How do we study microbes? As microbiologists, when we conduct scientific inquiry, we think in terms of: What is the evidence? How was it obtained? Scientific method is a process for experimentation that is used to conduct scientific inquiry. We seek experimental evidence that tests what we think we...
MCB 100 Exam 1 Questions and 100%
Correct Answers
How do we study microbes? ✅As microbiologists, when we conduct scientific inquiry,
we think in terms of: What is the evidence? How was it obtained?
Scientific method is a process for experimentation that is used to conduct scientific
inquiry. We seek experimental evidence that tests what we think we know (a hypothesis
or model).
What is the purpose of the scientific method? ✅To minimize bias/error in experiments
Which of these inventions was critical to the establishment of the field of microbiology?
✅Microscope
Antonie van Leeuwenhoek (1632-1723) ✅first observed microbes under a microscope
(1676)
Germ Theory ✅proposes that microorganisms are the cause of many diseases
Girolamo Fracastoro (1478-1553) ✅proposed in 1545 that epidemic diseases were
caused by transferable tiny particles or "tinder" that could transmit infection by contact.
Agostino Bassi (1772-1856) ✅discovered in 1807 that muscardine disease of
silkworms was caused by living parasitic organism (fungus, Beauveria bassiana) and in
1884 proposed that human diseases (syphilis, plague) were also caused by living
microorganisms.
Friedrich Henle (1809-1885) ✅developed the concepts of contagium vivum and
contagium animatum in his essay "Von den Miasmen und Kontagien" in 1840 (miasma
= "bad air") - early germ theory that living organisms caused infectious diseases.
Ignaz Semmelweis (1818- 1865) ✅made the connection between lack of hand
washing and childbirth (puerperal) fever in 1847. Making doctors wash hands with
chlorinated lime water reduced mortality from childbirth fever from 18% to 2% at his
hospital.
John Snow (Father of Epidemiology) ✅traced the source of a cholera outbreak in
London in 1854 to contaminated water obtained from a particular well, which was at the
geographical center of the outbreak.
Louis Pasteur ✅conducted the first experiments demonstrating that fermentation and
growth of microbes in nutrient broth did not proceed by spontaneous generation or by
, miasma (bad air) - two prevailing theories at the time. Importantly, he was able to
convince most of Europe at the time. His research showed that microbes caused beer,
wine and milk to spoil and he invented the process of pasteurization in 1862.
Which of the following statements is false?
a. There are about 10 million (107) microbes on earth for each star in the universe.
b. On average, there is one virus particle for every bacterial cell on earth.
c. On average, the human body plays host to about two bacterial cells for each one of
its own.
Microbial cells have been in existence for at least 3.5 billion years.
d. Cyanobacteria originated approximately 3 billion years ago? ✅b. On average, there
is one virus particle for every bacterial cell on earth.
What is spontaneous generation? ✅developed to explain how life seems to come from
nonliving matter. An example would be the production of maggots from decaying meat.
How did Francesco Redi attempt to disprove the theory of spontaneous generation?
✅He performed a series of experiments involving decaying meat and maggots. Redi
showed that maggots do not spontaneously arise from nonliving meat, but instead come
from flies depositing eggs.
Which scientist definitively ended the debate over spontaneous generation? ✅Pasteur
Some critics of Spallanzani's experiments thought that the reason sealed flasks were
unable to spontaneously generate microorganisms was that there was not enough air
present to support life. How did Louis Pasteur respond to this claim? ✅He modified the
experiment to include air as treatment
Where did microbes end up in Pasteur's experiment? ✅In the S-shaped curve of the
flask
What is the correct order for the application of Koch's postulates?
I. Inoculate suspect agent into test subject and observe that subject develops disease of
interest.
II. Isolate and culture suspect agent in the laboratory.
III. Find suspect agent is every case of disease of interest but not in healthy hosts.
IV. Recover and isolate suspect agent from test subject. ✅III, II, I, IV
Some scientists are studying a newly discovered microbe and determine that it consists
of a single cell, lacking a nucleus. This organism could be ✅a bacterium. (prokaryotic
and unicellular)
Which of the following always reproduce inside a host cell? ✅viruses (obligate
intracellular parasite)
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