Bio 101 Final Exam
someone exposed to seasonal influenza in the past will have:
- memory B cells. - a risk for seasonal flu the next year. - still be at risk for h1n1 because prior exposure will not protect you from a different type of flu
The immune system occasionally malfunctions. Which of the following is an example of a result of a malfunction?
-allergies. -lupus. -multiple sclerosis
why are new strains of influenza identified each year?
-antigenic drift causes changes. -viruses reproduce rapidly and often make mistakes in their genetic sequence, resulting in a new strain of a virus. -viruses can swap genes with other viruses , creating a new virus.
viruses:
-are an infectious particle. -contain genetic material in the form of DNA and RNA. -have a capsid made of protein.
Why aren't human populations evolving to produce immune systems that are able to fight off MRSA and other "superbugs"
-because we may not have the mutations that would improve our immune systems. - Because the rate of human evolution is much slower than bacterial evolution
patterns of natural selection
-diversifying selection. -stabilizing selection. -directional selection.
Which of the following processes have been shown to contribute to the evolution of antibiotic resistance in S. aureus?
-gene swapping with other bacterial strains. -genetic mutations during S. aureus- reproduction.
all the following cells are important to our innate immunity
-natural killer cells. -macrophages. -neutrophils
3 components of the innate immune system and what they do
-skin prpovides a barrier to pathogen entry. - enzymes in tears and saliva digest components of pathogens. - phagocytes ingest and destroy pathogens.
Why is the evolution of antibiotic resistance in bacteria happening so quickly?
-the ability of overuse of antibiotics in humans. -because bacteria can reproduce so quickly. -because any use of antibiotics will select for resistant bacteria. -because overuse of antibiotics in livestock.
Which of the following factors may prevent most people from developing more than minor skin blemishes when they suffer from staph infection.
-their immune systems are preventing the infection from spreading. -helpful bacteria on their skin keep staph in check. -their skin is a physical barrier that keeps out the bacteria.
A bacterial cell that is resistant to a particular antibiotic may spend a large amount of energy producing the modified proteins that are needed for resistance. In such a case, what would be the effect on this cell's fitness if no antibiotic was present?
Its fitness would be lower than other strains that lack resistance because it is spending energy that the resistant strains can use for other purposes, such as reproduction.
If you examine a natural population of bacteria, it is common to find some antibiotic-sensitive and some antibiotic-resistant strains, even if the population has never been exposed to any antibiotic. Which of the following explanations could account for this situation?
The resistant strain developed as a mutation and has not negative effect on fitness
population
a group or organisms of the same species living together in the same geographic area
memory cell
a long-lived B or T cell that is produced during an immune response and that can 'remember' the pathogen
allergy
a misdirected immune response against environmental substances such as dust, pollen, and foods that causes discomfort in the form of physical symptoms.
autoimmune disease
a misdirected immune response in which the immune system attacks healthy cells.
histamine
a molecule released by damaged tissue and during allergic reactions
neutrophil
a phagocytic cell in the circulation that plays an important role in the inflammatory response.
macrophage
a phagocytic cell that resides in tissues and plays an important role in the inflammatory response
vaccine
a preparation of killed or weakened microorganisms or viruses that is administered to people or animals to generate an immune response,
adaptive immunity
a prospective response, mediated by lymphocytes, that confers long-lasting immunity against specific pathogens
antibody
a protein produced by B cells that bind to antigens and either neutralizes them or flags other cells to destroy pathogens
what is found in all viruses?
a protein shell
in the presence of penicillin, what happens to a resistant strain of S. aureus?
a resistant strain will not be effected by penicillin and will continue to grow.
in the presence of penicillin, what happens to a sensitive strain of S. aureus?
a sensitive strain of S. aureus will eventually burst (lyse) and die because of its weakened cell wall.
if a virus makes it past the body's first line of defenses, the next defense is ________
a series of cells designed to contain and destroy pathogens.
lymphocytes
a specialized white blood cell of the immune system. Lymphocytes are important in adaptive immunity.
antigen
a specific molecule (or part of a molecule) to which specific antibodies can bind, and against which and adaptive response is mounted.
immune system
a system of cells and tissues that acts to defend the body against foreign cells and infectious agents.
cytotoxic T cell
a type of T cell that destroys infected, cancerous, or foreign cells.
