Microbiology 2124
Exam 1
Feb. 9, 1999
David Demezas

General Instructions: Answer multiple choice questions on the test sheet. Answer other questions in the space provided on the 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 the blank provided to the left of the question.

D 1. The criteria used to relate a specific microbe to a specific infectious disease (the germ theory of disease) were established by ________ in the last century.
A. Pasteur
B. Petri
C. Hooke
D. Koch
E. Leeuwenhoek

E 2. Which of the following is used routinely to solidify liquid medium used for bacterial growth?
A. gelatin
B. jelly
C. starch
D. yeast
E. agar

D 3. Which of the following domains do not have a membrane bound nucleus?
A. Archaea
B. Bacteria
C. Eukarya
D. Both A and B
E. Both B and C

B 4. Which of the following statements about cells is false?
A. They are self-feeding and replicating.
B. They are in chemical equilibrium with their surrounding.
C. They interact with other cells by chemical signaling.
D. They undergo differentiation as part of their normal life cycle.
E. They evolve with time.

A 5. The coding function of a cell includes the following: (i) DNA is ________ before a cell divides, (ii) DNA is __________ into RNA and (iii) messenger RNA (mRNA) is _________ into a polypeptide.
A. replicated / transcribed / translated
B. transcribed / replicated / translated
C. replicated / translated / transcribed
D. translated / transcribed / replicated
E. translated / replicated / transcribed

A 6. True (A) or False (B). The diversity of microorganisms in nature is due to evolution by natural selection.

C 7. _______ performed the famous "swan-necked flask" experiment to disprove spontaneous generation.
A. Antoni van Leeuwenhoek
B. Robert Hooke
C. Louis Pasteur
D. Robert Koch
E. Walter Hesse

A 8. Which of the following microscopes do you use routinely in Micro 2124's laboratory?
A. Bright field microscope
B. Phase contrast microscope
C. Dark field microscope
D. Fluorescent microscope
E. electron microscope

B 9. A bacterium with a spherical morphology is called a ________.
A. spirilla
B. coccus
C. bacillus
D. rod
E. helix

B 10. True (A) or False (B). All bacteria are smaller than 2 microns in size.

C 11. Which of the following is not a feature of the plasma membrane?
A. It is composed of phospholipids arranged in a lipid bilayer.
B. Integral proteins are embedded in the plasma membrane.
C. The peptidoglycan layer is an integral part of the plasma membrane.
D. It is selectively permeable.
E. It is a fluid structure.

E 12. The peptidoglycan layer is composed of __________.
A. phospholipids
B. amino acids only
C. nucleotides
D. glucose and fructose
E. N-acetyl glucosamine, N-acetyl muramic acid and amino acids

C 13. You have isolated a bacterium with a single flagella attached to one end of the cell. What type of flagella is this?
A. lophotrichous flagella
B. peritrichous flagella
C. polar flagella
D. a pili
E. a fimbria

B 14. The rigidity and shape of a bacterium is due to the _______.
A. cell membrane
B. peptidoglycan layer
C. lipopolysaccharide
D. teichoic acid layer
E. none of the above

D 15. A bacterium swimming towards a chemoattractant experiences _________.
A. frequent tumbling and short runs
B. frequent tumbling and long runs
C. infrequent tumbling and short runs
D. infrequent tumbling and long runs
E. none of the above.

D 16. The outermost layer of a Gram negative bacterium is called the _______.
A. plasma membrane
B. porin
C. teichoic acid layer
D. lipopolysaccharide layer
E. murein layer

D 17. Which of the following is not a general feature of active transport?
A. Requires a carrier protein
B. Requires a form of energy
C. Can move molecules against a concentration gradient
D. All of the above are characteristic of active transport

B 18. A number of species of bacteria produce _________ in response to extreme changes in the environment, e.g., moist to extremely dry conditions.
A. porins
B. endopsores
C. lysozyme
D. peptidoglycan
E. LPS

C 19. Which of the following elements makes up the greatest percentage of a cell's dry weight?
A. Nitrogen
B. Phosphorous
C. Carbon
D. Iron
E. Calcium

A 20. Which of the following coupled reactions is correct? Use the attached table for redox potentials.
A. H₂ -----> 2H⁺ + 2e^-
NO₃^- + 2e^- + 2H⁺ ----->NO₂^- + H₂O
--------------------------------------
H₂ + NO₃^- -----> NO₂^- + H₂O

B. NO₂^- + H₂O -----> NO₃^- + 2e^- + 2H⁺
2H⁺ + 2e^- -----> H₂
--------------------------------------
NO₂^- + H₂O ^- -----> H₂ + NO₃
C. Neither of them are correct.

B 21. The pathway that yields pyruvate from glucose is called ________.
A. Krebs cycle
B. glycolysis
C. gluconeogenesis
D. Tricarboxylic acid cycle
E. Calvin cycle

A 22. True (A) or False (B). Adenosine triphosphate and acetyl-CoA are both high energy compounds that may be coupled to and drive endergonic reactions.

