BIOS 242 ACTUAL 2026 VIEW AHEAD
QUESTIONS ANSWERS
◉ archaea. Answer: unicellular prokaryotic microbes; none have
been identified as human pathogens; cell walls do not contain
peptidoglycan, but are often composed of a similar subsistence
called pseudopeptidoglycan
◉ bacteria. Answer: most are harmless or helpful, but some are
pathogens; prokaryotic due to genetic material (DNA) but is not
housed within a true nucleus; most have cell walls containing
peptidoglycan
◉ eukarya. Answer: eukaryotes
◉ scientific nomenclature. Answer: species is capitalized, genus is
lowercase (e.g., Homo sapiens)
◉ prokaryotic cell structures. Answer: no nucleus (nucleoid); no
membrane bound organelles; single chromosome; simple flagella;
circular DNA; smaller and unicellular; smaller ribosomes
◉ eukaryotic cell structures. Answer: nucleus; membrane bound
organelles (cell wall); chromosomes in pairs; complex flagella;
,complex DNA; larger and multicellular; larger ribosomes;
*mitochondria
◉ light microscope. Answer: microscope that uses a beam of light
passing through one or more lenses to magnify an object
◉ brightfield microscope. Answer: most common; compound
microscope using 2 lenses that produce a dark image on a bright
background
◉ chromophores. Answer: pigments that absorb and reflect
particular wavelengths of light; different colors can behave
differently when they interact with chromophores
◉ darkfield microscope. Answer: brightfield microscope that has a
small but significant modification to the condenser
◉ light microscope: phase-contrast. Answer: use refraction and
interference caused by structures in a specimen to create high-
contrast, high-resolution images without staining; oldest an simplest
◉ light microscope: differential interference contrast (DIC). Answer:
2 beams of light are created in which the direction of wave
movement (polarization) differs
, ◉ light microscope: fluorescence. Answer: uses fluorescent
chromophores (fluorochromes) capable of absorbing energy from a
light source and them emitting this energy as visible light
◉ immunofluorescence. Answer: used to identify certain disease-
causing microbes by observing whether antibodies bind to them
◉ immunofluorescence: direct immunofluorescence assay (DFA).
Answer: specific antibodies are stained with a fluorochrome- if the
specimen contains the targeted pathogen, one can observe the
antibodies binding to the pathogen under the fluorescent
microscope (called a primary antibody stain because the stained
antibodies directly attach to the pathogen
◉ immunofluorescence: indirect immunofluorescence assay (IFA).
Answer: secondary antibodies are stained with a fluorochrome
rather than primary antibodies- secondary antibodies do not
directly attach to the pathogen, but they do bind to primary
antibodies (secondary antibodies are attached indirectly)
◉ light microscope: confocal microscope. Answer: uses a laser to
scan multiple z-planes successively, producing numerous 2D, high-
contrast images at various depths that can be constructed into 3D
images by a computer, making this useful for examining thick
specimens (like biofilms)
QUESTIONS ANSWERS
◉ archaea. Answer: unicellular prokaryotic microbes; none have
been identified as human pathogens; cell walls do not contain
peptidoglycan, but are often composed of a similar subsistence
called pseudopeptidoglycan
◉ bacteria. Answer: most are harmless or helpful, but some are
pathogens; prokaryotic due to genetic material (DNA) but is not
housed within a true nucleus; most have cell walls containing
peptidoglycan
◉ eukarya. Answer: eukaryotes
◉ scientific nomenclature. Answer: species is capitalized, genus is
lowercase (e.g., Homo sapiens)
◉ prokaryotic cell structures. Answer: no nucleus (nucleoid); no
membrane bound organelles; single chromosome; simple flagella;
circular DNA; smaller and unicellular; smaller ribosomes
◉ eukaryotic cell structures. Answer: nucleus; membrane bound
organelles (cell wall); chromosomes in pairs; complex flagella;
,complex DNA; larger and multicellular; larger ribosomes;
*mitochondria
◉ light microscope. Answer: microscope that uses a beam of light
passing through one or more lenses to magnify an object
◉ brightfield microscope. Answer: most common; compound
microscope using 2 lenses that produce a dark image on a bright
background
◉ chromophores. Answer: pigments that absorb and reflect
particular wavelengths of light; different colors can behave
differently when they interact with chromophores
◉ darkfield microscope. Answer: brightfield microscope that has a
small but significant modification to the condenser
◉ light microscope: phase-contrast. Answer: use refraction and
interference caused by structures in a specimen to create high-
contrast, high-resolution images without staining; oldest an simplest
◉ light microscope: differential interference contrast (DIC). Answer:
2 beams of light are created in which the direction of wave
movement (polarization) differs
, ◉ light microscope: fluorescence. Answer: uses fluorescent
chromophores (fluorochromes) capable of absorbing energy from a
light source and them emitting this energy as visible light
◉ immunofluorescence. Answer: used to identify certain disease-
causing microbes by observing whether antibodies bind to them
◉ immunofluorescence: direct immunofluorescence assay (DFA).
Answer: specific antibodies are stained with a fluorochrome- if the
specimen contains the targeted pathogen, one can observe the
antibodies binding to the pathogen under the fluorescent
microscope (called a primary antibody stain because the stained
antibodies directly attach to the pathogen
◉ immunofluorescence: indirect immunofluorescence assay (IFA).
Answer: secondary antibodies are stained with a fluorochrome
rather than primary antibodies- secondary antibodies do not
directly attach to the pathogen, but they do bind to primary
antibodies (secondary antibodies are attached indirectly)
◉ light microscope: confocal microscope. Answer: uses a laser to
scan multiple z-planes successively, producing numerous 2D, high-
contrast images at various depths that can be constructed into 3D
images by a computer, making this useful for examining thick
specimens (like biofilms)
