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        Midterm Exam—60 pts

        Multiple Choice—2 pts each

   1. Some helpful activities of bacteria include:
         a. Digesting food in our gut
         b. Breaking down organic material in the environment
         c. Creating biofilms on surgical implants
         d. A and B
         e. A and C

   2. Which of the following is true:
         a. Archaea are often pathogens
         b. Archaea are often extremophiles
         c. Archaea contain a nucleus
         d. Archaea are a family of bacteria
         e. None of the above

   3.    You are observing a wet mount of a flagellated bacteria under a microscope. After you add a
        particular chemical to the edge of the slide, you notice the bacteria have longer “runs” towards
        this chemical. This is an example of:
             a. Osmosis
             b. Symport
             c. Chemotaxis
             d. Quorum sensing
             e. Magnetotaxis

   4. Why is it important that the cellular membrane is selectively permeable?
        a. To allow the cell to concentrate nutrients inside
        b. To allow the proton pumps to function
        c. To allow passive diffusion to occur
        d. A and B
        e. A and C

   5. Which of the following transport processes does NOT require an energy source:
         a. Diffusion
         b. Symport
         c. Antiport
         d. Active transport
         e. Proton pump
6. People with cystic fibrosis are vulnerable to infection with the biofilm-forming bacteria
   Pseudomonas aeruginosa. Why is the formation of a biofilm of particular concern?
      a. Bacteria in biofilms do not attach to surfaces well, allowing them to spread more
          effectively throughout the body
      b. Biofilms are more resistant to antibiotics, thus harder to treat
      c. These bacteria make less EPS, so are protected from phagocytosis by immune cells
      d. Formation of a biofilm increases cell motility, allowing the cells to evade the immune
          system
      e. Formation of a biofilm increases the size of the cell wall, protecting the cells from
          antibiotics

7. You are interested in studying flagellated intestinal bacteria, which are usually Gram negative
   rods. However, you accidently contaminated your bacterial sample with some of your natural
   skin flora. Which media would you use to try and enrich your culture for your intestinal Gram
   negative rod bacteria?
       a. Eosin methylene blue (EMB) agar
       b. Trypticase soy agar
       c. Mannitol Salt agar
       d. Glucose Mineral agar
       e. Blood agar

8. You learn that an immunocompromised patient has become ill after eating contaminated deli
   meat, however the meat had been carefully stored at 4 °C in a fridge. What of the following is
   most likely causing this illness?
      a. Salmonella typhimurium
      b. Salmonella enteriditis
      c. Escherichia coli
      d. Listeria monocytogenes
      e. Vibrio parahaemolyticus

9. Which of the following is NOT a current concern when treating Mycoplasma tuberculosis
   infections?
       a. Selecting the correct antibiotic because M. tuberculosis can be highly drug resistant
       b. Making sure the patient takes their full course of antibiotics, which can last months
       c. Using combination therapy (multiple antibiotics) to prevent new resistance from
           emerging
       d. Treating the watery diarrhea associated with infection
       e. Determining whether granulomas have formed in the lungs
10. What is ATP?
      a. An electron carrier/donor made in the TCA cycle
      b. The end product of glycolysis that then is modified and enters the TCA cycle
      c. A result of the Calvin cycle
      d. The energy source for the proton pump in the electron transport chain
      e. A form of chemically stored energy for the cell to use

11. Which of the following is NOT true about photosynthesis?
       a. Photosynthesis requires light (photons)
       b. Excited electrons are generated from the splitting of water molecules
       c. Excited electrons are directly used to fix carbon
       d. Excited electrons are directly used to power the proton pumps
       e. Excited electrons are directly used to create NADPH

12. Which of the following statements about mRNA is FALSE:
       a. The level of mRNA in a cell are generally proportional to the level of the protein for
           which it codes
       b. mRNA transcription starts at the promoter site
       c. The amount of a given mRNA can be varied by the cell by regulating transcriptional
           repressors and activators
       d. There can be many mRNA molecules generated from one gene in the DNA
       e. mRNA is inherently stable in the cell

13. The role of tRNA in the cell is:
        a. To bring the correct amino acid to the growing polypeptide chain (the protein)
        b. As an integral component of the 70S ribosome
        c. To catalyze the addition of the amino acid to the growing polypeptide chain
        d. A and C
        e. B and C

14. You need to sterilize a liquid that is very heat-sensitive (heat will destroy it) and that contains
    bacterial endospores. What is the best method to use to sterilize this material?
        a. Treat for 30s with UV light
        b. Filtration
        c. Autoclaving
        d. Add quaternary ammonium compounds
        e. Pasteurization
15. Which of the following statements about nosocomial infections is FALSE:
       a. The bacteria that cause these types of infections are often non-pathogenic
       b. Resistance to antibiotics is a common trait
       c. Horizontal gene transfer to other antibiotic resistant bacteria is a problem
       d. These bacteria are only found in hospitals
       e. Acinetobacter baumanii forms biofilms

