Quiz

QUIZ

1. What is the last thing that separates the cell completely when binary fission takes place in prokaryotic cells?

a. A cell wall forms between the daughter cells. b. A Z-ring is formed c. The cell membrane is built between the cell halves. d. The cell membrane constricts like purse strings.

Answer: a. The separation of the cell occurs when there is a cell wall built between the two daughter cells. The other choices do not effectively separate the cell.

2. In which phase of cell growth in medium is there shock to the organisms so they do not divide?

a. Log phase b. Stationary phase c. Lag phase d. Decline phase

Answer: c. In the lag phase, there is the presence of an inoculum. Because of shock to the organisms and the beginnings of cellular growth without cell division, the cells do not immediately begin to divide.

3. What technique will be able to directly measure the bacterial cell count in a dilute solution containing bacteria?

a. Pour method b. Most probable number method c. Membrane filtration d. Spread method

Answer: c. With membrane filtration, a known quantity of the suspension is filtered and bacteria are trapped and allowed to grow into colony-forming units. The number of bacterial colonies detected is divided by the quantity of liquid filtered. It directly measures the CFUs in a dilute solution.

4. Which technique is an indirect method for estimating the cell count in a liquid medium?

a. Pour method b. Spectrophotometer c. Membrane filtration d. Spread method

Answer: b. The spectrophotometer measures turbidity, which will increase as the cell count increases. It indirectly measures the cell count.

5. Which organisms tolerate a specific oxygen concentration that is less than atmospheric oxygen levels?

a. Microaerophilic b. Aerotolerant anaerobes c. Facultative anaerobes d. Strict anaerobes

Answer: a. The microaerophilic organisms tolerate a specific oxygen concentration but it will be less than the concentration of oxygen in the atmosphere.

6. What is the purpose of superoxide dismutase, catalase, and peroxidase in the cell?

a. They are important in oxygen metabolism. b. They get rid of reactive oxygen species. c. They participate in aerobic respiration. d. They get rid of waste products in the cell.

Answer: b. These are enzymes that act to get rid of reactive oxygen species that are generated as part of the respiratory processes in the cell.

7. What is not a way that thermophiles cope with their high-temperature environment?

a. They have high guanine-cytosine base pair ratios. b. They have specialized thermoenzymes. c. They have antifreeze proteins in their cytoplasm. d. They have high ratios of saturated to unsaturated fatty acids.

Answer: c. Each of these is characteristic of thermophiles except that they do not need antifreeze proteins.

8. Which culture medium is used to grow fastidious organisms?

a. Selective media b. Enriched media c. Differential media d. Complex media

Answer: b. There are many types of media, including enriched media that contains special vitamins and nutrients to grow particularly fastidious organisms.

9. Which is an example of moist-heat sterilization in a laboratory?

a. Oven-heating b. Flame-heating c. Autoclave-heating d. Incineration

Answer: c. Autoclaves use a combination of temperature and pressure in order to kill microorganisms in a laboratory.

10. Which organism is least likely to be killed using boiling techniques?

a. Staphylococcus aureus b. Escherichia coli c. Streptococcus pyogenes d. Clostridium botulinum

Answer: d. Clostridium botulinum involves the production of heatstable spores that don’t get killed unless there is high pressure and temperature applied for a prolonged period of time.