An organism that grows best at high osmolarity is called
Choose one:
A. a barophile.
B. an alkaliphile.
C. a halophile.
D. a psychrophile.
C. a halophile.
Halophiles thrive in high-solute environments. Alkaliphiles grow best in high pH, psychrophiles grow best in cold environments, and barophiles grow under high-pressure conditions.
Halophiles
Choose one:
A. live in the ocean.
B. require halogen elements in large quantities.
C. must have 10%–20% NaCl levels to grow.
D. must have 0.2%–5% NaCl levels to grow.
C. must have 10%–20% NaCl levels to grow.
Halophiles must have NaCl concentrations of 2–4 M, which is 10%–20%, to grow, but their intracellular chloride levels are considerably lower. Oceans are about 3.5% NaCl.
The figure below shows the growth zones in a standing test tube.
Correctly match the zone with the type of microbe that can be found there.
Choose one:
A. 1 – aerobic; 2 – anaerobic; 3 – facultative; 4 – microaerophilic
B. 1 – facultative; 2 – anaerobic; 3 – microaerophilic; 4 – aerobic
C. 1 – facultative; 2 – aerobic; 3 – microaerophilic; 4 – anaerobic
D. 1 – anaerobic; 2 –aerobic; 3 – facultative; 4 – microaerophilic
C. 1 – facultative; 2 – aerobic; 3 – microaerophilic; 4 – anaerobic
Oxygen diffuses from the atmosphere through the fluid in the tube slowly, so aerobes will be at the top of the tube, anaerobes at the bottom, microaerophiles just beneath the aerobes, and facultative throughout.
Which of the following sentences is correct?
Choose one:
A. Sterilization kills all cells, spores, and viruses on an object; disinfection removes pathogens from inanimate surfaces; and antisepsis removes pathogens from the surface of living tissues.
B. Sterilization kills all cells, spores, and viruses on an object; antisepsis removes pathogens from inanimate surfaces; and disinfection removes pathogens from the surface of living tissues.
C. Disinfection kills all cells, spores, and viruses on an object; antisepsis removes pathogens from inanimate surfaces; and sterilization removes pathogens from the surface of living tissues.
D. Disinfection kills all cells, spores, and viruses on an object; sterilization removes pathogens from inanimate surfaces; and antisepsis removes pathogens from the surface of living tissues.
A. Sterilization kills all cells, spores, and viruses on an object; disinfection removes pathogens from inanimate surfaces; and antisepsis removes pathogens from the surface of living tissues.
The correct definitions of these terms are as follows.
Disinfection removes pathogens from inanimate objects.
Sterilization kills all cells, spores, and viruses on an object.
Antisepsis removes pathogens from the surface of living tissues.
Pasteurization limits microbial numbers through
Choose one:
A. refrigeration.
B. high heat.
C. filtration.
D. chemical means.
B. high heat.
Pasteurization relies on high heat, a physical way to kill microbes.
A steam autoclave attempts to kill bacteria through a combination of
Choose one:
A. high pressure and ionizing radiation.
B. ionizing radiation and low temperature.
C. low pH and high temperature.
D. high temperature and high pressure.
D. high temperature and high pressure.
The combination of high temperature and high pressure created in an autoclave is effective at killing many bacteria.
Chemical disinfectants
Choose one:
A. can be used safely on skin.
B. can damage macromolecules in a microbial cell.
C. cannot select microbes for resistance.
D. work equally well in all environments.
B. can damage macromolecules in a microbial cell.
Chemical disinfectants are intended for non-living surfaces, and they generally affect the biomolecules of the cell to stop growth and/or kill the microbes present. Microbes can and do develop resistance due to preexisting adaptations becoming more common.
The term “phage therapy” refers to
Choose one:
A. the use of light energy (photons) to cure viral diseases.
B. the presence of “good” bacteria such as lactobacillus in yogurt.
C. the idea that phages could be used to treat bacterial diseases.
D. high energy radiation treatments.
C. the idea that phages could be used to treat bacterial diseases.
Phages are viruses that infect and may kill bacteria. With the emergence of many antibiotic-resistant strains of bacteria, the idea that phages can be used to kill bacteria is gaining renewed interest.
A woman with irritable bowel syndrome attempts to restore normal
intestinal microflora by ingesting yogurt containing live, active
cultures. This is an example of using
Choose one:
A. probiotics.
B. antibiotics.
C. phage therapy.
D. bioinformatics.
A. probiotics.
A probiotic is a food or nutritional supplement that contains live microorganisms and aims to improve health by promoting beneficial bacteria. Antibiotics are drugs designed to kill bacteria, bioinformatics uses computers to analyze genomes, and phage therapy employs bacterial viruses to kill bacteria.
Microbes can develop resistance to chemical control agents
Choose one:
A. because the microbes develop tolerance to the chemical agents.
B. under very limited conditions.
C. because the chemicals cause cellular and genetic changes allowing the microbes to survive.
D. if low concentrations of the chemical are applied to reduce the number of microbes below target number.
D. if low concentrations of the chemical are applied to reduce the number of microbes below target number.
Chemical agents may not kill microbes if they are not at high enough concentrations, allowing those microbes that have preexisting adaptations for resistance to survive and reproduce. Biofilm formation is another mechanism of resistance as well.
The figure below shows the relationship between external pH and
cytoplasmic pH for several microbes. Which of the identified microbes
is an acidophile?
Choose one:
A. Acidiphilium acidophilum
B. Bacillus pseudofirmus OF4
C. Escherichia coli
D. Bacillus subtilis
A. Acidiphilium acidophilum
Acidophiles prefer pH levels between pH 0 and pH 5. Neutralophiles prefer levels between pH 5 and pH 8. Alkaliphiles prefer levels between pH 9 and pH 11.
One reason most organisms cannot grow at high temperatures is that
Choose one:
A. ribosomes dissociate.
B. diffusion rates slow down.
C. proteins denature.
D. membranes will stiffen.
C. proteins denature.
At high temperatures, noncovalent bonds responsible for protein secondary and tertiary structures will break, leading to protein denaturation. Other changes at high temperatures include increased membrane fluidity and increased diffusion rates. Ribosomes can dissociate at high pressures.
Most human pathogens prefer temperatures similar to
Choose one:
A. psychrophiles.
B. hyperthermophiles.
C. thermophiles.
D. mesophiles.
D. mesophiles.
The human body is at a temperature of about 37°C, which is preferred by mesophiles. Thermophiles prefer temperatures higher than that of humans and psychrophiles prefer temperatures lower than that of humans.