c.
Pinocytosis
e. Active
transport
d. Passive transport
20. Which of the following will be least likely to
pass through a cell membrane in the absence of special pores
or membrane proteins?
a. Water
b.
Glucose
c. Ethanol (which is a small polar molecule)
d. Ions
e. Carbon
dioxide
21. The concept of a second messenger involved in cell to
cell signalling can best be explained as follows:
a. The
signal molecule from the first cell causes a change in a transmembrane protein
in the receiving cell and as a
result a different molecule, such as C++ or cAMP, called the second messenger,
present in the extracellular fluid,
enters the cell and causes a response
b. Cell A
sends a chemical signal to Cell B; Cell B sends a different chemical signal,
called the second messenger, to
Cell C and Cell C responds
c. In
order for the responding cell to avoid wasteful responses, it won’t respond
unless it receives a chemical signal
from at least two different other cells. The second signal it receives is called
the second messenger
22. Most of the ATP produced in cellular respiration comes
from
a.
Glycolysis
b.
Chemiosmosis
c. Lactic
acid fermentation
d. The
conversion of pyruvate to AcetylCoA
e. The
Calvin cycle
23. The ATP synthase in a human cell gets energy for
making ATP directly (most immediately) from
a.
Sunlight
b. Flow of H+ through a membrane
c.
Oxidation of glucose
d.
Movement of electrons through a series of carriers
e.
Reduction of oxygen
Note: Ouch! I had to think for a moment when reviewing this exam. Respiration involves all of the answers except “sunlight.” The key to getting the correct answer here is to remember how ATP synthase works: it’s the turbine like intermembrane protein whose spin makes ATP and whose spin is driven by the flow of H+ ions thru the membrane.
24. Which of the following is a true distinction between
fermentation and cellular respiration?
a. Only
respiration utilizes glucose
b. NADH
is oxidized (converted back to NAD+) by the electron transport chain only in
cellular respiration
c.
Fermentation, but not cellular respiration, is an example of a catabolic pathway
d.
Substrate level phosphorylation is unique to fermentation
e.
Fermentation occurs only in chloroplasts
Note: Ouch! This is another question that requires a careful reading. “b” is correct. BUT, it is true that fermentation also converts NADH back into NAD+. However, the electron transport chain is unique to cellular respiration.
25. The final electron acceptor of the electron transport chain that functions in oxidative phosphorylation is
a. Oxygen b. NAD+ c. Water d. ATP e. Pyruvate
26. Which of the following is the correct
statement?
a.
Cellular respiration produces about 5 times more ATP per molecule of glucose
than does fermentation
b. In the
absence of oxygen, human cells and yeast cells can engage in fermentation; human
cells convert
glucose to lactic acid and yeast cells convert glucose to carbon dioxide and
ethanol
c. In the absence of oxygen, yeast cells and some human cells can engage in
fermentation; other human cells
cannot engage in fermentation or make ATP in the absence of oxygen
d. Under
ideal conditions about 2 molecules of ATP can be made from each NADH
e. In
humans the various cells are supplied ATP transported to them by the blood
Note: This question is a bit picky. If you’re studying this you should remember the following: 1) The cells in the human body are supplied glucose in the blood; they have to make their own ATP, and 2) Only some human cells such as muscle cells can make ATP in the absence of oxygen; other human cells, such as brain cells, lack this ability; this is why the brain suffers irreversible damage so quickly when deprived of oxygen.
27. The inner membrane of the mitochondria
a. Serves
to keep a high concentration of H+ ions in the intermembrane space
b. Serves
to help arrange the different molecules of the electron transport chain in the
right order
c.
Contains phospholipids and proteins
d. All
of the above
e.
None of the above
Note: Suppose you, like me, have trouble remembering whether the H+ ions in the mitochondrion are concentrated in the intermembrane space or the matrix. Then you wouldn’t know if “a” is correct. But you should remember that “b” is correct and “c” is a safe bet for all membranes. So, if “b” and “c” are correct than the right answer has to be “d.”
28. Facultative anaerobes are organisms that
a.
require oxygen
b.
are killed by oxygen
c.
make the oxygen they consume
d.
require oxygen but on balance produce more oxygen than they consume
e.
make ATP by aerobic respiration if oxygen is present and make ATP by
fermentation if oxygen is not present
29. Which of these wavelengths is least useful for
photosynthesis
a.
Blue b.
Violet c.
Green d.