16. A mutant strain of E. coli has evolved the ability to use citrate as a carbon source, but it grows
    more slowly than the wild type bacteria when growing on glucose. When growing in conditions
    of high citrate and low glucose, this mutation would be__________________. When growing in
    conditions of low citrate and high glucose, this mutation would be_______________________.
        a. Advantageous; Disadvantageous
        b. Disadvantageous; Advantageous
        c. Advantageous; Neutral
        d. Neutral; Advantageous
        e. Neutral; Disadvantageous

17. Ethidium bromide is an intercalating agent. It can cause serious damage to DNA if it intercalates
    into a gene. Why is this?
        a. Because it can lead to base substitution, which always changes the amino acid
             transcribed
        b. Because it can lead to base substitution, which causes a frame-shift
        c. Because it can lead to a deletion event, which always changes the amino acid
             transcribed
        d. Because it can lead to a deletion event, which causes a frame-shift
        e. Because it can lead to spontaneous mutation, which causes a frame-shift

18. Which of the following is NOT true about mismatch repair:
       a. Enzymes are recruited to the site of the mismatch
       b. The DNA is repaired by using the template strand
       c. The newly synthesized strand is identified by the presence of methyl groups
       d. The mistake in the newly synthesized strand is degraded and repaired
       e. None of the above

19. Transduction is the process by which:
        a. RNA becomes a protein
        b. Phage inject a fragment of bacterial DNA into a bacteria
        c. Bacterial cells pick up naked DNA from the environment
        d. Plasmids pass between cells
        e. DNA becomes RNA
20. You have run tests to determine the exact bacteria causing an infection, which is E. coli
    O157:H7. The best oral antibiotic to prescribe is ____________________:
       a. A broad range antibiotic
       b. A narrow range antibiotic
       c. Pencillin
       d. Vancomycin
       e. Polymyxin B

21. Fluoroquinolones are __________________. They affect __________________.
        a. Bacteriostatic; DNA synthesis
        b. Bactericidal; DNA synthesis
        c. Bacteriostatic; RNA transcription
        d. Bactericidal: RNA transcription
        e. Bactericidal; Translation

22. You have found a strain of bacteria that is resistant to cephalosporins. Which of the following is
    a possible mechanism(s) by which this may have occurred?
        a. Production of a B-lactamase
        b. Mutation of transpeptidase (PBP)
        c. Mutation of the 50S ribosomal subunit
        d. A and B
        e. A and C

23. Which of the following is NOT true about plasmids:
       a. They do not contain an origin of replication and must be integrated into the
           chromosome in order to become permanent
       b. They can carry antibiotic resistance genes
       c. They can integrate into the chromosome
       d. They can be passed via conjugation between different species and even into plants
       e. They can accidently pick up chromosomal DNA
                                         C
                          A
                                  B

                                              E
                              D



    24.

    2 points: Based on the above image, please rank the susceptibility of the bacteria on the plate to
    each antibiotic A-E.




    25. 2 points: You are given a surgical mesh (fabric-like material) that is sensitive to liquids, UV light
        and heat. Name one method you could use to sterilize this mesh.




    26. 4 points: Please match, by drawing a line from the term to the matching role, the following
        terms with their role in the lac operon:

TERM:                                                                       ROLE:

Unphosphorylated transporter molecule R                                     Signals low glucose



Phosphorylated transporter molecule R-p                                     Inducer that binds repressor



cAMP                                                                        Blocks lactose transporter



Allolactose                                                                 Inducer that binds activator
    27. 6 pts You have isolated a completely new and unusual bacteria which has a cell wall made
        entirely of cellulose. The bacteria also lacks proton pumps and produces lactic acid as a by-
        product of metabolism. Finally, this bacteria was found to be quite resistant to UV light.

        Part A: Please explain, briefly, why penicillin would be ineffectual in treating this bacteria.




        Part B: Please explain what kind of metabolism this bacteria likely has.




        Part C: What is one reason this bacteria might be resistant to UV light?




Bonus question, 1 pt: Answer ONLY ONE (if you answer both, I will just grade the first one)

In class, we observed glowing Photobacteria on a plate. The production of bioluminescent molecules
(that make them light up) is controlled by what process (i.e. in what situation do these bacteria make
bioluminescent molecules)?




OR: Give one reason why plague is a candidate for a biological weapon.

				
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