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Biol 240 - UW - Final Exam 2026 |
Actual Questions And Answers
Viruses Entering Plant Cells - correct-answer -Often depends on damage to plant
tissues to open a spot in the cell wall (insects feeding on plants, wind damage,
hail/rain damage, fire damage, human-induced damage). These do not require
receptors, they just require holes in the cellulose cell walls that the viruses can fall
through
Viruses Entering Bacterial Cells - correct-answer -Like a hypodermic syringe,
where DNA injected directly into the cell. These viruses have tail fibers that attach
to receptors on the outer membrane of bacteria. The receptors are just normal
membrane proteins that the tail fibers adapt to (so that they can latch on)
Virus Tail Fibers - correct-answer -When bound, a conformational change in tail
fibers brings the base of the virus in contact with the host cell surface.
Rearrangement of tail proteins allows inner core tube proteins to extend down
into the cell wall. Contact with the plasma membrane initiates transfer of DNA
through a pore formed in the lipid bilayer of the bateria
Bacteriophage Replication - correct-answer -Either lytic or lysogenic
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Lytic Cycle - correct-answer -Viruses enter, replicate, and lyse host cell
Lysogenic cycle ("temperate phage") - correct-answer -Phage integrate their
genome into host (i.e., "lysogen") cell's genome, becoming a "prophage".
Prophage genome is replicated along with the host cell's until... stress... then back
to lytic phase.
Temperate Phage versus Lytic Phage - correct-answer -Temperate phage can be
both lytic or exist as a prophage ("lysogeny"). Lytic phage are lytic.
Coevolution Hypothesis - correct-answer -Viruses originated about the same time
as other microbes and have been coevolving with them.
Regressive Hypothesis - correct-answer -Viruses are previously alive organisms
that have evolutionarily regressed into host-dependent particles.
Progressive Hypothesis - correct-answer -Viruses originated from genetic material
that gained the ability to replicate and be transmitted semi-autonomously
,3|Page
Cultivating Bacteriophage - correct-answer -Much trickier to work with than
bacteria (very small, and they need their specific host). Uses agar plating to create
plaques
Cultivating Animal Viruses - correct-answer -Tissue culture of host cells used to
grow targets for the viruses (or in embryonated chicken or duck eggs for <$$$).
Cultures must be kept sterile and bacteria-free methods have only been in place
since the 1950s. Modern virology couldn't exist without these tools, many
developed from first human cell line, known as HeLa cells
Viral Purification - correct-answer -Usually begins with simple filtration to remove
large cells and cellular debris. Viruses then purified and concentrated with
centrifugation
Differential Centrifugation - correct-answer -Centrifuging at consecutively higher
speeds and removing sunken pellets until all we have left is pellets of virus
Gradient Centrifugation - correct-answer -Depends on different densities of viral
components and particles. Particles sink of float in the tubes in areas of
decreasing concentrations of sucrose
, 4|Page
Viral Quantification - correct-answer -Not easy of straight forward. Usually
measured as a titer, or concentration of a virus preparation. Methods include
direct count, hemagglutination assay, plaque assay, and endpoint assays
Direct Count - correct-answer -Electron microscope used to visualize a known
volume of material. Viruses within it counted and scaled up to determine titer.
Requires an expensive, specialized microscope. Doesn't differentiate between
infectious and non-infectious viral particles
What unique feature would you predict that viruses of gram positive bacteria
would use for attachment? - correct-answer -Techtoic acids
Which is not a way that bacteria condense their DNA? - correct-answer -Histones
What form of Eukaryotic cells did Robert Hooke see through his microscope? -
correct-answer -Fungi
What is the mold that appears on bread? - correct-answer -Zygomycota
Biol 240 - UW - Final Exam 2026 |
Actual Questions And Answers
Viruses Entering Plant Cells - correct-answer -Often depends on damage to plant
tissues to open a spot in the cell wall (insects feeding on plants, wind damage,
hail/rain damage, fire damage, human-induced damage). These do not require
receptors, they just require holes in the cellulose cell walls that the viruses can fall
through
Viruses Entering Bacterial Cells - correct-answer -Like a hypodermic syringe,
where DNA injected directly into the cell. These viruses have tail fibers that attach
to receptors on the outer membrane of bacteria. The receptors are just normal
membrane proteins that the tail fibers adapt to (so that they can latch on)
Virus Tail Fibers - correct-answer -When bound, a conformational change in tail
fibers brings the base of the virus in contact with the host cell surface.
Rearrangement of tail proteins allows inner core tube proteins to extend down
into the cell wall. Contact with the plasma membrane initiates transfer of DNA
through a pore formed in the lipid bilayer of the bateria
Bacteriophage Replication - correct-answer -Either lytic or lysogenic
,2|Page
Lytic Cycle - correct-answer -Viruses enter, replicate, and lyse host cell
Lysogenic cycle ("temperate phage") - correct-answer -Phage integrate their
genome into host (i.e., "lysogen") cell's genome, becoming a "prophage".
Prophage genome is replicated along with the host cell's until... stress... then back
to lytic phase.
Temperate Phage versus Lytic Phage - correct-answer -Temperate phage can be
both lytic or exist as a prophage ("lysogeny"). Lytic phage are lytic.
Coevolution Hypothesis - correct-answer -Viruses originated about the same time
as other microbes and have been coevolving with them.
Regressive Hypothesis - correct-answer -Viruses are previously alive organisms
that have evolutionarily regressed into host-dependent particles.
Progressive Hypothesis - correct-answer -Viruses originated from genetic material
that gained the ability to replicate and be transmitted semi-autonomously
,3|Page
Cultivating Bacteriophage - correct-answer -Much trickier to work with than
bacteria (very small, and they need their specific host). Uses agar plating to create
plaques
Cultivating Animal Viruses - correct-answer -Tissue culture of host cells used to
grow targets for the viruses (or in embryonated chicken or duck eggs for <$$$).
Cultures must be kept sterile and bacteria-free methods have only been in place
since the 1950s. Modern virology couldn't exist without these tools, many
developed from first human cell line, known as HeLa cells
Viral Purification - correct-answer -Usually begins with simple filtration to remove
large cells and cellular debris. Viruses then purified and concentrated with
centrifugation
Differential Centrifugation - correct-answer -Centrifuging at consecutively higher
speeds and removing sunken pellets until all we have left is pellets of virus
Gradient Centrifugation - correct-answer -Depends on different densities of viral
components and particles. Particles sink of float in the tubes in areas of
decreasing concentrations of sucrose
, 4|Page
Viral Quantification - correct-answer -Not easy of straight forward. Usually
measured as a titer, or concentration of a virus preparation. Methods include
direct count, hemagglutination assay, plaque assay, and endpoint assays
Direct Count - correct-answer -Electron microscope used to visualize a known
volume of material. Viruses within it counted and scaled up to determine titer.
Requires an expensive, specialized microscope. Doesn't differentiate between
infectious and non-infectious viral particles
What unique feature would you predict that viruses of gram positive bacteria
would use for attachment? - correct-answer -Techtoic acids
Which is not a way that bacteria condense their DNA? - correct-answer -Histones
What form of Eukaryotic cells did Robert Hooke see through his microscope? -
correct-answer -Fungi
What is the mold that appears on bread? - correct-answer -Zygomycota