helper T cells
a type of T cell that helps activate B cells to produce antibodies.
binary fission
a type of asexual reproduction in which one parental cell divides into two
stabilizing solution
a type of natural selection in which organisms near the middle of the phenotypic range of variation are favored by the environment
diversifying selection
a type of natural selection in which organisms with phenotypes at both extremes of the phenotypic range are favored by the environment
directional selection
a type of natural selection in which organisms with phenotypes at one end of a spectrum are favored by the environment
natural cell killer
a type of white blood cell that acts during the innate immune response to fins and destroy virally infected cells and tumor cells.
phagocyte
a type of white blood cell that engulf and ingests damaged cells and pathogens
An organism's fitness depends on its ______.
ability to survive.
virus
an acellular infectious particle consisting of nucleic acid surrounded by a protein shell.
plasma cell
an activated B cell that divides rapidly and secretes an abundance of antibodies.
inflammation
an innate defense that is activated by infection or tissue damage; characterized by redness, heat, swelling, and pain.
Antibiotic-resistant strains of bacteria tend to first be found in hospitals. Which of the following factors explains why this is the case?
antibiotics are more likely to be present in hospitals, thus selecting resistant strains.
pandemics such as the Spanish Flu and the H1N1 virus are a result of_________
antigenic drift
interferon
antiviral proteins produced by virally infected cells that help protect adjacent cells from becoming infected.
binary fission is asexual. what does this mean? How could two daughter cells end up with different genomes at the end of one round of binary fission?
asexual reproduction involves only one parent. the parent passes on a copy of all its genetic material to its offspring. the two daughter cells that are the product of binary fission could be genetically different if a mutation occurred during replication of the parent genome before division. one copy could have a mutation and the other would not. each daughter cell would inherit one of the two different copies.
in what sense do bacteria evolve faster than other organisms
because bacteria divide rapidly, they have a short generation span. it does not take long for bacterial populations to accumulate many generations. as the chance of one or more mutations to arise with every generation, there is a wealth of genetic diversity for natural selection to act on.
Why do bacteria beta-lactam antibiotics affect sensitive bacterial cells but not eukaryotic cells?
beta-lactam antibiotics interfere with the synthesis of peptidoglycan-containing cell walls. humans do not have cell walls at all while white plant cells do, it is made of cellulose and peptidoglycan. Eukaryotic cells therefore do not have the structure that is the target of penicillin and other beta-lactam antibiotics.
How do beta-lactam antibiotics kill sensitive bacteria?
by destabilizing the cell wall
the immune system does not only fight pathogens, it also fights foreign cells such as those introduced during tissue transplantation. This type of immune reaction is called ________.
cell-mediated immunity
evolution
change in allele frequencies in a population over time
antigenic shift
changes in antigens that occur when viruses exchange genetic material with other strains.
antigenic drift
changes in viral antigens caused by genetic mutation during normal viral replication.
antibiotics
chemicals that either kill bacteria or slow their growth by interfering with the function of essential bacterial cell structures
An individual who carried staph but isn't sick is referred to as _______.
colonized.
natural selection
differential survival and reproduction of individuals in response to environmental pressure that leads to change in allele frequencies in a population over time
a sensitive S. aureus bacterium acquires a new gene that allows it to resist the effects of beta-lactam antibiotics. What might the protein encoded by that gene do?
digest beta-lactam antibiotics.
the evolution of antibiotic resistance is an example of
directional selection
what are the two major mechanisms by which bacterial populations generate genetic diversity?
gene transfer and mutation.
once you hsve contracted a virus such as the chicken pox, your body develops a _________ to the disease
immunity
what is the difference between an S. aureus colonization and an S aureus infection?
in colonization, the bacteria are growing on or in the body without causing disease. infections are associated with disease.
