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Question
Knowing the concentration of microorganisms in a sample is often an important consideration for environmental, industrial, and medical microbiologists, yet a microscope is sometimes not used to accomplish this task. Explain five major limitations to using a light microscope to directly count microorganisms.Answer
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Related questions
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The immune response is as important as or even more important than antibiotics in the elimination of Bordetella pertussis from the body.
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Salt in mannitol salt agar inhibits the growth of Staphylococcus aureus.
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The inflammatory response to Corynebacterium diphtheriae infection results in the production of a lesion called a(n)
A) pseudomembrane.
B) chancre.
C) lesion.
D) pustule.
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Pus formation in skin lesions caused by Staphylococcus aureus infections is in part due to production of
A) coagulase.
B) hemolysins.
C) leukocidin.
D) catalase.
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The most common infectious disease(s) is/are
A) gonorrhea.
B) influenza.
C) hepatitis.
D) colds.
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Which disease causes over 1.6 million deaths per year worldwide, which is approximately 11% of all deaths related to infectious diseases?
A) diphtheria
B) whooping cough
C) pneumococcal pneumonia
D) tuberculosis
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Which of the following is the causal agent of gastric ulcers?
A) Staphylococcus aureus
B) Escherichia coli O157:H7
C) Helicobacter pylori
D) Vibrio cholerae
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Which of the following statements about chlamydial infections is TRUE?
A) Chlamydial diseases are not reportable diseases.
B) Chlamydial diseases are less prevalent than gonorrhea.
C) Chlamydial diseases can lead to acute complications.
D) All of the statements are true.
Q:
The Spanish flu of 1918 was caused by an ________ influenza virus.
A) H2N1
B) H5N1
C) H1N1
D) H2N2
Q:
Diseases can be controlled through immunization even if the percentage of the population that is immunized is less than 100% because
A) vectors can be controlled through other means.
B) most diseases lack reservoirs.
C) of herd immunity.
D) vehicles can be sterilized.
Q:
In just over a decade of efforts, the World Health Organization (WHO) eradicated smallpox by using worldwide
A) education campaigns.
B) destruction of infected domestic animals.
C) education campaigns and destruction of infected domestic animals.
D) vaccination programs.
Q:
In 2003, the majority of AIDS deaths occurred in
A) South America.
B) North America.
C) Europe.
D) Sub-Saharan Africa.
Q:
The study of the occurrence, distribution, and determinants of health and disease in a population is the field of
A) microbiology.
B) immunology.
C) epidemiology.
D) virology.
Q:
Filoviruses (such as Ebola virus) that cause severe hemorrhagic fevers generally have high ________ but low ________.
A) incidence / prevalence
B) prevalence / mortality
C) mortality / morbidity
D) morbidity / mortality
Q:
Cholera is an example of a pandemic disease that
A) has multiple wild animal reservoirs and is thus difficult to eradicate.
B) spreads from a common source and could be controlled with adequate clean water and waste sanitation measures.
C) is spread through direct contact and has only a human reservoir.
D) has recently emerged due to overcrowding in urban centers.
Q:
Influenza pandemics occur cyclically because
A) less than 100% of the population is immunized.
B) new strains emerge due to reassortment between bird, swine, and human variants.
C) the vector is seasonal.
D) there are environmental reservoirs that release the virus during particular seasons.
Q:
Which body site is preferentially infected by foodborne pathogens?
A) gastrointestinal tract
B) respiratory tract
C) cerebrospinal fluid
D) liver
Q:
Potential candidates for biological warfare
A) are generally gram-negative rather than gram-positive.
B) can be virtually any pathogenic bacterium or virus.
C) are eukaryotic rather than prokaryotic.
D) must be genetically engineered to be effective.
Q:
Why are public health officials concerned about smallpox being used as a biological weapon? Give several reasons in your answer.
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Rodents have been associated with numerous severe epidemics in the past, prompting microbiologist Hans Zinsser in the 1930s to write a book, Rats, Lice, and History, in which he documented the important role of rodents in epidemics. Discuss why rodent control is still desirable, even in an age when it is perceived that the "magic bullets" of chemotherapy and immunization to control infectious disease are readily available.
Q:
The arrangement of Class II MHC proteins in pairs or trimers enhances their stability.
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The cytoplasmic domains of immunoglobulins and TCRs have cytoplasmic tyrosines that can be phosphorylated.
Q:
In B cell selection and tolerance, if no signal is generated from ________ cells, the B cells remain unresponsive.
A) TC
B) TH
C) B7
D) CD28
Q:
________ ensures that each B cell produces only one immunoglobulin.
A) Self-activation
B) Allelic exclusion
C) MHC interaction
D) Clonal deletion
Q:
The invariant amino acids in each peptide motif bound by MHC proteins are called
A) anchor residues.
B) MHC peptides.
C) antigen-binding immunoglobulins.
D) TCR peptides.
Q:
The major histocompatibility complex is also called the
A) human leukocyte antigen (HLA).
B) T cell receptor.
C) toll-like receptor complex.
D) T cell receptor or toll-like receptor.
Q:
Interaction of a PAMP with a TLR triggers transmembrane signal transduction and subsequent
A) clonal expansion.
B) antibody production.
C) complement protein activation.
D) phagocytosis and inflammation.
Q:
Which of the following is involved in B cell selection and tolerance?
A) clonal anergy
B) clonal deletion
C) clonal anergy and deletion
D) allelic exclusion
Q:
Clonal anergy is a state of
A) antibody production.
B) high energy.
C) unresponsiveness.
D) high energy and antibody production.
Q:
An individual usually expresses ________ structurally distinct allele(s) that encode class I MHC proteins.
A) one
B) two
C) four
D) six