A 23. Fermentation of glucose results in a net ______ ATP molecules whereas aerobic respiration beginning with glucose generates _____ ATPs.
A. 2 / 38
B. 38 / 4
C. 4 / 38
D. 2 / 2
E. 38 / 38

C 24. The majority of ATP generated during aerobic respiration results directly from ______.
A. substrate level phosphorylation
B. oxidation of NADH + H⁺
C. oxidative phosphorylation
D. the TCA cycle (syn. Krebs or citric acid cycle)
E. the electron transport chain

E 25. The proton motive force may be used to ___________.
A. drive the flagella
B. generate ATP
C. transport molecules across the cytoplasmic membrane
D. reverse electron flow to generate NADPH
E. all of the above

C 26. Who first proposed that the proton motive force could be used to drive ATP synthesis?
A. Peter Gabriel
B. Antoni van Leeuwenhoek
C. Peter Mitchell
D. Walter Hesse
E. Robert Hooke

E 27. The electron transport chain is located in the ________.
A. cytoplasm of the cell
B. peptidoglycan layer
C. lipopolysaccharide layer
D. periplasmic space
E. plasma membrane

C 28. Metabolism is defined as _______.
A. only catabolic reactions
B. only anabolic reactions
C. the sum of catabolic and anabolic reactions
D. None of the above.

C 29. Which of the following statements about the proton motive force is false?
A. It is composed of a pH gradient and electrochemical potential.
B. The proton motive force is generated as electrons move down an electron transport chain and protons are extruded out of the cell.
C. The cytoplasm of the cell becomes more acidic and the outside of the membrane more alkaline.
D. The proton motive force can be used to drive ATP synthesis using ATP synthase.
E. All of the above statements are true.

B 30. True (A) or False (B). In an aerobic respiring bacteria, all of the carbon in every glucose molecule of a growth medium is oxidized via glycolysis and the TCA cycle to carbon dioxide.

T 31. T or F Anoxygenic phototrophs do not produce oxygen gas during photosynthesis.

D 32. Phototrophic bacteria, e.g., purple bacteria, use ________ to make ATP.
A. oxidative phosphorylation
B. substrate level phosphorylation
C. non-cyclic photophosphorylation
D. cyclic photophosphorylation
E. none of the above

A 33. A common enzyme for the fixation of carbon dioxide in phototrophs and chemolithotrophs is _______.
A. ribulose bisphosphate carboxylase (Rubisco)
B. hydrogenase
C. ammonia monooxygenase
D. cytochrome bc1
E. ATP synthase

D 34. The passing of electrons down an electron transport chain generates a proton motive force yielding ATP in all of the following except ________.
A. aerobic respiring bacteria
B. chemolithotrophs
C. phototrophs
D. fermentative bacteria
E. all of the above

A 35. True (A) or False (B). NADPH can be generated using the energy of the proton motive force to reverse the natural flow of electrons in the electron transport chain.

A 36 Which of the following statements about facultative aerobes is correct?
A. Facultative aerobes can grow in the presence of a suitable electron acceptor, e.g., nitrate, in an anaerobic environment.
B. Facultative aerobes are extremely sensitive to even the smallest amounts of oxygen.
C. Facultative aerobes require oxygen for growth.
D. Facultative aerobes use only substrate level phosphorylation to make ATP.
E. Facultative aerobes are strictly fermentative organisms.
Match the following terms on the left with the correct definition on the right.

Short answer (5 pts each)
41. Compare the outer structures (everything outside the plasma membrane) of a Gram positive and Gram negative bacteria. You may wish to draw the two but be sure that you identify all of the important structures and note any differences between the Gram positive and negative bacteria.
SEE FIGURE 36 IN YOUR TEXT (P. 71)

42. Escherichia coli is a facultative aerobe that can use oxygen as a terminal electron acceptor in aerobic environments and nitrate (NO₃^- ) as a terminal electron acceptor in anaerobic environments. Which growth condition would provide the greatest yield of cells (i.e., the highest population density) with a given amount of glucose and why? (hint: The redox potentials are - 430 mVolts for CO₂ / glucose, + 820 mVolts for O₂ / H₂O and +430 mVolts for NO₃^- / NO₂ ^- )
Growth of the bacteria in an aerobic environment with oxygen as the terminal electron acceptor will yield the greatest population density because there is more energy for growth from the oxidation of glucose with oxygen as the terminal electron acceptor than the oxidation of glucose with nitrate as the terminal electron acceptor. Delta E_o´ for the aerobically grown bacteria is 820 -(-)430 mVolts = 1.250 Volts while delta E_o´ for the aerobically grown bacteria is 430 -(-)430 mVolts = 0.860 Volts. Delta G^o´, the energy for growth is proportional to Delta E_o´.