Test 1

23. You perform a ten-fold serial dilution of a culture to determine the number of colony forming units (CFU) per mL. You do a plate count with the growth results given below. The number of CFU per mL in the original culture was: a. 860,000 b. 10,000 c. 86 d. 860 e. Correct answer not given

a. 860,000

30. For the following DNA sequence (reading from left to right), what will be the mRNA sequence after transcription? DNA sequence: TACCATATAGGTATC a. AUGGUAUAUCCAUAG b. AUGCAUUUUGCGCGA c. ATGGTATATCCATAG d. AUGCCCGUGGAAUAG e. Correct answer not given

a. AUGGUAUAUCCAUAG

3. You observe a cell through a microscope and see that it has mitochondria. To which Domain of organisms does it belong? a. Eukarya b. Animals c. Archaea d. Bacteria e. Cannot be determined from the information provided

a. Eukarya

48. A major milestone in the history of microbiology was the development of the "germ theory of disease" in 19th century Europe. Which of the following is NOT a true statement about this theory? a. It confirmed the long-held belief that diseases arise from spiritual causes, miasmas, and/or vapors b. It arose partly from observations about bacterial contamination of fermentation processes in beer and wine c. It says that diseases of people and other animals can be caused by living organisms too small to be seen with the unaided eye d. It led to the development of infection control practices including aseptic surgery e. None of the above (All are true statements about the germ theory of disease)

a. It confirmed the long-held belief that diseases arise from spiritual causes, miasmas, and/or vapors

41. Which of the following is NOT a true statement about animal viruses? a. Mechanisms of replication are identical for all RNA animal viruses, regardless of whether the RNA is single- or double-stranded, sense (+) or antisense (-) b. The chromosomal DNA of every human cell contains the remnants of ancient retroviruses c. They can be grown in embryonated eggs, cell cultures, and whole living animals d. Some animal viruses lyse (rupture) cells and others are released from the cell by budding e. None of the above (All are true statements about animal viruses)

a. Mechanisms of replication are identical for all RNA animal viruses, regardless of whether the RNA is single- or double-stranded, sense (+) or antisense (-)

9. In the Gram stain, gram-positive bacteria are dark purple for all the following reasons EXCEPT: a. The counterstain (safranin) causes the purple color to develop b. Thick peptidoglycan in the gram-positive cell wall prevents decolorization by alcohol c. Crystal Violet is fixed inside the cell as a CV-iodine complex once iodine is added d. The primary stain, Crystal Violet, is dark purple e. None of the above (All are reasons that gram-positive bacteria are purple in the Gram stain)

a. The counterstain (safranin) causes the purple color to develop

34. Which of the following is NOT true of viruses? a. They are the smallest microorganisms composed of cells b. Most viruses have a narrow host range c. They are obligate intracellular parasites d. They have DNA or RNA but never both e. None of the above (all are true of viruses)

a. They are the smallest microorganisms composed of cells

16. In the diagram at right, enzyme action has been stopped (prevented) by binding of what to the active site? a. competitive inhibitor b. allosteric inhibitor c. noncompetitive inhibitor d. substrate e. none of the above

a. competitive inhibitor

21. Starting with a single bacterial cell at time zero, assuming binary fission every 30 minutes, how many cells will be present in a culture after 4 hours? a. 4 X 30 (120) b. 256 c. 512 d. 4 X 102 (400) e. None of the above

b. 256

26. In the figure at right, what is the Decimal Reduction Time for the organism? a. 1 minute b. 5 minutes c. 15 minutes d. 30 minutes e. Cannot be determined from graph

b. 5 minutes

37. Which of the following statements is NOT true about prophage and lysogeny? a. A prophage can sometimes exit from the bacterial chromosome and start a lytic cycle b. A prophage is excised (exits) from the chromosome each time the bacterial cell divides c. Lysogenic cells cannot be reinfected by the same type of phage d. A prophage is phage DNA inserted into the bacterial chromosome e. A prophage may result in new genetic properties of the host cell

b. A prophage is excised (exits) from the chromosome each time the bacterial cell divides

