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Western University
Biology 1202B
Richard Gardiner

February 2011 Biology 1002B Page 1 of 7 Circle the best single letter choice for each of the following questions before transferring your answers to your computer sheet. Note: All questions have 4 choices. 1. The Miller Urey experiment was a breakthrough in our understanding of the origins of life. However, which of the following questions was not answered by the Miller-Urey experiment? A. How could purine and pyrimidine bases have been synthesized outside of cells? B. How could amino acids have been synthesized in the absence of H 2O? C. How did the racemization of biologically important molecules occur? D. How did cells come to synthesize only one form of each amino acid? 2. Which of the following molecules was absent from the Earth’s atmosphere when life first evolved? A. H 2O B. O 2 C. H 2S D. NH 3 3. The hypothesis of an "RNA World" (in which RNA played the roles of modern DNA, RNA and protein) is now widely accepted as correct. Which of the following discoveries was most significant in supporting the RNA World concept? A. That some RNA molecules can catalyze reactions. B. That RNA, like DNA can be double-stranded. C. That some RNA molecules can encode proteins. D. That ribosomes contain RNA. 4. Which of the following statements about the origins of life are correct? 1. The Earth is estimated to be between 4 and 5 billion years old.
 2. The hypothesis of Panspermia is supported by the discovery of extremophiles. 3. Meteorites have been found that contain amino acids. 4. In laboratory experiments clay has been shown to accelerate the formation of lipid vesicles. 5. DNA is more resistant to breakdown than RNA A. 2and4 B. 1, 2 and 3 C. 1, 3, 4, 5 D. All of the above statements are correct 5. Which measurement is the transit method for detecting extrasolar planets based on? A. Detecting the gravitational influence of a planet on its parent star. B. Detecting periodic shifts in apparent brightness of stars. C. Detecting evidence of water in the spectra of stars. D. Directly observing planets using powerful optical telescopes. Student Number __________________________ Code 222 Code 222 Code 222 February 2011 Biology 1002B Page 2 of 7 6. If water was a nonpolar molecule, which of the following physical characteristics would it have? A. It would have zero heat capacity. B. It would sublimate at lower temperatures. C. It would form hydrogen bonds with other molecules. D. It would be a solid at temperatures found on Earth. 7. While some of the values used for the Drake Equation parameters are very good estimates, others are essentially guesses. Which of the following values for Drake Equation parameters has the least scientific support? A. fc = 0.1 B. f = 0.5 p C. n e= 2 D. N s= 100 billion 8. When it comes to searching for extra-terrestrial intelligence, the term "communicating civilization" is important. How old is our "communicating civilization”? A. 10years B. 100years C. 500years D. 150,000years 9. Which of the following statements best compares the enzymes found in psychrophilic (low temperature adapted) organisms with those found in mesophiles or thermophiles? A. Psychrophilic enzymes contain a greater proportion of hydrophilic amino acids. B. Psychrophilicenzymesare more resistant to denaturation by urea treatment. C. Psychrophilic enzymes are more flexible at their optimal growth temperature. D. Psychrophilic enzymes have a tertiary structure based on weaker bonding arrangements. 10.Which of the following statements about a denatured protein is correct? A. It can never regain the native conformation B. It lacks any primary structure. C. It is of higher energy state than the native conformation. D. Its hydrophobic residues are buried, away from water. 11.Which one of the following genes is not constitutively expressed? A. Pyruvate dehydrogenase complex kinase in humans. B. Hemoglobin apoprotein in humans. C. Light harvesting proteins of the Chlamydomonas chloroplast. D. Cytochrome c oxidase in mice. 12.For a given gene, high rates of transcription do not necessarily lead to correspondingly high rates of translation. Why not? A. High rates of protein turnover in the cytosol. B. Inhibition of transcription factor binding. C. Increase in rate of mRNA decay. D. Increase in transcript abundance. Student Number __________________________ Code 222 Code 222 Code 222 February 2011 Biology 1002B Page 3 of 7 13.Which of the following statements about thermodynamics is correct? A. Closed systems will never reach equilibrium. B. We need to eat food to maintain high entropy. C. Living things are always at equilibrium. D. Substances that are stable have low free energy. 14.Under what condition is Anfinsen’s Dogma often not true? A. When ATP is not available. B. In a living cell. C. When urea is removed from a solution of denatured proteins. D. When a protein is dissolved in a buffer at low concentrations. 15.Why doesn’t a bag of sugar (sucrose) readily break down into CO and2H O? 2 A. Glucose has less free energy than CO 2 B. The oxidation of glucose into CO 2is endergonic. C. So few molecules gain the energy required to get to the transition state. D. Glucose break-down is a thermodynamically non-spontaneous reaction. 16.During glycolysis, the conversion of glucose to glucose-6-phosphate proceeds through an energy coupling process mediated by the enzyme hexokinase and ATP. Which of the following statements about this process is correct? A. Glucose-6-phosphate is more stable than glucose. B. The free energy of ATP is conserved by the transfer of a phosphate group. C. The addition of ATP makes the reaction occur faster. D. After ATP is hydrolyzed into ADP and orthophosphate (Pi), the Pi group is transferred to glucose. 17.What would you need to do in order to determine if a newly discovered protein is probably a membrane protein? A. Evaluate the primary sequence. B. Express the protein in a cell and visualize it using fluorescence microscopy. C. Expresstheprotein in vitro to determine ATP-binding activity. D. Use a computer algorithm to determine the likelihood of alpha helix formation. 18. Themik5/8 mutant of E. coli does not synthesize any functional desaturase enzymes. Interestingly, the mutant can grow at higher temperature than wild-type cells. How is this best explained? A. Mutant cells have membranes that remain fluid at all growth temperatures. B. Wild-type cells have membranes that are more rigid at higher temperatures. C. Wild-type cells contain some unsaturated fatty acids at high temperatures. D. Mutant cells have constitutively high abundance of unsaturated fatty acids. 19.Which of the following statements about enzyme kinetics is correct. A. TheK is the rate of the reaction at high substrate concentrations. m B. If an enzyme has a high V max then it must have a low K m C. It is common for the K m of an enzyme to equal the V max. D. In humans, enzymes known to break down toxins have a low K m. Student Number __________________________ Code 222 Code 222 Code 222 February 2011 Biology 1002B Page 4 of 7 20.Which of the following statements about membranes and membrane transport are correct? 1. CFTR pumps H 2 into the epithelial lining.
 2. NAD + moves by simple diffusion across the inner mitochondrial membrane. 3. A consequence of low ATP levels is inhibition of ABC transporter function. 4. Trans unsaturated fats are kinkier than cis unsaturated fats. 5. At high substrate concentrations the rate of facilitated diffusion of a molecule is similar to the rate of its simple diffusion. A. 3,5 B. 1,2,5 C. 2, 3, 4 D. 1, 2, 4 21.Which of the following diagrams most accurately reflects the actual abundance of CFTR transporters at the plasma membrane of a single epithelial cell of the given genotype? (C = wild type = thick line; c = ΔF508 mutation = thin line) A B C D Cc Cc Cc cc Plasma membrane 22.Why was the development of enzymes fundamental to the evolution of life? A. Enzymes allowed for all reactions to occur spontaneously. B. Without enzymes the energy of activation (E A)
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