C) Viruses on the surface of the skin.
D) Bacteria in the intestines of human beings.
E) The fungus that causes infections under people's toenails.
A scientist isolates a microbe from a contaminated water source. She thinks that the organism might be a new bacteria that is capable of surviving in the presence of lead, a heavy metal. She makes tubes of growth medium containing either no lead, 0.1 mg lead, 0.25 mg lead, 0.5 mg of lead or 1 mg of lead. She inoculates each tube with the 10 × 103 cells of the new organism and then incubates the inoculated medium at 37oC. After 48 hours, she examines the tubes of medium and finds that there is no growth in any of them. However, she finds that the bacteria grew fine in medium that did not contain any lead. She decides to repeat the experiment using lower concentrations of lead than those she used initially.
67) Select which of the following is the hypothesis being tested by the scientist.
A) The newly isolated microbe can grow in the presence of lead.
B) The newly isolated microbe is a bacteria.
C) Lead can be placed into tubes of growth medium.
D) Bacteria must be incubated for 72 hours before they grow.
E) Lead is a good nutrient for all bacterial growth.
68) Identify the control step in the scenario described.
A) Inoculating the test microbe into nutrient medium containing lead.
B) Isolating the microbe from a contaminated water source.
C) Inoculating the test microbe into nutrient medium lacking lead.
D) Inoculating the test microbe into medium containing lower levels of lead than used initially.
E) Inoculating the test microbe into contaminated water containing high levels of lead.
69) What conclusion can the scientist in this scenario make from her results?
A) The test bacteria take more than 48 hours to grow in the laboratory when incubated at 37oC.
B) All contaminated water contains high levels of lead and other heavy metals.
C) The amounts of lead used in the experiment killed the bacteria being tested.
D) All experiments should be repeated three times or more.
E) Lead-contaminated water does not contain any bacteria at all.
70) Select the TRUE statement regarding viruses.
A) Most viruses are smaller than bacteria but bigger than mitochondria.
B) Viruses may be unicellular or multicellular.
C) Viruses have completely random shapes.
D) Viruses always cause death of the host cells they infect.
E) Virus are considered living because they contain nucleic acid.
Janus is a keen baseball player at the high school where you are employed as a nurse. He comes to your office and shows you an injury to his knee which he got by sliding into home base, scoring a game-winning run. His knee has a red, raw patch where the skin has been scraped off, and the area around the wound is swollen. Janus tells you that he washed his knee with soap and water to remove any germs and then put a bandage on it.
71) You explain to Janus that he may have an infection in his wound, possibly caused by the organism Staphylococcus epidermidis. You tell him that the genus name of the organism indicates that
A) the cells are found on the skin.
B) the cells are round and grow in clusters.
C) the organism is a pathogen.
D) the organism is normal microbiota.
E) the cells have a golden color.
72) Janus tells you he knows that yeast cells are also small and round. He asks how scientists can tell the difference between yeasts and bacteria. Select the choice that best answers his question.
A) Bacteria are microscopic.
B) Bacteria are photosynthetic.
C) Bacteria are unicellular.
D) Bacteria contain peptidoglycan.
E) Bacteria can be pathogenic.
73) Janus asks you if there is something he can use to kill any bacteria in his wound without affecting any of his own body cells. You tell him that some antibiotics kill bacteria by targeting ________, a compound unique to bacteria.
A) protein
B) nuclear membrane
C) flagella
D) peptidoglycan
E) chitin
74) Janus' knee infection should be considered an emerging infectious disease, and you should report it to the Centers of disease Control (CDC).
Sandy has been taking an antibiotic for a urinary tract infection (UTI). Although the signs and symptoms of Sandy's UTI resolved after a few days of taking the medication, she complains to you that she has been having watery diarrhea for the last two days, and she wonders whether the antibiotic is affecting her digestive tract. You take the opportunity to give her information about her normal microbiota.
75) You explain to Sandy that her body carries an enormous population of microorganisms, collectively called the normal microbiota. You tell her that this population has a vital role in maintaining her health. Select the FALSE statement regarding the role of the normal microbiota.