Download SI Practice Exam / Review Sheet

SI Practice Exam / Review Sheet
Part 1 Select the appropriate word or words for each of the following.
1. Cells that perform the same function are called a/an _______________, and
different types of cells with a similar function make up
a/an____________________.
2. Adjacent plant cells are held together by a central layer of gelatinous pectins
between primary cell walls called ____________________.
3. The location on an enzyme where substrates bind and react is called
_________________.
4. The concentration of ligand at which fifty percent of receptors are bound is
known as the _____________________.
5. A protein that becomes functional after undergoing a conformational change is
a/an ________________ protein.
6. Protein Kinase A is activated by ______________.
7. In metabolism, synthesis is an example of _________________ and digestion is
an example of _____________________.
8. Enzyme activity is regulated by ______________________,
__________________ and ______________________.
9. In a ____________ reaction something gains electrons from something that
donates electrons.
10. During glycolysis in cellular respiration the molecule ___________ gets reduced
while glucose is oxidized.
11. The process of glycolysis yields _______ net ATPs.
12. The delta G of digesting one mole of glucose is _____________ kcal/mol.
13. Coupled reactions make __________________ reactions possible under
biological conditions.
14. If a molecule contains high free energy its stability is ___________.
15. The process of transferring phosphate groups from high-energy donor molecules,
such as ATP, to specific target molecules, substrates, is known as
__________________.
Part 2 Multiple Choice
1. In the g-protein linked receptor cascade, the g-protein is activated when the alpha
subunit splits from the two smaller subunits and is bound by ____________.
a. GDP
b. STAT
c. GTP
d. a phosphate
2. A tyrosine kinase receptor binds its ligand. The complete receptor is a dimmer and the
two monomers that make up the dimmer cross phosphorylate. What happens next?
a. STAT monomers are phosphorylated.
b. STAT monomers detach from the receptor.
c. Two STAT monomers bind the receptor.
3. In animals ______________ are formed when membrane proteins from adjacent cells
line up to form a channel.
a. Tight junctions.
b. Desmosomes
c. Tubules
d. Gap junctions.
4. At low substrate concentrations, enzyme-catalyzed reaction rates __________ as
substrate concentration increases, and at high substrate concentrations, enzyme-catalyzed
reaction rates ____________.
a. Show an exponential increase: increase linearly.
b. Increase linearly; increase linearly.
c. Decrease linearly; plateau at a maximum speed.
d. Increase linearly; plateau at a maximum speed.
5. In a specific instance of cell-to-cell communication a ligand, or chemical messenger, is
hydrophilic. What is true about the receptor this ligand will bind to?
a. It is intercellular.
b. It will bind steroids.
c. It is extracellular.
d. None of the above.
6. Which of the following are shared by cells connected by gap junctions? Choose all that
apply.
a. Ions.
b. RNA.
c. Amino acids.
d. Smooth ER.
e. Nucleotides.
7. A receptor is desensitized due to receptor down regulation. What is a possible result of
this?
a. A tolerance may be developed.
b. Response to a steady [ligand] will go up.
c. Nothing will happen.
d. Glycolysis can not take place.
8. A particular reaction converts biological molecule A to biological molecule B with a
delta G of -5.5kcal/mol. Which of the following statements is true?
a. A is more stable than B.
b. B has more energy than A.
c. The transition state of this reaction is less stable than either A or B.
d. The transition state of this reaction has less energy than either A or B.
9. In the G-protein linked receptor cascade the G-protein has just been activated. What
happens next?
a. cAMP can activate PKA.
b. Adenylate cyclase can be activated.
c. An ATP is converted to ADP and a phosphate group.
d. Nothing, the cascade is complete.
10. A dye injected into a plant cell might be able to enter an adjacent cell through a
a. Microtubule.
b. Cell wall.
c. Plasmodesmata.
d. Tight junction.
11. What is the first step in the tyrosine kinase receptor cascade?
a. The active dimmer undergoes cross phosphorylation.
b. A T-cell releases an interleukin.
c. IL4 binds the inactive monomers.
d. A B-cell makes an antibody.
