Straighterline Micro 250
Straighter line Micro 250 final prep exam
with solved solutions 2025
Which class of eukaryotic microorganisms can be subdivided into groups such as
Mastigophora, Sarcodina, Ciliophora, and Apicomplexa?
A. Helminths
B. Algae
C. Protozoa
D. Fungi - Correct Ans-Protozoa
Genetic material can be excised from one chromosome and directly integrated into
another via
A. conjugation.
B. transformation.
C. transduction.
D. transposons. - Correct Ans-transposons.
Which immune cell secretes numerous cytokines that help to coordinate the response of
other immune cells?
A. B cell
B. TH cell
C. TC cell
D. Platelets - Correct Ans-TH cell
Which of the following enzymes are used to amplify DNA during PCR?
A. restriction endonuclease
B. DNA polymerase
C. reverse transcriptase
1|Page
,Straighterline Micro 250
D. DNA ligase - Correct Ans-DNA polymerase
In the nitrogen cycle, which of the following steps involves removal of nitrogen from the
atmosphere by bacteria? - Correct Ans-nitrogen fixation, In nitrogen fixation, nitrogen is
removed from the atmosphere by nitrogen-fixing bacteria and converted to ammonia.
If enough h+ ions are added to pure water to raise the H+ concentration of the solution
to ten times higher than the original concentration, what is the resulting OH-
concentration of the solution? - Correct Ans-10 -8M
Fungi are able to reproduce asexually by creating conidiospores and sporangiospores.
Which of the following is an accurate explanation for why it is advantageous that they
are also capable of sexual reproduction?
Select one:
a. Asexually produced offspring are more likely to compete for resources and will kill off
the parental fungi.
b. Fungi normally produce sexually but produce asexually in harsh conditions such as
severe drought.
c. Offspring from two parents may have variations in form and function that contribute to
survival of the species.
d. Sexual reproduction produces more offspring at a faster rate than spore formation. -
Correct Ans-Offspring from two parents may have variations in form and function that
contribute to survival of the species.
In a laboratory bacterial cell culture that has been infected by a virus, plaques are areas
in which
Select one:
a. bacterial cells are resistant to the virus and have not been infected.
b. there is no nutrient available for the bacteria to grow.
c. the virus has spread and left behind the remains of dead cells.
d. the virus has not yet spread to that area of cells. - Correct Ans-the virus has spread
and left behind the remains of dead cells.
The sun's energy is delivered as discrete packets that travel as waves and are called
Select one:
a. ATP.
b. carotenoids.
c. NADP.
d. photons. - Correct Ans-photons.
Which of the following is a characteristic of aerobic respiration?
Select one:
a. Oxygen-containing ions act as the final electron acceptors in electron transport.
b. The process includes glycolysis, the Krebs cycle, and the electron transport chain.
c. Aerobic respiration produces a total of 2 ATP molecules.
2|Page
,Straighterline Micro 250
d. Aerobic respiration produces lactic acid. - Correct Ans-The three stages of aerobic
respiration are glycolysis, the Krebs cycle, and the electron transport chain.
n completing protein synthesis in a prokaryote, what basic message is carried by a
specialized codon that has no corresponding tRNA?
Select one:
a. "Fold peptide chain."
b. "Terminate here."
c. "Add cofactor."
d. "Clip starting amino acid." - Correct Ans-"Terminate here." The specialized codon
signals the end of protein synthesis; there is not RNA because it is only needed if the
process is to continue.
Microbial drug resistance can be caused by mutations or by introduction of new genes
into a population. Which of the following can only be caused by the introduction of new
genes into a population?
Select one:
a. a metabolic pathway in the bacterium is shut down
b. binding sites for the drug are reduced in number or affinity to the drug
c. new enzymes that inactivate the drug are synthesized
d. uptake of the drug into the bacterium is diminished - Correct Ans-new enzymes that
inactivate the drug are synthesized. This can only occur if new genes are introduced
into the population.
Why do the hands, feet, and breasts have more lymphatic vessels for host defense than
other areas of the human body?
Select one:
a. They have a high risk for infection due to frequent contact.
b. They have a greater density of nerves.
c. They require complex movement of fluids from the extremities.
d. They are located a long distance from the thalamus. - Correct Ans-They have a high
risk for infection due to frequent contact.
Penicillin functions as an antimicrobial agent by inhibiting bacterial
Select one:
a. cell wall synthesis.
b. folic acid synthesis.
c. protein synthesis.
d. RNA and DNA function. - Correct Ans-cell wall synthesis. Penicillin belongs to a class
of antibacterial agents that interfere with the production of the material that makes up
the bacterial cell wall. The bacteria must constantly replace this material or they will
become susceptible to rupture due to osmotic pressure.