Red e. Yellow
30. Which of the following correctly matches each of the
inputs of the Calvin cycle with its role in the cycle
a. Carbon
dioxide: carbon ATP:energy
NADPH:fermentation
b. Carbon
dioxide: carbon ATP:energy NADPH:high energy electron
c. Carbon
dioxide: high energy electron ATP:carbon NADPH:energy
d. Carbon
dioxide: energy ATP:carbon NADPH: high energy electron
e. Carbon
dioxide: carbon ATP: hydrogen NADPH:energy
Note: I didn’t stress the difference in my lectures between a high energy molecule and a high energy electron. Even so, if you just grasp the very basic idea that carbon dioxide contributes carbon and ATP and NADPH contribute energy to the Calvin cycle, answer “b” will be obvious.
31. In mechanism (the way it works)
photophosphorylation is most similar to:
a.
Substrate phosphorylation in glycolsysis
b.
Oxidative phosphorylation in cellular respiration
c. The
Calvin cycle
d. Carbon
fixation
e. Reduction of NADP+ (conversion to NADPH)
32. Which of the following statements is a correct
distinction between autotrophs and heterotrophs
a. Only
heterotrophs require chemical compounds from the environment
b.
Cellular respiration is unique to heterotrophs
c. Only
heterotrophs have mitochondria
d.
Autotrophs, but not heterotrophs, can nourish themselves beginning with carbon
dioxide and other nutrients
that are entirely inorganic
e. Only
heterotrophs require oxygen
33. Oxygen in our atmosphere is due to which part of
photosynthesis:
(Give the most
precise--most specific--answer.)
a. Calvin
cycle
b.
Photosystem I
c.
Photosystem II
d. Dark
reactions
e. Light reactions
34. Photorespiration is
a. How
plants burn glucose to get energy
b. A way
that plants can get energy out of half-finished products of the Calvin cycle
c. An
apparent “problem” that appears to deprive many plants of energy under hot,
sunny conditions
d.
Chemiosmosis using light as the energy source instead of food molecules
e.
Something that occurs in some plants when they are deprived of light
35. When the sun is out which type of plant is most likely
to have its stomata closed?
a. C4 plants
b. C3 plants
c. Rice plants
d. CAM plants
e. Corn plants
36. The reactions of the Calvin Cycle require all of the
following except
a.
NADPH
b.
CO2
c.
Glucose
d.
Rubisco
e. ATP
Part II (Essay-10pts.)
Write an essay on the back of the Scantron--you won’t need additional paper--on ONLY ONE of the following topics. Questions with an * after their numbers are harder and will be graded on the basis that there are 12 possible points so you can miss 1/6 of the question w/o penalty. However, even for a perfect answer on the harder questions the maximum number of points is 10.
1*. Explain how chemiosmosis works in both cellular respiration and photosynthesis defining or using in correct context the following: photophosphorylation, oxidative phosphorylation, electron transport chain, ATP synthase, Kreb’s cycle, intermembrane space, matrix, stroma, thylakoid space, ATP, NADH, chloroplast, and mitochondria.
2*. Explain how under ideal circumstances a cell gets 38 ATP from one molecule of glucose in cellular respiration.
3*. Discuss photosynthesis defining or using in correct context the following: PSI, PSII, cyclic electron flow, non-cyclic electron flow, photophosphorylation, electron transport chain, ATP, NADPH, ATP synthase, thylakoid space, stroma, Calvin cycle, dark reactions, light reactions.
4*. Discuss the differences among C3, C4 and CAM plants with respect to photorespiration. Be sure to include a discussion of: 1) how atmospheric carbon dioxide is incorporated into an organic molecule, 2) relevant specialized structures, and 3) whether stomata are open in the day or evening.
5*. Draw a “typical” eukaryotic cell (plant or animal, your choice but label which you have drawn) and label and draw as many organelles as you can and then write a few word description of what each organelle does. You may label subparts of organelles. An excellent answer will have 12 organelle or organelle subparts.
6. Draw and label a typical plant cell in hypertonic, isotonic, and hypotonic
solution (3pts.) AND
Draw and label a typical animal cell in
hypertonic, isotonic, and hypotonic solution (3pts.)
(In each of the 6 cases
show what happens to the cell--included in the above 6 pts.) Define: diffusion,
osmosis, active transport and passive transport (4pts.)
7*. Explain co-transport of sucrose defining or using in correct context: H+ ion pump, ATP, active transport, membrane potential (voltage).
8. Define enzyme, co-enzyme, co-factor, vitamin, and catalyst (1 pt. for each
definition) and discuss what relationships, if any, there are among the terms
(5pts).