Bio 215 Quiz 3 UPDATED Exam Questions
and CORRECT Answers
a virus is _____, not alive - CORRECT ANSWER - active
what has more treatment options, a virus or a bacterial infection? - CORRECT ANSWER -
bacterial infection
viruses are specific to their _____ - CORRECT ANSWER - host
Who discovered the first viruses in plants and how? - CORRECT ANSWER - Dmitrii
Iwanosky (1892) discovered that viruses could go through a bacterial filter which indicated that
they were smaller than bacteria
when a virus doesn't kill a plant, what does it do instead? - CORRECT ANSWER - it can
change its color or halt its development
What did Frederick William Twort and Felix d'Herelle discover? - CORRECT ANSWER -
that viruses could infect and kill bacteria (named bacteriophage, "devour bacteria")
what makes viruses unique? - CORRECT ANSWER - 1. they have no cellular structure
2. the virus has to infect the host cell to reproduce
what does a virus act like when not in a host? - CORRECT ANSWER - they act like
chemicals, since they are not alive they cannot die
viruses try to ____ the cell - CORRECT ANSWER - invade
what are the problems and solutions associated with antibiotics? - CORRECT ANSWER -
they are used to treat bacterial infections
,problem: we can develop resistance to them
solution: bacteriophages kill bacteria and they can serve as an alternate antibiotic
why can't bacteriophages kill all bacteria? - CORRECT ANSWER - certain bacteria are
resistant to certain bacteriophages
what are the two types of viruses? - CORRECT ANSWER - 1. naked virus
2. enveloped virus
naked virus - CORRECT ANSWER - *consists of nucleic acid and protein coat that
protects nucleic acid (made of capsid which is unit of capsomers)
*some have spikes to recognize the host cell (host cell receptors need to be complementary to
viral spikes, why only certain parts of body affected by certain viruses)
enveloped virus - CORRECT ANSWER - *lipid bilayer envelope surrounds virus
(sensitive to detergents and soaps that damage it)
*easy to disrupt the envelope by washing hands (the spikes are on envelope and damaged from
soap, so they cannot attach to host cell)
why are naked viruses more resilient? - CORRECT ANSWER - they cannot be deactivated
like enveloped viruses
viruses have nucleic acid of either ____ or ____ - CORRECT ANSWER - DNA, RNA
(cannot have both)
shapes of naked viruses (not applicable for enveloped) - CORRECT ANSWER - 1.
icosahedral: 12 sided (triangles)
Ex: adonovirus (common cold)
2. helical: genome inside helix, covered by protein coat (looks like unsharpened pencil)
Ex: tobacco mosaic virus (plant virus)
, 3. complex: head (no nucleic acid in head, "empty like ghost") tail, tail spikes and fibers
Ex: bacteriophage
how do we classify viruses? - CORRECT ANSWER - 1. DNA or RNA?
2. double or single stranded?
3. enveloped or naked?
what are virus names based on? - CORRECT ANSWER - appearance, where it was found,
etc (no particular pattern)
what are the routes for transmission of viruses? - CORRECT ANSWER - 1. feucal oral
route: like diarrhea
2. respiratory route: like flu or COVID
3. zootonic route: animal to human like rabies
4. sexually transmitted: like HIV
what are the three different kinds of phages based on relationship with host? - CORRECT
ANSWER - 1. lytic phages (kill bacteria)
2. temperate phages (may or may not kill bacteria)
3. filamentous phages (do not kill bacteria)
What is the five step process of lytic phage infections? - CORRECT ANSWER - 1.