If enough ions are added to pure water to raise the concentration of the solution to ten
times higher than the original concentration, what is the resulting concentration of the
solution? - Correct Ans-
3|Page
, Straighterline Micro 250
The study of evolutionary relationships among organisms is called - Correct Ans-
phylogeny
The three cell types discussed, eukaryotes, archaea, and bacteria, all derived from -
Correct Ans-Last Universal Common Ancestor
Organisms called parasites are - Correct Ans-always harmful to their host.
Which of the following does not indicate microbe involvement in energy and nutrient
flow - Correct Ans-Thermal hot springs warmed by heat from earth's interior
The subatomic particles that surround the nucleus are the - Correct Ans-Electrons
The number one worldwide infectious diseases are - Correct Ans-respiratory diseases
A fat is called _____ if all carbons of the fatty acid chain are single-bonded to 2 other
carbons and 2 hydrogens. - Correct Ans-saturated
One technique for staining bacteria for viewing under the microscope is called the Gram
stain. In this technique, alcohol is used as a decolorizer because it degrades the outer
membrane found in some bacteria. What chemical component of the cell does alcohol
affect? - Correct Ans-lipid
If a microbiologist is studying a specimen at a total magnification of 950X, what is the
magnifying power of the objective lens if the ocular lens is 10X? - Correct Ans-95X
NASA has published a list of criteria for identifying fossil bacteria in samples from Mars,
as part of a search for evidence of life. Which of the following is good evidence for the
presence of bacterial cells? - Correct Ans-cell size of 0.5 to 2 microns
Which type of microscope achieves the greatest resolution and highest magnification? -
Correct Ans-electron
Which of the following is produced by adding 1% to 5% agar to nutrient broth that is
then boiled and cooled? - Correct Ans-a solid medium
a spongiform encephalopathy of humans - Correct Ans-Creutzfeldt-Jacob disease
The term that refers to flagella at both poles of the cell is ______. - Correct Ans-
amphitrichous
In the condition called athlete's foot, the fungus Trichophyton consumes the keratin
protein found in hair, nails, and dead skin. Which of the following descriptors does not
apply to Trichophyton? - Correct Ans-saprobe
4|Page
Straighter line Micro 250 final prep exam
with solved solutions 2025
Which class of eukaryotic microorganisms can be subdivided into groups such as
Mastigophora, Sarcodina, Ciliophora, and Apicomplexa?
A. Helminths
B. Algae
C. Protozoa
D. Fungi - Correct Ans-Protozoa
Genetic material can be excised from one chromosome and directly integrated into
another via
A. conjugation.
B. transformation.
C. transduction.
D. transposons. - Correct Ans-transposons.
Which immune cell secretes numerous cytokines that help to coordinate the response of
other immune cells?
A. B cell
B. TH cell
C. TC cell
D. Platelets - Correct Ans-TH cell
Which of the following enzymes are used to amplify DNA during PCR?
A. restriction endonuclease
B. DNA polymerase
C. reverse transcriptase
1|Page
,Straighterline Micro 250
D. DNA ligase - Correct Ans-DNA polymerase
In the nitrogen cycle, which of the following steps involves removal of nitrogen from the
atmosphere by bacteria? - Correct Ans-nitrogen fixation, In nitrogen fixation, nitrogen is
removed from the atmosphere by nitrogen-fixing bacteria and converted to ammonia.
If enough h+ ions are added to pure water to raise the H+ concentration of the solution
to ten times higher than the original concentration, what is the resulting OH-
concentration of the solution? - Correct Ans-10 -8M
Fungi are able to reproduce asexually by creating conidiospores and sporangiospores.
Which of the following is an accurate explanation for why it is advantageous that they
are also capable of sexual reproduction?
Select one:
a. Asexually produced offspring are more likely to compete for resources and will kill off
the parental fungi.
b. Fungi normally produce sexually but produce asexually in harsh conditions such as
severe drought.
c. Offspring from two parents may have variations in form and function that contribute to
survival of the species.
d. Sexual reproduction produces more offspring at a faster rate than spore formation. -
Correct Ans-Offspring from two parents may have variations in form and function that
contribute to survival of the species.
In a laboratory bacterial cell culture that has been infected by a virus, plaques are areas
in which
Select one:
a. bacterial cells are resistant to the virus and have not been infected.
b. there is no nutrient available for the bacteria to grow.
c. the virus has spread and left behind the remains of dead cells.
d. the virus has not yet spread to that area of cells. - Correct Ans-the virus has spread
and left behind the remains of dead cells.
