MICROBIO exam 2

Which of the following statements about viruses is FALSE?

Viruses use their own catabolic enzymes.

Why do most scientists agree that viruses are nonliving entities?

They are not composed of cells.

Which of the following is NOT used as a criterion to classify viruses?

biochemical tests

Which of the following statements about viral spikes is FALSE?

They are found only on nonenveloped viruses.

The definition of lysogeny is

phage DNA is incorporated into host cell DNA.

An envelope is acquired during which of the following steps?

Release

A viroid is a(n)

Infectious piece of RNA without a capsid

An infectious protein is a

Prion

The term aerotolerant anaerobe refers to an organism that

does not use oxygen but tolerates it.

Which of the following is an organic growth factor?

vitamin B1

Which enzyme catalyzes the reaction: O₂- + O₂- + 2H⁺ → H₂O₂ + O₂?

superoxide dismutase

Which of the following is an advantage of the standard plate count?

determines the number of viable cells

Which of the following is an advantage of the direct microscopic count?

requires no incubation time

Most bacteria reproduce by

binary fission.

The figure shows a typical bacterial growth curve with the y-axis indicating the log of the number of bacteria and the x-axis indicating time in culture. In the figure, which sections of the graph illustrate a logarithmic change in cell numbers?

b and d

During which growth phase will gram-positive bacteria be most susceptible to penicillin?

log phase

Which of the following is the best definition of generation time?

the length of time needed for a cell to divide

Three cells with generation times of 60 minutes are inoculated into a culture medium. Assuming no lag phase takes place, how many cells are there after 5 hours?

96

Which of the following compounds is NOT an enzyme?

coenzyme A

Which of the graphs in the figure best illustrates the activity of an enzyme that is saturated with substrate?

C

Which of the following statements are TRUE?
1-Electron carriers are located at ribosomes.
2-ATP is a common intermediate between catabolic and anabolic pathways.
3-ATP is used for the long-term storage of energy and so is often found in storage granules.
4-Anaerobic organisms are capable of generating ATP via respiration.
5-ATP can be generated by the flow of protons across protein channels.

2: ATP is a common intermediate between catabolic and anabolic pathways.

4: Anaerobic organisms are capable of generating ATP via respiration.

5: ATP can be generated by the flow of protons across protein channels.

Which compound is being reduced in the reaction shown in the figure?

NAD+

How is ATP generated in the reaction shown in the figure?

substrate level phosphorylation

Which of the following is the best definition of oxidative phosphorylation?

A proton gradient allows hydrogen ions to flow back into the cells through transmembrane protein channels, releasing energy that is used to generate ATP.

Which of the following statements about anaerobic respiration is FALSE?

It involves the reduction of an organic final electron acceptor.

What is the fate of pyruvic acid in an organism that uses aerobic respiration?

It is converted into acetyl CoA.

From the list below, which is NOT produced during the Krebs cycle?

NADPH

A bacterium that only possesses the ability to ferment obtains energy

by glycolysis only

All of the following are required in the reactions of microbial respiration EXCEPT

oxygen

A bacterium such as Pseudomonas uses nitrate as a final electron acceptor in an electron transport system. All the below statements are true EXCEPT

They require light

Assume you are working for a chemical company and are responsible for growing a yeast culture that produces ethanol. The yeasts are growing well on the maltose medium but are not producing alcohol. What is the most likely explanation?

O₂ is in the medium.

Refer to the figure. In aerobic respiration, where is water formed?

D

In the figure, where is ATP produced

E

In the figure, the structure labeled 1 is

A plasma membrane

In the figure, the path labeled "2" is the flow of

Protons

What is the most acidic place in the figure?

A

Which organism is NOT correctly matched to its energy source?

photoautotroph - CO₂

Which of the following uses CO₂ for carbon and H₂ for energy?

chemoautotroph

Which of the following uses glucose for carbon and energy?

chemoheterotroph

Cyanobacteria are a type of

photoautotroph

Viruses

Simply want to replicate

Viruses are not considered living because

They have no ribosomes

Capsomeres

Are the protein units that make up the capsid

Budding, when it refers to viruses, has to do with

Replication of enveloped viruses.

Clostridium botulinum produces a toxin because

It contains a prophage.

The best way to prevent a viral infection is

Get vaccinated if a vaccine is available.

If you have a pet potato and you don’t want it to get sick, keep it away from

Viroids.

If you see a deer staggering around in the woods, you might want to avoid it
because it may have

Chronic Wasting Disease.