10. Which of the following is NOT true about chemoheterotrophs? a. Use organic compounds as a source of both carbon and energy b. Can use light for energy and CO2 as a source of carbon c. They are ultimately dependent on autotrophs to provide their carbon and energy d. Oxidize organic compounds (e.g., glucose) to generate ATP e. None of the above (All are true of chemoheterotrophs)

b. Can use light for energy and CO2 as a source of carbon

32. Bacterial conjugation can result in genetic recombination of the recipient cell because: a. Transposons move genes from one cell or chromosome to another cell b. Donor (Hfr or F+) cells transfer chromosomal and/or plasmid DNA to a recipient (F-) cell c. DNA fragments from dead donor cells in the environment are taken up by recipient cells d. Donor cell DNA is accidentally inserted into viral (bacteriophage) capsids e. None of the above

b. Donor (Hfr or F+) cells transfer chromosomal and/or plasmid DNA to a recipient (F-) cell

4. Which of the following is NOT true of ionic bonds? a. They are involved in forming the tertiary structure of proteins b. Electrons are shared by atoms c. They are stronger than hydrogen bonds d. They are weaker than covalent bonds e. None of the above (all of the above are true of ionic bonds)

b. Electrons are shared by atoms

45. Which of the following is NOT true about the evolution of life on earth? a. The first life on earth was simple organisms, probably similar to today's prokaryotes b. Eukaryotes appeared first and prokaryotes came from organelles that escaped and evolved c. Mitochondria and chloroplasts are in some ways similar to prokaryotes d. Eukaryotes probably evolved from symbiotic prokaryotes living inside other prokaryotes e. None of the above (All are true statements)

b. Eukaryotes appeared first and prokaryotes came from organelles that escaped and evolved

15. Bacteria that grow best (optimally) at very high temperatures are called: a. Mesophiles b. Hyperthermophiles c. Halophiles d. Capnophiles e. Psychrophiles

b. Hyperthermophiles

19. Which of the following is NOT a true statement about the diagram below right? a. Each enzyme is specific for its substrate b. The end-product serves as a competitive inhibitor of the initial substrate on enzyme 1 c. The diagram shows a metabolic pathway d. The product of each enzyme reaction becomes a substrate for the next enzyme e. None of the above (All are true statements)

b. The end-product serves as a competitive inhibitor of the initial substrate on enzyme 1

39. Which of the following is NOT true of prions? a. They are infectious protein without any DNA or RNA b. They are the smallest known type of virus c. They cause fatal diseases of the brain in humans and other animals d. They cause a change in normal cell proteins that is associated with disease e. None of the above (All are true of prions)

b. They are the smallest known type of virus

50. The diagram below illustrates or implies all of the following EXCEPT: a. The substrate AB is converted into the products A and B b. With enzyme, more energy is needed to make the reaction happen c. The products end up at a lower energy level than the initial substrate d. The reaction is more likely to happen with enzyme than without enzyme e. None of the above (all are illustrated by the diagram)

b. With enzyme, more energy is needed to make the reaction happen

12. In biological systems, anabolic and catabolic reactions are coupled by: a. Krebs cycle b. Glycolysis c. Adenosine Triphosphate (ATP) d. The Electron Transport Chain e. Photosynthesis

c. Adenosine Triphosphate (ATP)

35. During animal virus replication, the correct sequence of events is: a. Biosynthesis, uncoating, entry, maturation, attachment, release b. Release, maturation, attachment, biosynthesis, entry, uncoating c. Attachment, entry, uncoating, biosynthesis, maturation, release d. Attachment, entry, maturation, biosynthesis, uncoating, release e. None of the above

c. Attachment, entry, uncoating, biosynthesis, maturation, release

24. In the bacterial growth curve shown at right, the vertical axis shows logarithm of the number of bacteria and the horizontal axis shows time in hours. In which phase(s) does the rate of cell deaths equal the rate of cell divisions? a. A b. B c. C d. D e. A & D

