Microbiology 2124
Exam 1
Sept. 15, 1999
David Demezas

General instructions: Answer multiple choice questions on your scan-tron sheet. Answer other questions in the space provided on this test sheet. Be sure that you answer the question in complete sentences. Write your name on all pages of the test.

Multiple choice (2.5 pts each) Chose the most correct answer and mark the corresponding letter on your scan-tron sheet.

1. ________ and _________ were instrumental in disproving the theory of spontaneous generation.
A. Pasteur and Koch
B. van Leeuwenhoek and Hooke
C. Pasteur and Redi
D. Redi and Koch
E. van Leeuwenhoek and Pasteur

2. In 1670’s, _______ first observed microorganisms ("wee animalcules") using a simple microscope.
A. Pasteur
B. Petri
C. Hooke
D. Redi
E. van Leeuwenhoek

3. _______ developed a smallpox vaccine from the contents of cowpox blisters.
A. Jenner
B. Fleming
C. Virchow
D. Hooke
E. Lister

4. The treatment of disease by using a chemical substance is called _______.
A. parasitology
B. mycology
C. pasteurization
D. chemotherapy
E. biogenesis

5. Which of the following is not a beneficial activity of microorganisms?
A. Some microorganisms are used as biocontrol agents of plant pests.
B. Some microorganisms are used directly as food.
C. Some microorganisms produce oxygen.
D. Some microorganisms provide a source of nitrogen for plant growth.
E. All of the above are beneficial activities of microorganisms.

6. True (A) or False (B): Bacteria have not evolved since they first appeared on earth some 3.5 billion years ago.

7. Which of the following types of microscopes is used in our Micro2124 laboratory?
A. Confocal microscope
B. Epifluorescent microscope
C. Dark field microscope
D. Phase contrast microscope
E. Bright field microscope

8. You are using a microscope to view a specimen. The eyepieces have a 10x magnification and the objectives have a 40x magnification. What is the final magnification of the specimen?
A. 40x
B. 4x
C. 10x
D. 400x
E. 4000x

9. Which of the following is the correct order of reagents used for the Gram stain?
A. crystal violet, iodine, alcohol, then safranin
B. safranin, iodine, crystal violet, then alcohol
C. crystal violet, alcohol, safranin, then iodine
D. safranin, alcohol, crystal violet, then iodine
E. crystal violet, safranin, alcohol, then iodine

10. True (A) or False (B): Electron microscopes have a much greater level of resolution than a light microscope.

11. Which of the following microscopes produces a bright image on a dark background?
A. Bright field microscope
B. Phase contrast microscope
C. Dark field microscope
D. Confocal microscope
E. None of the above.

12. Which of the following is in the correct ascending (increasing) order of size?
A. Na+, H2O, glucose, phospholipid, chromosome, cell
B. H2O, Na+, glucose, phospholipid, chromosome, cell
C. glucose, Na+, H20, chromosome, cell, phospholipid
D. H20, glucose, Na+, cell, chromosome, phospholipid
E. cell, chromosome, H20, Na+, phospholipid, glucose

13. True (A) or False (B): Acidic dyes (anionic) are used as simple stains to colorize cells of bacteria.

14. You are Gram staining an unknown mixture of bacteria. Your lab partner is joking around and you unconsciously skip flooding the slide with iodine. What color(s) do you predict the cells will be?
A. All purple
B. Mostly purple/ some red
C. No color
D. All red
E. All blue

15. You have isolated a new strain of bacteria with a single flagellum located on both ends of the cell. This strain is _________ flagellated.
A. monotrichous polar
B. amphitrichous
C. peritrichous
D. lophotrichous
E. trichomous

16. A bacterium swimming with long runs and infrequent tumbles towards a light source is _________.
A. chemotactic
B. attracted to oxygen
C. phototactic
D. magnetotactic
E. none of the above

17. Bacterial fimbriae may enhance virulence of bacterial pathogens by ______.
A. increasing their surface area
B. providing a means of attachment to host cells
C. being an endotoxin
D. transporting nutrients into the cell
E. none of the above

18. A rod shaped bacterium is called ________.
A. coccus
B. spirillum
C. bacillus
D. helix
E. spirochete

19. Which of the following statements about the cytoplasmic membrane is False?
A. It is composed of phospholipid bilayer.
B. Integral proteins span the membrane.
C. Protons (H+) can move across the membrane by simple diffusion.
D. The membrane is a fluid structure.
E. It has a hydrophobic core and hydrophilic layers on the outside

20. The outermost layer of Gram negative bacteria is called _________.
A. the cytoplasmic membrane
B. porin
C. teichoic acid
D. the lipopolysaccharide layer
E. the periplasmic space

21. The antibiotic penicillin inhibits the formation of the peptide bridge between neighboring N-acetyl muramic acid residues. As a result, the _________ is greatly weakened and the cell may rupture (lyse).
A. cytoplasmic membrane
B. nucleus
C. lipopolysaccharide layer
D. cell wall (peptidoglycan layer)
E. periplasm

22. Transport proteins that transport one substance across the cytoplasmic membrane in one direction and another substance across in the opposite direction are called _______.
A. uniporters
B. symporters
C. antiporters
D. importers
E. reporters

23. True (A) or False (B): Without ATP or the proton motive force, active transporters cannot carry out their function.

24. Which of the following statements about the bacterial chromosome is False?
A. It is usually circular.
B. It is hundreds of times longer than the bacterium.
C. It is usually supercoiled.
D. It is the only genetic material in all bacteria.
E. It must be replicated before a cell can divide.