MRSA is most likely to be problematic if found
in the bloodstream
pathogens
infectious agents, including certain viruses, bacteria, fungi, and parasites. Many pathogens trigger an immune response.
why are those with influenza infections susceptible to bacterial pneumonia
influenza infections and the inflammatory responses initiated by influenza infections can damage the respiratory tract lining. influenza infections damage one of the first lines of response to other infections leaving them vulnerable to entry and infection of pathogen bacteria
the human body has two lines of defense against foreign pathogens. Immunity that is always present in our bodies is called________
innate immunity
the swelling associated with an injury is the result of _________
leaking blood vessels and increased immune system
What is the evolutionary process that causes antibiotic-resistant bacteria to increase and antibiotic-sensitive bacteria to decrease in an environment where antibiotics are present called?
natural selection
innate immunity
nonspecific defenses, such as physical and chemical barriers and specialized white blood cells that are present from birth and require little to no time or no time to become active
if we take the most fit bacterium from one environment- one in which the antibiotic amoxcicillin is abundant- for example, and place it in an environment in which a different antibiotic is abundant, will it retain its high degree of fitness?
not necessarily, fitness depends on the ability of an organism to survive and reproduce and it may not do this as well in a different environment.
four main features of innate immune function
physical barriers. antimicrobial chemicals. phagocytes. inflammation.
vaccination against a particular pathogen stimulates what kind of response
primary and secondary
complement proteins
proteins in the blood that help destroy pathogens by coating or puncturing them.,
a special protein called interferon helps the body fight viral infections. Interferon works by __________.
slowing the viral replication in neighboring cells and signaling immune cells to become active.
lymph nodes
small organs in the lymphatic system where B and T cells may encounter pathogens.
in humans, very large birth weight babies and very tiny babies do not survive as well as midrange babies. what kind of selection is acting on human birthweight?
stabilizing selection
what is the evolutionary meaning of the word 'fitness'
the ability of an individual to survive and reproduce in any given environment. individuals that are more fit leave more offspring and more of their alleles in the next generation relative to individuals that are less fit.
primary response
the adaptive response mounted the first time a particular antigen is encountered by the immune system
Why are viruses considered nonliving?
the cannot reproduce on their own
In strains of bacteria that are not resistant to beta-lactams, which of the following parts of the bacterial cells are disrupted by the antibiotic?
the cell walls
every year, thousands if people die from the influenza virus. Which of the following statements about the flu virus is false?
the flu can only kill immune-compromised individuals.
thymus
the organ in which T cells mature.
anti-hepatitis C antibodies present in a patient's blood indicate
the patient has been exposed to hepatitis C at least two weeks ago
Which of the following changes in a bacterial cell might reduce the effectiveness of beta-lactam antibiotics?
the presence of enzymes that are able to break down the antibiotic.
what is the environmental pressure in the case of antibiotic resistance?
the presence or absence of antibiotics in the environment.
adaptation
the process by which populations become better suited to their environment as a result of natural selection
secondary response
the rapid and strong response mounted when a particular antigen is encountered by the immune system subsequent to the first encounter.
fitness
the relative ability of an organism to survive and reproduce in a particular environment
immunity
the resistance to a given pathogen conferred by the activity of the immune system
lymphatic system
the system of vessels and organs that works with the immune system, allowing B and T cells to respond to pathogens.
humoral immunity
the type of adaptive immunity that fights free-floating pathogens in the blood and lymph fluid.
cell-mediated immunity
the type of adaptive immunity that rids the body of infected cancerous or foreign cells
once a virus enters a host cell, the host cell will most likely be destroyed as a result of:
the virus causing the host cell to rupture.
Why are individuals with a weakened immune system more likely to get sick?
their immune system cannot fight off the pathogens.
what do macrophages and neutrophils have in common?
they are both specialized in white blood cells and they are both phagocytes.
immature white cells that leave the bone marrow may become B lymphocytes. T cells are lymphocytes that
travel to the thymus and become T lymphocytes.
most adults have had a series of vaccinations throughout their life. The purpose of vaccinations is to
trigger the body to create antibodies to a specific person.
bacteriophage
viral infection that causes bacterial cell lysis.
Which is not true about viruses?
viruses cause the host cell to replicate
how do viruses replicated within humans?
viruses must enter their specific host cell in the human, thus infecting it. once they have entered the host cell, they use host cell resources and direct the host cell to replicate the virus.
B cells
white blood cells that mature in the bone marrow and produce antibodies during the adaptive immune response.
T cells
white blood cells that mature in the thymus and can destroy infected cells or stimulate B cells to produce antibodies, depending on the type of T cells.
can S. aureus be present in or on a person who has no evidence of an infection?
yes, S. aureus bacteria that are resistant to many antibiotics.
