Sample Test Based on Foundations In Microbiology 11Th
Edition By Kathleen Park Talaro – Test Bank
Sample Test
Answers to Writing to Learn Questions/Writing Challenge Questions
CHAPTER 1
1. What does it mean to say microbes are ubiquitous?
From the Latin ubique, meaning “everywhere”, it is a succinct way of saying that
microbes exist everywhere throughout the natural world, even areas with extreme
conditions. Other ways to express this idea are the terms universally widespread and
constantly present. The only environments that are microbe free have probably been
artificially sterilized by humans.
2. What is meant by diversity?
The term diversity is used to denote the immense variety in different types of
organisms, with regard to such characteristics as appearance, life style, and
distribution. Although about 1.2 million different species of organisms have been
discovered and named, this is only a small fraction of the true diversity present over
the entire planet and its millions of habitats. The case study emphasizes that we are
still at the early stages in exploring the richness of life (especially of the microbial
type) that is hidden and largely unknown because of small size and inaccessiblity.
3. Most important events and discoveries:
Many hundreds of separate scientists and labs contributed to the rise of
microbiology during its early history. Tools such as the microscope allowed direct
observation of samples and their microbial contents. Microbes were subsequently
seen as discrete entities that could be observed, described, and documented much
,like larger organisms. Development of laboratory techniques for culturing microbes
using sterile techniques allowed macroscopic handling and control of microbes so
they could be studied and understood in greater depth.
Application of the scientific method and experiments to standardize the
requirements for fact-based inquiries were very important. The abandonment of the
spontaneous generation theory was especially significant because it departed from
superstition and prejudice in favor of the scientific method. The institution of the
germ theory of disease and the development of aseptic techniques were an essential
contribution to medical aspects of microbiology. The knowledge that microbes
cause food spoilage and disease led to early attempts to control microbes using heat
and other methods.
4. Use of the scientific method:
A hypothesis is a statement put forth by an investigator that purports to explain a
phenomenon based upon a collection of observations, tests, and other objective
criteria. It can be tested experimentally. A theory is a statement of confidence that
scientifically-based observations provide a factual explanation for some natural
phenomenon. It is supported by measurable data collected from numerous
experiments used to test the hypothesis.
Examples: For years, it was not really known what was the exact cause of tooth
decay. Various hypotheses were proposed that acid, sugar, tooth hygiene, and other
factors were involved. Finally, after having the correct conditions for
experimentation (on animals that lacked normal resident microbes), it was
determined that a combination of excess dietary sugar, lack of cleaning, and certain
streptococci living in the mouth were the primary factors.
Likewise, the germ theory of disease started out as a hypothesis, but after thorough
verification, it became not only a theory, but is now considered a law because it has
held true over several centuries of investigation.
5. Classification of microbes
Evolution is a process by which organisms gradually change (evolve) over long
periods of time through inheritance of modified characteristics from ancestors. It
asserts that all organisms arise from preexisting forms and that this relatedness
shows itself by similarities in structure, physiology, and genetics. Biologists and
microbiologists use various means to show the pattern of evolution, including trees,
taxonomy, classification, and nomenclature.
,Taxonomy is a hierarchical system, from general to specific, for assembling
organisms into a scheme that emphasizes their origins and relatedness. Classification
is the process of collecting organisms into distinct taxonomic groups according to
defined characteristics. Nomenclature is the naming of these categories in
collaboration with their level of classification. Most classification schemes are based
on evolutionary relatedness, with organisms that are more closely related placed in
the same taxonomic groups.
The correct order of taxa, from broadest and most inclusive to most specific, is:
Domain, Kingdom, Phylum, Class, Order, Family, Genus, and Species. The five
Kingdom system groups the archaea with the bacteria in the prokaryotic category. In
comparison the domain system emphasizes the evolutionary separation of the
Archaea from the Bacteria and their early relatedness with the Eukarya.
The binomial system of nomenclature assigns a genus and species (scientific) name
to each organism; the first letter of the genus is capitalized, the species is lowercase,
and the two names are underlined or italicized. This system standardizes naming
and ensures consistency and universality. Names may also provide an indication of
noteworthy characteristics of the organisms or its discoverer.
6. Sources for new infections
(a) A large number of new infectious diseases arise from animals living in
environments where they have crossed paths with humans. Since 1969, at least 20
new viral diseases have been reported in humans (see Making Connections 25.1).
Most of these have not spread uncontrollably through the population, but a few,
such as HIV and Zika virus infections, developed into pandemics. Some of the new
diseases are caused by well-known microbes that have become drug resistant
(MRSA) and others have mutated to become more infectious for human beings
(some influenza strains).
(b) Most of the time outbreaks of newer diseases receive more negative attention
from the media than is warranted, often leading to unfounded fear of diseases and
germ phobia rather than helping to educate and inform the public. Understanding
the facts about disease outbreaks and learning methods of dealing with them would
be a much more valuable contribution to sensible coverage.
Chapter 2
, 1. Explain why all compounds are molecules but not visa versa.
A molecule is any combination of two or more bonded atoms, regardless of the types
of atoms present. Compounds are molecules that contain at least two different
atoms. For example, O2 and N2 are molecules but not compounds, whereas CO 2 and
NaCl are both molecules and compounds.
2. What causes bonding?
Atoms form chemical bonds because they have a structure that allows them to lose,
gain, or share the electrons in their outer orbitals. Covalent bonds form when atoms
share electrons. Elements that tend to make covalent bonds have valences that are
more suitable for sharing electrons rather than donating or receiving.
Ionic bonds form when an atom donates electrons to another atom, which leaves the
participating atoms now oppositely charged. Atoms with unfilled outer electrons
shells can easily lose or gain electrons to create stability and usually form ionic
bonds.
Hydrogen bonds from between atoms that have polar covalent bonds that are
shared unequally. This creates partial charges on atoms within molecules and
creates attraction between oppositely charged atoms on the same or adjacent
molecules.
3. Why are some covalent molecules polar and others nonpolar?
Polarity of covalent molecules arises when the electron pairs of atoms in the
molecule are being shared unequally. This is usually because the atoms differ greatly
in the sizes of their atomic nuclei and number of protons. The atom exerting greater
electronegativity (pull on the electrons) keeps the electrons in its sphere. Examples
of molecules that show polarity are H20 and phospholipids. Since water is a polar
molecule, it allows intramolecular hydrogen bonding, which makes water cohesive.
4. What causes diatomic molecules?
A few elements exist in their natural elemental state as two identical atoms bonded
by a covalent bond. Examples include oxygen (O 2), hydrogen (H2), and chlorine (Cl2).
This state arises from the electron numbers in their outer orbitals. Diatomic
elements are most stable when they share these electrons with a partner having the
same number of electrons. Chlorine, for example, has a single unpaired electron that