25. True (A) or False (B): Catabolic reactions do not require energy to synthesize macromolecules (e.g., proteins).

26. Which of the following statements about enzymes is False?
A. Each enzyme carries out a specific reaction.
B. Enzymes lower the activation energy of reactions.
C. Enzymes are only used once and then discarded.
D. Enzymes are a class of proteins.
E. Enzyme activity is affected by both pH and substrate concentrations.

27. An enzyme converts 1000 molecules of substrate to product each second at 15 ^oC. What would you correctly predict the rate to be at 25 ^oC?
A. 500 molecules per second
B. 2000 molecules per second
C. 40 molecules per second
D. 4000 molecules per second
E. None of the above since the enzyme would be denatured at this temperature.

28. Which of the following are the oxidized forms of two very important coenzymes that carry protons and electrons?
A. NAD⁺ and FAD
B. Mg⁺² and Fe⁺³
C. NADH and FADH₂
D. CoA and FAD
E. CoA and acetyl CoA

29. You have been studying a specific enzyme in Dr. Narromine’s lab. He tells you that when he adds an inhibitory level of an inhibitor to the enzyme and increasing levels of substrate, the enzyme shows inhibition at the lower levels of substrate, but no inhibition at the higher levels of substrate. You conclude that this enzyme is _________ and Dr. Narromine wins the Nobel prize for biochemistry that year.
A. irreversibly competitively inhibited
B. noncompetitively inhibited
C. reversibly competitive inhibited
D. regulated at the transcriptional level
E. very unusual and should be destroyed immediately

30. Most biological oxidations ________.
A. require ATP
B. occur spontaneously
C. involve the gain of electrons
D. occur uncoupled to a reduction reaction
E. involve the loss of protons and electrons

31. The pathway that yields 2 pyruvates, some ATP and NADH + H⁺ is called ________.
A. Calvin cycle
B. Kreb’s cycle
C. gluconeogenesis
D. glycolysis
E. TCA cycle

32. True (A) or False (B): All species of bacteria have the glycolytic pathway and Kreb’s cycle.

33. A total of _______ ATPs are generated from aerobic respiration, while only _____ ATPs are generated from fermentation.
A. 38 / 2
B. 2 / 38
C. 38 / 4
D. 4 / 38
E. 4 / 4

34. True (A) or False (B): All carbon-based molecules that enter the Kreb’s cycle never exit and are oxidized to CO₂.

35. The electron transport chain is located in the _______.
A. cytoplasm of the cell
B. plasma membrane
C. peptidoglycan layer
D. periplasmic space
E. Golgi apparatus

36. Which of the following statements about the proton motive force is False?
A. It is an electrochemical potential.
B. It is generated as the electrons move down an electron transport chain and protons are pumped out of the cell.
C. The cytoplasm of the cell becomes more basic (alkaline) and the outside of the cell becomes more acidic.
D. It can be used to make ATP and drive the flagella.
E. All of the above statements are true.

37. Which of the following types of metabolism does not generate a proton motive force what can be used to make ATP?
A. Fermentation
B. Aerobic respiration
C. Anaerobic respiration
D. Phototrophy
E. all of the above do not generate a proton motive force.

38. Chemotrophy and phototrophy refer to ________.
A. differences in carbon sources
B. differences in oxygen requirements
C. differences in temperature optima for growth
D. differences in energy sources
E. none of the above

39. Phototrophic bacteria make ATP using ________.
A. cyclic photophosphorylation
B. oxidative phosphorylation
C. substrate level phosphorylation
D. non-cyclic photophosphorylation
E. two of the above

40. Chemolithotrophs ____________.
A. get their energy from the oxidation of reduced inorganic compounds (NH₄⁺) and carbon from CO2 fixation.
B. get their energy from the sun and carbon from organic compounds
C. get their energy form oxidation of oxidized compounds (e.g., NO₃^-) and carbon from organic compounds
D. get their energy from the sun and carbon from CO2 fixation
E. are synonymous with chemoheterotrophs.

41. List Koch’s postulates

42. Briefly explain how the electron transport chain of aerobic bacteria is linked to ATP synthesis. (A drawing may help, but you still need to explain the processes)