Midterm Practice Questions

Question 1

Which of the following statements about Gram-positive bacteria is NOT TRUE?
a) Their cell surface contains lipopolysaccharide (LPS)
b) Their cell wall contains peptidoglycan
c) They retain crystal violet upon destaining in the Gram stain
d) They have a plasma membrane
e) An example is Staphylococcus aureus

Answer 1

a) Their cell surface contains lipopolysaccharide (LPS)

Question 2

Horizontal Gene Transfer (HGT) is the transfer of genes between organism

Which is not an example of horizontal gene transfer?
a) A cell picks up DNA from its environment by transformation
b) DNA is transmitted from a parental cell to its offspring by binary fission
c) DNA is exchanged between two cells through conjugation
d) DNA is transmitted through phage by transduction
e) Dissemination of antibiotic resistance genes

Answer 2

b) DNA is transmitted from a parental cell to its offspring by binary fission

Question 3

Which are the three currently accepted domains of living organisms?
a) Archaea, Bacteria, and Eukarya
b) Archaea, Prokaryota, and Eukaryota
c) Bacteria, Fungi, and Protista
d) Bacteria, Prokaryota, and Eukarya
e) Prokaryota, Eukaryota, Viridae

Answer 3

a) Archaea, Bacteria, and Eukarya

Question 4

Viruses are not included in phylogenetic trees for which of the following reasons?
a) Their nucleic acids cannot be sequenced
b) It is too difficult to observe their characteristics
c) They do not have any genes, which prevents genetic analysis
d) They lack a nucleus
e) They are acellular and nonliving

Answer 4

e) They are acellular and nonliving

Phylogenetic trees show evolutionary relationships of living organisms.

Question 5

Which of the following best describes the cell membranes of bacteria that thrive at high
temperatures?
a) Their cytoplasmic membrane phospholipids form a monolayer
b) They have relatively even amounts of saturated and unsaturated fatty acids
c) They have relatively high amounts of saturated fatty acids
d) They have relatively high amounts of unsaturated fatty acids
e) They have pseudopeptidoglycan cell walls

Answer 5

c) They have relatively high amounts of saturated fatty acids

Question 6

The periplasm is:
a) A region in Gram-negative bacteria between the outer-membrane and the capsule
b) A region located within the cytoplasm of Gram-negative and Gram-positive bacteria
c) A region between the cytoplasmic and outer membranes of Gram-negative bacteria
d) The region in the cell wall of Gram-positive bacteria in which the peptidoglycan is found
e) Part of the outer membrane of Gram-negative organisms

Answer 6

c) A region between the cytoplasmic and outer membranes of Gram-negative bacteria

Question 7

Which of the following is not a function associated with the bacterial cytoplasmic membrane?
a) Transport of molecules in and out of cytoplasm
b) Lipoprotein anchoring of peptidoglycan
c) Detection of environmental signals
d) Separation of charge across the membrane and energy generation
e) Provide a barrier separating the inside of the cell from the outside

Answer 7

b) Lipoprotein anchoring of peptidoglycan

Question 8

Bacteria mainly use flagella for:
a) Respiration
b) Motility
c) Surface adhesion
d) Cell division
e) Immune evasion

Answer 8

b) Motility

Question 9

Which method of microscopy would be most useful for visualizing the S layer of the archaeon
Thermoproteus tenax?
a) Dark field microscopy
b) Transmission electron microscopy
c) Bright field microscopy
d) Phase contrast microscopy
e) Fluorescence microscopy

Answer 9

b) Transmission electron microscopy

TEM: 2D, high-resolution and capable of showing fine structural details

Question 10

Louis Pasteur used swan-necked flasks to demonstrate:
a) That microbes could be cultured in liquid broth
b) The theory of spontaneous generation of microbes
c) That microbes do not arise spontaneously
d) That microbial culture media could be stored for many years
e) That glass vessels were suitable for the growth of microbes

Answer 10

c) That microbes do not arise spontaneously

Question 11

How do Archaea differ from Bacteria?
a) Archaea are found exclusively in extreme habitats
b) Archaea have ether linkages in their cell membranes
c) Archaea have peptidoglycan cell walls
d) Archaea lack a nucleus
e) Archaea genomes are similar to those of eukaryote

Answer 11

b) Archaea have ether linkages in their cell membranes

Question 12

Organism ‘A’ converts glucose to carbon dioxide & organism ‘B’ converts the carbon dioxide to glucose. How are these two organisms best described?
a) A is an autotroph and B is a heterotroph
b) A is a lithotroph and B is photosynthetic
c) A is a heterotroph and B is an autotroph
d) A is a producer and B is a consumer
e) A is a saprophyte and B is a produce

Answer 12

c) A is a heterotroph and B is an autotroph

Question 13

Two techniques to isolate microbes in pure culture are:
a) Enriched media and selective media
b) Minimal media and differential media
c) Liquid broth and solid agar
d) Dilution streaking and spread plating
e) Gram stain and fluorescence microscopy

Answer 13

d) Dilution streaking and spread plating

Question 14

True or False:

The human eye can distinguish two objects 200 nm apart.

Answer 14

False

The human eye can only see as far asd 150-200 nm (likely hardly at 200).

Question 15

Which of the following statement are correct? The fluorophore commonly used to detect DNAusing fluorescence microscopy is:
a) FM4-64
b) GFP
c) DAPI
d) Phycocyanin
e) None of the above are correct.

Answer 15

c) DAPI

Question 16

You are a student in a research lab studying the adhesion of bacteriophages to bacterial cells. Yoursupervisor asks that you to provide them with high-resolution microscopy images proving theadhesion of a specific bacteriophage to E. coli. Which of the following techniques would you
recommend?
a) Light microscopy
b) Phase contrast microscopy
c) Fluorescence microscopy
d) Scanning electron microscopy.
e) All of the above.

Answer 16

d) Scanning electron microscopy.

SEM: 3D, high-resolution and capable of showing fine structural details

Question 17

Select the most accurate statement:

a) Light with a longer wavelength has higher energy and can therefore enable better resolution.
b) The numerical aperture of an objective lens is inversely correlated to its resolving power; the lower the NA, the higher the resolving power.
c) Glass slides and immersion oil used in microscopy have the same refractive index.
d) The longer wavelength of electrons than visible light enables the higher resolution of
electron microscopy.
e. Two of the above are correct.

Answer 17

c) Glass slides and immersion oil used in microscopy have the same refractive index.

Around 1.51