The sun's energy is delivered as discrete packets that travel as waves and are called
Select one:
a. ATP.
b. carotenoids.
c. NADP.
d. photons. - Correct Ans-photons.
Which of the following is a characteristic of aerobic respiration?
Select one:
a. Oxygen-containing ions act as the final electron acceptors in electron transport.
b. The process includes glycolysis, the Krebs cycle, and the electron transport chain.
c. Aerobic respiration produces a total of 2 ATP molecules.
2|Page
,Straighterline Micro 250
d. Aerobic respiration produces lactic acid. - Correct Ans-The three stages of aerobic
respiration are glycolysis, the Krebs cycle, and the electron transport chain.
n completing protein synthesis in a prokaryote, what basic message is carried by a
specialized codon that has no corresponding tRNA?
Select one:
a. "Fold peptide chain."
b. "Terminate here."
c. "Add cofactor."
d. "Clip starting amino acid." - Correct Ans-"Terminate here." The specialized codon
signals the end of protein synthesis; there is not RNA because it is only needed if the
process is to continue.
Microbial drug resistance can be caused by mutations or by introduction of new genes
into a population. Which of the following can only be caused by the introduction of new
genes into a population?
Select one:
a. a metabolic pathway in the bacterium is shut down
b. binding sites for the drug are reduced in number or affinity to the drug
c. new enzymes that inactivate the drug are synthesized
d. uptake of the drug into the bacterium is diminished - Correct Ans-new enzymes that
inactivate the drug are synthesized. This can only occur if new genes are introduced
into the population.
Why do the hands, feet, and breasts have more lymphatic vessels for host defense than
other areas of the human body?
Select one:
a. They have a high risk for infection due to frequent contact.
b. They have a greater density of nerves.
c. They require complex movement of fluids from the extremities.
d. They are located a long distance from the thalamus. - Correct Ans-They have a high
risk for infection due to frequent contact.
Penicillin functions as an antimicrobial agent by inhibiting bacterial
Select one:
a. cell wall synthesis.
b. folic acid synthesis.
c. protein synthesis.
d. RNA and DNA function. - Correct Ans-cell wall synthesis. Penicillin belongs to a class
of antibacterial agents that interfere with the production of the material that makes up
the bacterial cell wall. The bacteria must constantly replace this material or they will
become susceptible to rupture due to osmotic pressure.
If enough ions are added to pure water to raise the concentration of the solution to ten
times higher than the original concentration, what is the resulting concentration of the
solution? - Correct Ans-
3|Page
, Straighterline Micro 250
The study of evolutionary relationships among organisms is called - Correct Ans-
phylogeny
The three cell types discussed, eukaryotes, archaea, and bacteria, all derived from -
Correct Ans-Last Universal Common Ancestor
Organisms called parasites are - Correct Ans-always harmful to their host.
Which of the following does not indicate microbe involvement in energy and nutrient
flow - Correct Ans-Thermal hot springs warmed by heat from earth's interior
The subatomic particles that surround the nucleus are the - Correct Ans-Electrons
The number one worldwide infectious diseases are - Correct Ans-respiratory diseases
A fat is called _____ if all carbons of the fatty acid chain are single-bonded to 2 other
carbons and 2 hydrogens. - Correct Ans-saturated
One technique for staining bacteria for viewing under the microscope is called the Gram
stain. In this technique, alcohol is used as a decolorizer because it degrades the outer
membrane found in some bacteria. What chemical component of the cell does alcohol
affect? - Correct Ans-lipid
If a microbiologist is studying a specimen at a total magnification of 950X, what is the
magnifying power of the objective lens if the ocular lens is 10X? - Correct Ans-95X
NASA has published a list of criteria for identifying fossil bacteria in samples from Mars,
as part of a search for evidence of life. Which of the following is good evidence for the
presence of bacterial cells? - Correct Ans-cell size of 0.5 to 2 microns
Which type of microscope achieves the greatest resolution and highest magnification? -
Correct Ans-electron
Which of the following is produced by adding 1% to 5% agar to nutrient broth that is
then boiled and cooled? - Correct Ans-a solid medium
a spongiform encephalopathy of humans - Correct Ans-Creutzfeldt-Jacob disease
The term that refers to flagella at both poles of the cell is ______. - Correct Ans-
amphitrichous
In the condition called athlete's foot, the fungus Trichophyton consumes the keratin
protein found in hair, nails, and dead skin. Which of the following descriptors does not
apply to Trichophyton? - Correct Ans-saprobe
4|Page
