You wish to view a live bacterial cell that contains no natural pigments or fluorophores.  Which one of the following would be the most appropriate microscope for this task?

A.    A bright field microscope

B.    A phase contrast microscope  

C.    A fluorescent microscope

D.    An oil immersion microscope

(i)  Which response (A-D) is the best choice? (1 mark)

(ii ) Briefly explain your reasoning for your choice (2 marks)

Early investigators conducted experiments to seemingly demonstrate the theory of “spontaneous generation”.  Which one of the following best explains the apparent success of these experiments?

A.  Oxygen was available in the system

B.  Mild heat was applied to the system

C.  The food source was able to support life

D.  Microorganisms were already present

(i)  Which response (A-D) is the best explanation? (1 mark)

(ii ) Briefly explain your reasoning for your choice (2 marks)

Streptococcus pneumoniae (pneumococcal pneumonia) is one of the most common causes of bacterial pneumonia.  S. pneumoniae is a Gram-positive, encapsulated coccus that grows in short chains.  It is commonly treated in both children and adults with the β-lactam antibiotic amoxicillin.  Briefly describe how amoxicillin targets this bacterium and rleate this to whether it has a bactericidal or bacteriostatic effect.       (3 marks)

There are three common mechanisms of horizontal gene transfer used by bacteria:

• Conjugation
• Transformation 
• Transduction 

A.  Give one contrasting or unique feature for each of the above three mechanisms of horizontal gene transfer.     (3 marks)

B.  A very small number of bacteria are considered to be naturally competent or transformable.  Which feature of these bacteria makes them "transformable"?     (1 mark)

C.  When genetic material is transferred from one bacterium to another, there are three possible fates for the transferred DNA.  Choose one of those fates and briefly explain the outcome in terms of the recipient cell.       (1 + 2 marks)

Which one of the following classes of antibiotics interferes with protein synthesis?

There are 4 major classes of antimicrobial resistance mechanisms employed by bacteria:

1. Drug target modification
2. Drug molecule modification
3. Altered permeability / efflux
4. Metabolic bypass

Nalidixic acid is an antibiotic that inhibits enzymes involved in the DNA replication process. Some strains of Pseudomonas aeruginosa are resistant to nalidixic acid and have been shown to have lower intracellular concentrations of the antibiotic when compared with sensitive strains. Which ONE of the following most likely explains the mechanism of resistance of P. aeruginosa to nalidixic acid?  

All of the following are ways to treat water (potentially contaminated by microbes) to make it safe for drinking, EXCEPT:

Good food handling practices have a mantra of "keep hot foods hot and cold foods cold", in terms of temperatures, this translates to ≤ 5°C or > 60°C.  Which one of the following statements best explains why this is the case?

DNA repair mechanisms can help alleviate the effects of:

Which one of the following best describes asepsis?