Prions

Are altered brain proteins

The breakdown of lactose into glucose and galactose

Is a spontaneous reaction.

ATP is the energy currency of living cells because

The amount of energy that it takes to make ATP is reasonable for the cell.

Enzymes

All of the above.

Enzyme activity

Slows down at temperatures below and greater than optimal temperature

Wild type E. coli does not require as a nutrient

Essential metabolites.

With respect to temperature, organisms that grow optimally at human body
temperature of 37oC are referred to as

Mesophiles

Which statement is correct?

Humans, dogs and cats produce superoxide and superoxide dismutase.

In which phase(s) of growth are bacterial cells growing most rapidly?

Log phase only

A microorganism that is found in an alkaline (pH 10.0) environment

Will probably die in the neutral pH medium.

Which of these methods might count dead cells found in an original bacterial
culture?

Direct Microscopic Count.

Proteins are not considered nutrients for a cell because

They are simply too big to get into the cell.

Nitrogen fixation

Occurs in some microorganisms

Which statement is correct?

E.coli is a chemoheterotroph while most of the Archaea are
chemoautotrophs

The type of ATP generation where a phosphate is donated directly from an
organic molecule is

Substrate-level phosphorylation.

One purpose of fermentation is

To reduce pyruvic acid.

The oxidation of glucose ultimately to carbon dioxide is an example of

Catabolism.

Oxidative phosphorylation is DIRECTLY associated with

The Electron Transport Chain

In biological oxidations, what is typically removed from a molecule?

Hydrogen atoms

Streptococcus typically carries out fermentation only because

It is missing an enzyme in the Kreb’s Cycle.

NAD+ is

A coenzyme.

Most of the CO2 released by an organism performing respiration is released in

The Krebs Cycle.

A major difference between fermentation and respiration is

Fermentation uses an organic final electron acceptor.

We need molecular oxygen (O2)

To serve as a final electron acceptor only

ATP Synthase is involved in

Oxidative phosphorylation

The Proton Motive Force

transports certain amino acids into the cell.

The Core Pathways

Are glycolysis and the Kreb’s Cycle.

The poison, cyanide, interferes DIRECTLY with

The Electron Transport Chain.

E.coli, in the presence of molecular oxygen and nitrate, predominantly carries out

Aerobic respiration

Which of the following contains the most energy?

NADH

Fatty acids, which are break-down products from fats, enter metabolism

In one of the core pathways

What is the fate of pyruvic acid in an organism that uses anaerobic respiration?

Most of its carbons are oxidized in the Kreb’s Cycle.

Which of the following statements is true?

Viruses are not cellular, so they are not considered to be alive.

Which is NOT associated with a viral capsid?

All of the above are associated with viral capsids

Viral envelopes

Are derived from the cell membrane of the host cell

When an animal DNA virus infects a cell

DNA replication takes place inside of the host cell.

One thing that a bacteriophage normally does that an animal virus may or may not do
is

Lyse the host cell.

If you were setting up an experiment on viruses, which of the following would be
important to maintain the viruses used in the experiment?

Host cells

An oncogenic virus

is a cancer-causing animal virus

Another name for mad cow disease is

Bovine spongiform encephalopathy.

A microbiology student noticed that a culture broth tube was turbid at the surface but
clear throughout the rest of the tube. What can this student correctly conclude?

The organisms are aerobes.

A disadvantage to the dilution and plating technique is

It may not count aerobes buried in the agar.

Stationary growth phase is achieved because

Cells run out of nutrients and end products build up.

When lactic acid is converted into pyruvic acid, NADH is formed. The reaction that
forms NADH is a(an)

Reduction.

Microorganisms found relatively deep below the surface of the Earth are most likely

Chemoautotrophs.

Which statement is true?

Glucose has more energy than two pyruvic acids.

What is transferred to NAD+ during the breakdown of glucose?

Electrons

In a test tube of medium constantly exposed to oxygen at the surface of the medium,
E. coli, which can respire and ferment, forms some acidic fermentation products.
This occurs because

Oxygen is being depleted at the bottom of the tube

Phosphorylation

is the addition of phosphate to a molecule.

Once pyruvic acid enters the fermentation reactions, the most important and direct
product of fermentation that benefits the fermenting cell is

NAD+

The correct sequence of events in an animal virus lytic infection cycle is

Attachment, penetration, uncoating, biosynthesis, maturation and
release.

Viruses

Vary in shape and contain nucleic acid