c. C

1. Which of the following pairs is mismatched? a. Louis Pasteur - disproved spontaneous generation of microbes with a "goose-neck" flask b. Edward Jenner - developed the first smallpox vaccine using cowpox virus (vaccinia) c. Joseph Lister - discoverer of penicillin d. Barbara McClintock - discovered and described transposons e. None of the above are mismatched

c. Joseph Lister - discoverer of penicillin

17. This figure shows the typical growth pattern in culture for a(n): a. Facultative anaerobe b. Obligate aerobe c. Obligate anaerobe d. Microaerophile e. None of the above

c. Obligate anaerobe

22. Which of the following is mismatched? a. Sepsis: presence of significant microbial contamination b. Pasteurization: 72o C for 15 seconds to kill pathogenic (disease-causing) microbes c. Sanitization: total destruction of all forms of microbial life, including endospores d. Bacteriostasis: inhibiting, but not killing, microorganisms e. Disinfection: destruction of vegetative (non-endospore) pathogens

c. Sanitization: total destruction of all forms of microbial life, including endospores

42. A culture medium that suppresses the growth of unwanted microbes and encourages desired microbes is called a: a. Complex medium b. Reducing medium c. Selective medium d. Chemically defined medium e. Differential medium

c. Selective medium

46. The figure below shows the number of infectious bacteriophage particles detectable during a single lytic cycle of infection. Which of the following statements is NOT true about the figure? a. The cycle starts with attachment of a single phage particle at time zero b. Phage particles are not detectable during the "eclipse" period when biosynthesis and maturation occur c. The "burst size" is the number of bacterial cells necessary to support replication of the bacteriophage d. The rapid increase in the number of phage particles after the "burst time" results from the release of hundreds of phage from the ruptured bacterial cell e. None of the above (All are true statements about the figure)

c. The "burst size" is the number of bacterial cells necessary to support replication of the bacteriophage

7. If a bacterial cell is placed in a hypertonic (hyperosmotic) solution: a. Water moves through the plasma membrane into the cell b. There is no net movement of water either into or out of the cell c. Water moves through the plasma membrane out of the cell, causing plasmolysis d. The cell undergoes osmotic lysis e. None of the above describe what happens in a hypertonic solution

c. Water moves through the plasma membrane out of the cell, causing plasmolysis

29. Which of the following is NOT true of transfer RNA (tRNA)? a. tRNA carries the anticodons that pair with codons on mRNA b. Interacts with mRNA during translation on the ribosome c. tRNA molecules lack specificity for which amino acid they carry d. Carries amino acids for addition to the growing protein chain e. None of the above (all are true of tRNA)

c. tRNA molecules lack specificity for which amino acid they carry

2. From the information given below, what is the molecular weight of the amino acid glycine, C2H5NO2? a. 43 b. 40 c. 35 d. 75 e. Correct answer not given

d. 75

36. Which of the following is NOT true of PERSISTENT viral infections? a. Continuous, low-level viral shedding for months or years b. Disease process occurs gradually over long period c. Prolonged, ongoing slow replication of a virus over a long time d. A virus or its nucleic acid remains inactive (non-replicating) in the host for long periods e. None of the above (All are true of persistent viral infections)

d. A virus or its nucleic acid remains inactive (non-replicating) in the host for long periods

18. Regarding the equations below, which of the following statements is NOT true? O2-* + O2-* + 2H+ + superoxide dismutase > H2O2 (hydrogen peroxide) + O2 2H2O2 + catalase > 2H2O + O2 a. Strict (obligate) anaerobes cannot produce superoxide dismutase or catalase b. Both O2-* and H2O2 are toxic for bacteria c. Superoxide free radicals (O2-*) are formed in small amounts during normal bacterial respiration d. Aerobes don't need to produce superoxide dismutase or catalase because oxygen isn't toxic for them e. None of the above (All are true statements)

d. Aerobes don't need to produce superoxide dismutase or catalase because oxygen isn't toxic for them

