BIOL 251 Final Exam Review (2025)

Which of the following is TRUE regarding bacterial strains?

A) They are similar bacteria 

B) They have many characteristics in common but belong to different species 

C) They are more distantly related to others that members of a species are to each other 

D) They are informal groupings of bacteria used solely for medical purposes 

E) They are closely related isolates or subtypes within a bacterial species that do not share all characteristics 

E) They are closely related isolates or subtypes within a bacterial species that do not share all characteristics

The Gram stain is useful for which of the following reasons?

 A) Provides useful information for identification of a bacterial species; but does not provide enough information on its own for identification 

 B) Can be used to distinguish between different strains of bacteria 

 C) Provides enough information for determining what growth media to select for bacterial growth 

 D) Provides enough information to identify a bacterial species 

 E) It is helpful in determining the bacterial species nutritional requirements 

A) Provides useful information for identification of a bacterial species; but does not provide enough information on its own for identification 

Prokaryotes are found in which of the following domain(s)?

A)  Archaea domain only 

B)  Bacteria domain only 

C)  All three domains 

D) Archaea and Eukarya domains only 

E)  Archaea and Bacteria domains only 

E)  Archaea and Bacteria domains only 

Which of the following is TRUE of ribosomes?

A)  Bacterial ribosomes are 80S and eukaryotic ribosomes are 70S 

B)  Bacteria ribosomes cannot be distinguished from eukaryotic ribosomes 

C)  Bacterial ribosomes are 70S and eukaryotic ribosomes are twice are big 

D)  Bacteria ribosomes and eukaryotic ribosomes are structurally identical 

E)  Bacterial ribosomes and eukaryotic ribosomes are structurally different 

E)  Bacterial ribosomes and eukaryotic ribosomes are structurally different 

Which of the following cannot be classified as either gram positive or gram negative based on the gram staining protocol?

 A) Mycoplasma 

 B) Streptococcus 

 C) Clostridium 

 D) Bacillus 

 E) Pseudomonas 

 A) Mycoplasma 

Which of the following is NOT a characteristic of a virus?

A)  is an acellular infectious agent 

B)  genome is surrounded by a protein capsid 

C)  genome consists of DNA or RNA 

D)  it replicates independently 

E)  requires a host cell for replication 

D)  it replicates independently 

Which statement is TRUE regarding relative sizes?

A)  Viruses are smaller than bacteria and have never been visualized 

B)  Viruses are larger than most bacterial cells and can only be visualized using an electron microscope 

C)  Bacteria are larger than viruses can only be visualized using an electron microscope 

D)  Viruses are smaller than bacteria and cannot be visualized with light microscopes 

E)  Viruses and bacteria are the same size and both are easily visualized with a light microscope 

D)  Viruses are smaller than bacteria and cannot be visualized with light microscopes 

Bacteria that grow faster in the presence of oxygen, and more slowly in the absence of oxygen are classified as

 A) obligate anaerobes 

 B) aerotolerant anaerobes 

 C) obligate aerobes 

D)  microaerophiles 

E)  facultative anaerobes 

E)  facultative anaerobes 

Bacteria that thrive in the human body might be classified as

A)  hyperthermophiles and alkaliphiles 

B)  mesophiles and neutrophiles 

C)  psychrophiles and neutrophiles 

D)  thermophiles and acidophiles 

E)  mesophiles and acidophiles

B)  mesophiles and neutrophiles 

A mechanisms of horizontal gene transfer that involves bacteriophage is called

A)  transformation 

B)  transduction 

C)  conjugation 

D)  transpiration 

E)  both transformation and transduction involved bacteriophage 

B)  transduction 

Which of the following is NOT a characteristic of plasmids

A)  often have antibiotic resistance genes 

B)  extrachromosomal DNA element 

C)  may be transferred horizontally 

D)  double stranded DNA 

E)  DNA element transferred by bacteriophage 

E)  DNA element transferred by bacteriophage 

Which of the following is an INCORRECT pairing?

A)  Membrane filtration: sterilizes heat sensitive liquids 

B)  Pasteurization: sterilization method 

C)  Boiling: kills vegetative bacteria 

D)  Ethylene oxide: gaseous sterilant 

E)  Autoclaving: sterilization method 

B)  Pasteurization: sterilization method 

In a clinical settings and laboratories, what is the purpose of aseptic technique??

A)  detect contaminants 

B)  to prevent contamination of living tissue 

C)  to maintain sterility of critical items 

D)  to protect fomites 

E)  enhance microbial growth 

B)  to prevent contamination of living tissue 

Which of the following is a semisynthetic antibiotic?

A)  Neomycin 

B)  Streptomycin 

C)  Ampicillin 

D)  Actinomycin 

E)  Penicillin 

C)  Ampicillin 

What is the target of aminoglycosides?

  plasma membrane 

A)  cell wall 

B)  folic acid biosynthesis 

C)  80S ribosomes 

D)  70S ribosomes 

D)  70S ribosomes 

What is endotoxin?

A)  a toxin secreted by gram negative bacteria 

B)  the same thing as a superantigen  

C)  LPS in the gram positive cell wall 

D)  LPS in the gram negative cell wall 

E)  a toxin secreted by gram positive and gram negative bacteria 

D)  LPS in the gram negative cell wall 

For an A-B toxin, what is responsible for recognizing and attaching to host cells?

A)  both the A and B subunits 

B)  B subunit 

C)  either A or B subunit, it depends on the toxin 

D)  neither, the toxin binds nonspecifically 

E)  A subunit 

B)  B subunit 

Which are NOT phagocytic cells?

A)  dendritic cells 

B)  neutrophils 

C)  monocytes 

D)  basophils 

E)  macrophages 

D)  basophils 

A cell of that has been infected with an intracellular pathogen, such as a virus, will be targeted for destruction by which type of lymphocyte ?

A)  CD8+ cytotoxic cell 

B)  macrophage 

C)  B cell 

D)  plasma cell 

E)  CD4+ helper T cell

A)  CD8+ cytotoxic cell 

During secondary exposure to an antigen

A)  only IgM is produced, but in greater quantity compared to the primary response 

B)  IgG is produced quicker than in the primary response, and the amount produced in the same 

C)  IgG is produced more quickly and in larger amounts compared to the primary response 

D)  IgM is produced in larger quantities compared to the primary response 

E)  More IgG is produced than in the primary response, but it takes longer

C)  IgG is produced more quickly and in larger amounts compared to the primary response