12. Imagine that resonance stabilization was not a factor in ATP and its hydrolysis to
ADP and a phosphate. In other words, only charge repulsion explained the high energy
phosphoanhydride bonds. Which of the following would therefore be true?
a. The delta G for ATP hydrolysis would be -7.3kcal/mol.
b. The delta G would be more negative than -7.3kcal/mol.
c. The delta G would still be negative, but less negative than -7.3kcal/mol.
d. The delta G would be positive.
13. A kcal is the amount of energy required to raise the temperature of _________ g of
____________ by _________ degree Celsius.
a. 10; water; 1000
b. 1000: ethanol; 1
c. 7.3; water; 686
d. 1000; water; 1
14. Antifreeze, which contains methanol, is said to taste sweet. Little Tommy decides
that this is awesome and chooses to drink some of it. The bad thing is when we ingest
methanol our bodies turn it into formaldehyde (which can be deadly). Poor little Tommy
is rushed to the hospital and put on an ethanol drip. The ethanol helps to inhibit the
methanol from interacting with a specific enzyme, alcohol dehydrogenase, through
competitive inhibition to slow the process of the conversion of methanol to
formaldehyde. From this account you could logically conclude that:
a. Ethanol binds to an allosteric site on the enzyme, causing it to lose its active
conformation.
b. Tommy listened carefully to his mom when she said not to drink the antifreeze
or else.
c. Ethanol binds to an allosteric site on the enzyme, causing the active site to
form.
d. Ethanol binds to the active site, but is not converted to formaldehyde.
15. How do enzymes lower activation energy?
a. Raise effective concentrations of reagents.
b. Orient reactive groups in a way that helps the reaction.
c. Provide right microenvironment.
d. Move reagents to transition state.
e. All of the above.
16. Which of the following is not an exothermic reaction?
a. Burning Sugar.
b. Mixing water and strong acids.
c. splitting a gas molecule.
d. Making ice cubes.
17. Where does glycolysis occur in the cell?
a. Mitochondria.
b. Cytoplasm.
c. Nucleus.
d. None of the above.
18. Which of the following statements is true?
a. All enzymes function best in the neutral pH range.
b. The best enzymes are not affected by temperature and pH.
c. Sometimes enzymes have different versions with different temperature and pH
optima.
d. pH helps enzymes by stabilizing the transition state.
19. What is the general class of enzymes that stick a phosphate group on something?
a. Dehydrogenase.
b. Kinase.
c. Isomerase.
d. All of the above.
20. What is the general class of enzymes that catalyze redox reactions?
a. Dehydrogenase.
b. Kinase.
c. Isomerase.
d. None of the above.
21. Which of the following are true about the animal cell extracellular matrix (ECM)?
Choose all that may apply
a. Composition and amount of ECM varies widely among different types of cells.
b. Protein-protein attachments link the cell cytoskeleton to the ECM.
c. The ECM helps maintain cell turgor pressure.
d. Collagen is the most common ECM protein fiber.
22. In step three of glycolysis, phosphofructkinase can be allosterically inhibited by
what?
a. ATP
b. GTP
c. NAD+
d. GSP
23. _____________ is when you phosphorylate something using a phosphate from a
substrate.
a. Oxidative phosphorylation.
b. Hydrogenation.
c. Catabolism.
d. Substrate level phosphorylation.
24. In the absence of oxygen cellular respiration cannot continue past glycolysis. Instead
fermentation takes place. In fermentation, pyruvate is
a. Oxidized
b. Reduced
c. Excreted.
d. Converted to glucose.
Part 3 Short Answer
1. You have completed biology 201 and have made it to medical school. As an
intern you are asked to treat a patient who has come in with terrible muscle and
stomach cramps and diarrhea that looks like “rice water” (don’t ask me, it’s just a
typical symptom). You determine that the patient has cholera. What causes this?
How should it be treated?
2. You are sitting in the SUB eating lunch one day when you read in the paper that
there was an attempted terrorist attack with Sarin somewhere in Europe. Sarin is
extremely dangerous because it covalently binds to one of the residues in the
active site of the enzyme that causes acetylcholine to hydrolyze. With a build-up
of acetylcholine in the synapse it continues to act so that any nerve impulses are,
in effect, continually transmitted. This initially causes a runny nose and
constriction of pupils. Before you know it people completely lose control over
their bodily functions and they begin to have difficulties breathing, vomit,
defecate, and urinate which eventually leads to death. Why does this covalently
binding of the enzyme cause such destruction?