43. Which of the following is NOT correctly matched? a. Halophile - microbe that can grow in an environment with high osmotic pressure b. Colony - a population of microbial cells arising from a single cell or spore or from a group of attached cells c. Agar - complex polysaccharide from seaweed used as a solidifying agent in culture media d. Capnophile - microbe requiring an elevated molecular oxygen (O2) environment for optimal growth e. None of the above (All are correctly matched)

d. Capnophile - microbe requiring an elevated molecular oxygen (O2) environment for optimal growth

8. All of the following are correctly matched and can be found in bacteria EXCEPT: a. Flagella - rotate to cause "tumble and run" motility b. Cell wall - contains peptidoglycan c. Cell (plasma) membrane - encloses cytoplasm; phospholipid bilayer with proteins d. Chloroplasts - membrane-bound organelles where photosynthesis takes place e. None of the above (all are correctly matched and can be found in bacteria)

d. Chloroplasts - membrane-bound organelles where photosynthesis takes place

31. For the mRNA sequence (question #30), what will be the amino acid sequence following translation? (Use chart at right) a. Met-His-Phe-Ala-Arg b. Pro-Val-Met-Leu-His c. Met-Pro-Val-Glu d. Met-Val-Tyr-Pro e. None of the above

d. Met-Val-Tyr-Pro

5. Which of the following statements is NOT true of biological organic molecules? a. Usually polymers formed from subunits (monomers) b. Their atoms are mostly or entirely covalently bonded c. Always contain hydrogen and carbon d. Monomers are linked (bonded) together by hydrolysis ("water splitting") e. None of the above (i.e., all of the above are true)

d. Monomers are linked (bonded) together by hydrolysis ("water splitting")

28. Which of the following is NOT true about mutations? a. Nucleotide insertion or deletion in DNA can cause frameshift mutations b. Nucleotide substitution in DNA can cause nonsense mutations c. Mutagens increase the rate of mutation, but mutations are still random d. Mutations can be harmful but not beneficial e. Nucleotide substitution in DNA can cause missense mutations

d. Mutations can be harmful but not beneficial

13. In the diagram below, which of the following is TRUE? a. The NAD+ becomes oxidized b. The organic molecule becomes reduced c. Neither molecule is oxidized or reduced d. The NAD+ becomes reduced e. None of the above are true

d. The NAD+ becomes reduced

47. Which of the following is NOT true about bacterial endospores? a. They are "resting cells" for survival during adverse environmental conditions b. Resistant to desiccation (drying), heat, and chemicals c. Formed by walling off one end of the bacterial cell and surrounding it with a thick spore coat d. They represent a type of reproduction because there an increase in the number of bacterial cells e. They are produced by bacteria of the genus Bacillus and Clostridium

d. They represent a type of reproduction because there an increase in the number of bacterial cells

38. When lysogenic prophage start a lytic cycle, carrying adjacent genes from the bacterial chromosome, then infect a second bacterial cell, causing genetic recombination involving these adjacent genes, this is called: a. Transfection b. Transformation c. Generalized transduction d. Transcription e. None of the above

e. None of the above

27. Genetic information can be transferred horizontally from one bacterial cell to another cell of the same generation (versus daughter cells), leading to genetic recombination, by all of the following mechanisms EXCEPT: a. Conjugation b. Transduction c. Transformation d. Plasmids e. None of the above (All are mechanisms of "horizontal transfer" genetic recombination)

e. None of the above (All are mechanisms of "horizontal transfer" genetic recombination)

14. The complete aerobic respiration of glucose yields far more energy than glycolysis alone for all of the following reasons EXCEPT: a. Glycolysis only partially oxidizes the glucose molecule to pyruvic acid b. Krebs cycle generates additional ATP through substrate-level phosphorylation c. Electron transport chain (terminal respiratory pathway) produces many ATPs through oxidative phosphorylation using electron carrier molecules (NADH and FADH2) d. Krebs cycle generates reduced electron carrier molecules (NADH and FADH2) e. None of the above (All are reasons that aerobic respiration yields more energy)

e. None of the above (All are reasons that aerobic respiration yields more energy)

