Question

What is the primary method used by microbes to have water cross the membrane?
Choose one:

A. pumps

B. Membranes do not allow water into or out of cells.

C. diffusion

D. pinocytosis

E. aquaporins

Which of the following is the best example of an extremophile?
Choose one:

A. the facultative anaerobe Bacillus cereus

B. the Gram-negative plague-causing bacteria Yersinia pestis

C. the hyperthermophile bacteria Methanopyrus kandleri

D. the barotolerant bacterial strain DSK1

Of the reactions that involve reactive oxygen species as shown in the figure below, the one marked  

$incorrect_tab.png$ _____ is the only one not catalyzed by an enzyme.

Which of the following adaptations is most important in helping microbes be successful in an extreme environment such as a very low pH that would harm normal microbes?
Choose one:

A. altered proteins to allow them to function better in that environment

B. altered membrane permeability to remove toxins

C. altered DNA flexibility to allow more genes to be expressed

D. altered peptidoglycan thickness to prevent molecules from getting into the cell

Which of the following would have the greatest effect on cell function due to changes in pH?
Choose one:

A. changing the fatty acid interactions in membranes, thus harming the integrity of the hydrophobic barrier

B. causing carbohydrate changes so that they would no longer serve as proper nutrient sources

C. changing nucleic acids to nucleic bases and interfering with the DNA code

D. disrupting protein secondary structure, thus decreasing enzyme activity

Why wouldn't the majority of microbial species inhabiting the human intestine be pathogenic?
Choose one:

A. There really aren't that many human pathogens, so it would not be possible to have that many out of the 500 different species that are normally present.

B. If there were a lot of pathogens, they would constantly be battling for domination over the intestine, so the end result would be the most powerful pathogen, thus greatly reducing the number of species present.

C. Having a lot of pathogens inhabiting a normal intestine would mean that the individual would constantly be sick and thus at a disadvantage for survival.

D. Since the pathogens use the probiotic microbes as food, if there were too many pathogenic species, it would reduce the available food supply, thus causing them to starve.

Which of the following is a common compatible solute used by microbes to prevent water loss in a hypertonic medium?
$incorrect_tab.png$ Choose one:

A. potassium ion

B. sodium ion

C. chloride ion

D. fluoride ion

E. hydroxide ion

Which of the following techniques would be best to use to study extremophiles that cannot be cultured in normal laboratory conditions?
Choose one:

A. the polymerase chain reaction to amplify the DNA to have enough for further analysis

B. gas chromatography to study the lipid composition

C. peptide analysis to study protein fragmentsHalophiles

D. spectrophotometry to measure the cell concentration

Halophiles

Choose one:

A. must have 10%–20% NaCl levels to grow

B. must have 0.2%-5% NaCl levels to grow.

C. require halogen elements in large quantites.

D. live in the ocean.

Answer 1

Answer 1:

Cells of microbes, like other organisms, need to exchange water for life processes. It mainly takes via diffusion and through aquaporin proteins. These are integral membrane proteins and form a channel from cell membrane to cell interior. Water moves via these channels by diffusion. Thus, the primary method used by microbes to have water cross the membrane is: (c) diffusion.

Answer 2:

Extremophiles are those microbes which can survive in harsh extremes of temperature or pH or other externalities. The best example from among the given choices is:

C. the hyperthermophile bacteria Methanopyrus kandleri.

B is the only one not catalyzed by an enzyme. FAD *O," Superoxide radical union A '0," + H+ H,O, Hydrogen peroxide Fe2+ Fe3+ H, PH+ + OH Hydroxyl radical B. c. 2H,O, 2H,0 +02 2H,O, 2H2O + NAD D.