A. Decreased temperatures increase the chances of causing beneficial mutations,

Question

A. Decreased temperatures increase the chances of causing beneficial mutations, thus increasing microbial physiology.

B. Decreased temperatures increase membrane fluidity to allow organisms to take up more nutrients.

C. Slightly increased temperature speeds up the action of enzymes, thus increasing microbial metabolism.

D. Slightly increased temperatures would cause DNA denaturation, thus killing the cell and eliminating microbial physiology.

A. microbes sending out false signals to activate programmed cell death in pathogens

B. microbes using aerobic respiration to use up most of the nutrients, thus limiting the availability to pathogens

C. microbes producing phage to attack pathogenic species in the intestine

D. anaerobic fermenters making products inhibiting other microbes

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.

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

.B. live in the ocean.

C. must have 0.2%–5% NaCl levels to grow.

D. require halogen elements in large quantities.

A. potassium ion

B. sodium ion

C. chloride ion

D. fluoride ion

E. hydroxide ion

Explanation / Answer

How does temperature affect microbial physiology?

C. Slightly increased temperature speeds up the action of enzymes, thus increasing microbial metabolism.  

Generally,an increase intemperature will increase enzyme activity. But if temperatures get too high, enzyme activity will diminish and the enzyme ( protein) will denature. On the other hand, lowering temperature will decrease enzyme activity.

Which of the following would best describe the physiology of intestinal microbes acting as probiotics?

D. anaerobic fermenters making products inhibiting other microbes.  Eg. Lactic acid bacteria produce bacteriocins that kill closely related gram-positive bacteria.

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

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.

The gut flora includes low populations of potentially pathogenic organisms such as Clostridium difficile. Antibiotics that upset the balance of the normal flora can favor both infection by exogenous pathogens and overgrowth by endogenous pathogens.

Halophiles ( salt loving ) - D. require halogen elements in large quantities.

Halophiles require sodium chloride (salt) for growth, in contrast to halotolerant organisms, which do not require salt but can grow under saline conditions.

Which of the following is a common compatible solute used by microbes to prevent water loss in a hypertonic medium ? C. chloride ion

In a higher concentration of dissolved salt outside of the cell (a hypertonic environment), then H2Owill diffuse "out" from the cell and the cell will dehydrate and shrink and cellular metabolism will cease. This phenomenon is called plasmolysis. Bacteria differ with regard to their osmotic needs. For eg., some halophiles actually require salt concentrations approaching 30% whereas many other organisms would be totally inhibited or killed by such high salt concentrations.

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