Choose the BEST answer for each question and click on the button (circle) in front of that answer. If you answer ALL the questions, you can see your score when you are finished, as well as the correct answers.

1. The image here shows four different genera of bacteria growing in nitrate broths (tube 1 is a pure culture of one genus, tube 2 a pure culture of another genus etc.). After incubation alpha-napthylamine and sulfanilic acid were added to all four tubes. When no color change occurred in tubes 3 and 4, zinc dust was added to those tubes only. Based on these results (see image), which tubes would be recorded as a positive nitrate reduction test?

	Tubes 2 and 4 Tubes 2 and 3 Until zinc dust is added to tube 1, it cannot be determined whether it is positive or negative for nitrate reduction. Both b and c are correct. None of the above interpretations are correct.

2. Observe the results in the image shown for question 1. What is the correct conclusion?

1. The bacteria in tube 1 reduced nitrate to nitrite; the results are due to the presence of nitrite in the tube.
2. The bacteria in tube 2 reduced nitrate to nitrite; the results are due to the presence of nitrite in the tube.
3. The bacteria in tube 4 reduced nitrate to nitrite; the results are due to the presence of nitrite in the tube.
4. a and b are correct
5. b and c are correct

3. The image here presents the results of the urease test for two different bacteria. The organism that produced the result at the arrow is lactose negative and produces hydrogen sulfide on KIA media. This organism probably

	produces urease and is Salmonella. produces urease and is Shigella. doesn't produce urease and is Escherichia coli. produces urease and is Proteus. doesn't produce urease and is Staphylococcus aureus.

4. This image shows two different organisms growing on blood agar. If the two disks with "O" on them contain optochin, what conclusion can be drawn about the organism at the arrow?

	The organism is not Streptococcus pneumoniae. The organism is Streptococcus pneumoniae. The organism is not Streptococcus pyogenes. The organism is Streptococcus pyogenes. The organism is Staphylococcus aureus.

5. A pure culture of bacteria was inoculated into the broth culture in tube 1. A pure culture of another genus of bacteria was inoculated into tube 2. After incubation, both genera of bacteria produced equally turbid (cloudy) cultures. Desoxycholate (bile) was added to both tubes and the results are shown in the image. Which conclusion is correct?

	Tube 1 is Streptococcus pyogenes but tube 2 is not. Tube 2 is Streptococcus pyogenes but tube 1 is not. Tube 1 is Streptococcus pneumoniae but tube 2 is not. Tube 2 is Streptococcus pneumoniae but tube 1 is not. None of the above is correct.

6. Test results for four different genera of bacteria on KIA media are shown here. The bacteria that produced the result in Tube 3

	ferment glucose only. ferment lactose only. ferment both glucose and lactose. ferment glucose only and produce hydrogen sulfide. ferment glucose only and produce a gas other than hydrogen sulfide.

7. This image shows the test results for two different bacteria. The organism in box 2 is

	oxidase positive and could be Neisseria gonorrhoeae oxidase negative and could be Neisseria gonorrhoeae coagulase positive and could be Staphylococcus aureus coagulase negative and could be Staphylococcus aureus catalase positive and could be Staphylococcus aureus

8. This image shows the results of four different genera of bacteria inoculated into thioglycollate media and incubated for 24 hours. Growth occurred for each tube between the blue arrows. Which of the following is the correct conclusion?

	Obligate anaerobes are in tube 4. Obligate anaerobes are in tube 3. Obligate anaerobes are in tube 2. Obligate anaerobes are in tube 1. Obligate anaerobes are not in any of the tubes shown.

9. The primary function of the equipment shown in this image is to _____ for the cultures inside the jar.

	increase the concentration of oxygen decrease the concentration of oxygen eliminate oxygen increase the concentration of nitrogen decrease the concentration of nitrogen

10. The primary function of the equipment shown in this image is to _____ for the cultures inside the jar.

	increase the concentration of oxygen decrease the concentration of oxygen eliminate oxygen increase the concentration of nitrogen decrease the concentration of nitrogen