44. You perform an experiment, in which you inoculate bacteria into a medium that contains glucose and lactose (a disaccharide composed of two monosaccharides, glucose and galactose) as a sole source of carbon and energy, then monitor the number of cells over time, with the results shown in the figure below. All of the following are correct observations about the results EXCEPT: a. The lag time shows that inducible enzymes had to be produced before lactose metabolism could proceed b. The bacteria preferentially metabolized glucose before starting to metabolize lactose c. The number of cells increased at a more rapid rate when glucose was utilized rather than lactose d. The bacteria could use either glucose or lactose as a source of carbon and energy. e. None of the above (All are true)

e. None of the above (All are true)

33. For the mode of action of disinfectants, which of the following is mismatched? a. Halogens (Iodine & Chlorine) - strong oxidizing agents b. Phenols - disrupt plasma membranes, denature enzymes c. Cationic detergents (quaternary ammonium compounds) - enzyme inhibition, membrane disruption d. Alcohols - protein denaturation, dissolve lipid membranes e. None of the above (all are matched correctly)

e. None of the above (all are matched correctly)

11. Which of the following is NOT true of photosynthesis? a. Light-excited electrons in chlorophyll provide the energy for ATP production b. The light-dependent reaction captures electrons in NADPH, which are used to transfer energy for ATP formation in a series of oxidation-reduction reactions c. The light-dependent reaction converts light energy to chemical energy stored in ATP d. The light-independent ("dark") reaction makes glucose from carbon dioxide (CO2) and water, using energy trapped by the light-dependent reaction e. None of the above (all are true of photosynthesis)

e. None of the above (all are true of photosynthesis)

40. Which of the following is NOT true of retroviruses? a. Include Human Immunodeficiency Virus (HIV-1) b. Can integrate into host cell chromosome as a double stranded DNA provirus c. Can produce DNA from an RNA template using reverse transcriptase enzyme d. Provirus may reside for a long period of time inside a host cell chromosome e. None of the above (all are true of retroviruses)

e. None of the above (all are true of retroviruses)

6. Which of the following statements is NOT true? a. Decomposition (degradation, catabolic) reactions are usually exergonic b. Enzymes increase the probability that a chemical reaction will take place by lowering the activation energy c. The activation energy is the energy required to cause a chemical reaction to occur d. Synthesis (anabolic) reactions are usually endergonic e. None of the above (all of these statements are true)

e. None of the above (all of these statements are true)

20. Without using oxygen, some microorganisms can convert pyruvic acid to a variety of end-products such as ethyl alcohol, lactic acid, acetic acid, and butyric acid. This process is called: a. Krebs cycle b. Phosphorylation c. Respiration d. Photosynthesis e. None of the above are the name of this process

e. None of the above are the name of this process

49. Which of the following is NOT a true statement? a. The first chemotherapy against bacterial infection arose from Paul Erlich's concept of a "magic bullet" and his development of the arsenic-containing drug "salvarsan" for syphilis b. Antibiotics are naturally occurring antibacterial molecules produced by fungi or bacteria c. Alexander Fleming discovered penicillin by accident when he observed mold (Penicillium) contaminants inhibiting bacterial growth on petri dishes d. Rene Dubos discovered additional antibiotics produced by a soil bacterium (Bacillus brevis) e. The most effective antibiotics are those with a low differential (selective) toxicity between bacteria and humans

e. The most effective antibiotics are those with a low differential (selective) toxicity between bacteria and humans

25. The phenotype of an organism is best defined as: a. a type of point mutation b. the total of all hereditary information in the organism's DNA c. a subunit of DNA composed of a nitrogenous base, a pentose sugar, and a phosphate d. a segment of DNA that codes for a functional product e. actual, expressed physical and biochemical properties of the organism

e. actual, expressed physical and biochemical properties of the organism