attachment (phage attaches to receptors on host cell wall)
2. genome entry (phage DNA injected into host cell when tail of bacteriophage penetrates host
cell wall, peptidoglycan of cell wall degraded by lysozyme so phage can infect DNA, phage coat
left outside cell)
3. synthesis (phage genome from phage head transcribed to mRNA then translated to phage
proteins, phage DNA replicated to make more copies of phage particles)
4. assembly (phage components assembled into mature virions)
and CORRECT Answers
a virus is _____, not alive - CORRECT ANSWER - active
what has more treatment options, a virus or a bacterial infection? - CORRECT ANSWER -
bacterial infection
viruses are specific to their _____ - CORRECT ANSWER - host
Who discovered the first viruses in plants and how? - CORRECT ANSWER - Dmitrii
Iwanosky (1892) discovered that viruses could go through a bacterial filter which indicated that
they were smaller than bacteria
when a virus doesn't kill a plant, what does it do instead? - CORRECT ANSWER - it can
change its color or halt its development
What did Frederick William Twort and Felix d'Herelle discover? - CORRECT ANSWER -
that viruses could infect and kill bacteria (named bacteriophage, "devour bacteria")
what makes viruses unique? - CORRECT ANSWER - 1. they have no cellular structure
2. the virus has to infect the host cell to reproduce
what does a virus act like when not in a host? - CORRECT ANSWER - they act like
chemicals, since they are not alive they cannot die
viruses try to ____ the cell - CORRECT ANSWER - invade
what are the problems and solutions associated with antibiotics? - CORRECT ANSWER -
they are used to treat bacterial infections
,problem: we can develop resistance to them
solution: bacteriophages kill bacteria and they can serve as an alternate antibiotic
why can't bacteriophages kill all bacteria? - CORRECT ANSWER - certain bacteria are
resistant to certain bacteriophages
what are the two types of viruses? - CORRECT ANSWER - 1. naked virus
2. enveloped virus
naked virus - CORRECT ANSWER - *consists of nucleic acid and protein coat that
protects nucleic acid (made of capsid which is unit of capsomers)
*some have spikes to recognize the host cell (host cell receptors need to be complementary to
viral spikes, why only certain parts of body affected by certain viruses)
enveloped virus - CORRECT ANSWER - *lipid bilayer envelope surrounds virus
(sensitive to detergents and soaps that damage it)
*easy to disrupt the envelope by washing hands (the spikes are on envelope and damaged from
soap, so they cannot attach to host cell)
why are naked viruses more resilient? - CORRECT ANSWER - they cannot be deactivated
like enveloped viruses
viruses have nucleic acid of either ____ or ____ - CORRECT ANSWER - DNA, RNA
(cannot have both)
shapes of naked viruses (not applicable for enveloped) - CORRECT ANSWER - 1.
icosahedral: 12 sided (triangles)
Ex: adonovirus (common cold)
2. helical: genome inside helix, covered by protein coat (looks like unsharpened pencil)
Ex: tobacco mosaic virus (plant virus)
, 3. complex: head (no nucleic acid in head, "empty like ghost") tail, tail spikes and fibers
Ex: bacteriophage
how do we classify viruses? - CORRECT ANSWER - 1. DNA or RNA?
2. double or single stranded?
3. enveloped or naked?
what are virus names based on? - CORRECT ANSWER - appearance, where it was found,
etc (no particular pattern)
what are the routes for transmission of viruses? - CORRECT ANSWER - 1. feucal oral
route: like diarrhea
2. respiratory route: like flu or COVID
3. zootonic route: animal to human like rabies
4. sexually transmitted: like HIV
what are the three different kinds of phages based on relationship with host? - CORRECT
ANSWER - 1. lytic phages (kill bacteria)
2. temperate phages (may or may not kill bacteria)
3. filamentous phages (do not kill bacteria)
What is the five step process of lytic phage infections? - CORRECT ANSWER - 1.
attachment (phage attaches to receptors on host cell wall)
2. genome entry (phage DNA injected into host cell when tail of bacteriophage penetrates host
cell wall, peptidoglycan of cell wall degraded by lysozyme so phage can infect DNA, phage coat
left outside cell)
3. synthesis (phage genome from phage head transcribed to mRNA then translated to phage
proteins, phage DNA replicated to make more copies of phage particles)
4. assembly (phage components assembled into mature virions)
