Microbio Exam 1

You have discovered a compound that inhibits the placement of sterols in the plasma membrane. What can you deduce about the efficacy of this drug?

this drug will likely be broadly effective against eukaryotic cells but carries a high risk of systemic toxicity in human patients

Why is the acid-fast stain clinically useful?

It identifies the causative agents of leprosy and tuberculosis.

What happens when you place a bacterial cell into a hypertonic solution?

The cell will undergo plasmolysis.

Which of the following is true about endospores?

Endospores are highly resistant to environmental stress such as heat, drying, freezing, and radiation.

The genetic material of bacteria can be found in the

nuceloid

Which of the following is false about the bacterial cytoskeleton?

The bacterial cytoskeleton contains actin and tubulin proteins.

Penicillin (an antibiotic that prevents peptidoglycan from forming during cell division) is added to a bacterial culture, and after several hours the bacteria are placed in a hypotonic environment. What is the likely outcome?

The cells will lyse due to a weakened cell wall.

Which of the following processes is incorrectly matched to its description?*

Phagocytosis: Imports undissolved substances but not whole cells or viruses

Fungal infections are called

mycoses

Which person may be at increased risk for mycoses?

either those with weakened immune systems or those who have had their normal microbiome disrupted by antibiotic therapy

A researcher discovers a chemical compound which prevents the incorporation of ergosterol in the plasma membrane. We can predict that this compound would be toxic to which kinds of organisms?

Fungi

Where is the "mucocilliary escalator" located in the human body?

respiratory tract

Prokaryotic and eukaryotic ribosomes share which of the following features?

composed of a large and a small subunit and composed of protein and rRNA

Which type of vesicle/vacuole is incorrectly matched with its description?

Secretory vesicle: Replenishes the lipid bilayer and deliver proteins for incorporation into the membrane

Mitochondria do not participate in which function?

motility

Which of the following is true about ribosomes?

Prokaryotic ribosomes have a lower overall mass and diameter than eukaryotic ribosomes.

A previously undescribed infection has been detected among inhabitants in an isolated village in a remote tropical rainforest. When serum from an infected individual is passed through a filter, the infection can be transmitted to laboratory animals. Nothing is observed when the serum is examined with a light microscope at the highest magnification. Biochemical tests show the presence of RNA and protein but no carbohydrates or lipids. This data is consistent with what type of infectious agent?

virus

Retroviruses use the enzyme reverse transcriptase to

direct the production of DNA from a single-stranded RNA genome.

Robert Koch helped establish the germ theory of disease by discovering that anthrax was caused by a bacterial microorganism. After he isolated and purified the same bacteria from several diseased animals, what would be the next step in order to show that this bacteria caused anthrax?

introduce the bacteria into a new mouse to see if it established the same infection.

The goal of the streak plate technique is to

isolate a pure culture for study from a single colony.

Louis Pasteur's S-necked flask experiment strengthened the theory of

biogenesis

Microbes and humans have evolved a variety of where microbes help the host.

symbiotic; commensalism

A student was in a hurry to finish lab and forgot to apply the final counterstain (safrain) during a Gram stain procedure. Which statement below best describes the expected result when the stain is viewed under the microscope?

Gram-positive cells will appear purple, while Gram-negative cells will remain colorless and nearly invisible.

which of the following is incorrectly matched ?

Salt: Formed by the combination of hydrogen ions (H+) and hydroxide ions (OH-)

Compared to a solution with a pH value of 4, a solution with a pH value of 2 has .. ions.

100x as many

Which of the following statements does not correctly describe electrolytes?

Electrolytes are ionic compounds that can cause damage if consumed during heavy exercise.

Plasma membranes, the key boundary layer of cells, are composed of amphipathic molecules called phospholipids. Why would neither purely hydrophilic nor purely hydrophobic molecules be a suitable molecule for plasma membranes?

Hydrophilic molecules would dissolve in the aqueous environment in which cells live, disrupting the structural integrity of the cell, and hydrophobic molecules would be unable to interact with the aqueous environment in which cells live.

Why are Gram-negative bacteria more resistant than Gram-positive bacteria damaged by certain chemical agents like lysozyme?

Gram-negative bacteria have an outer membrane as part of their cell wall.

Which description of antigenic drift and antigenic shift in the influenza virus is incorrectly matched?

Antigenic drift: Often involves reassortment of viral strains in an animal host followed by a "species jump" to humans.

Which of the following tests works by detecting viral nucleic acid?

PCR

Challenges in developing effective antiviral drugs with minimal side effects to the patient include

viruses use the cell's own machinery and metabolism for replication.

Mycobacterium tuberculosis are grown for 80 hours. During that time, they go through four generations of growth. What is the generation time?

20 hours

In which growth phase do bacteria grow exponentially?

log phase

Which of the following is not an environmental factor that would affect the growth of E. coli?

generation time of E. coli

Which term represents the temperature at which bacteria grow the fastest?

optimal temperature

Microbes that primarily infect the lungs are likely to be classified as which of the following?

obligate aerobe

Which of the following could result in the wrong patient diagnosis and improper treatment?

using a cotton-tipped swab to collect a suspected pathogen

Which of the following is an indirect cell-counting method?

turbidity measurement

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