Chapter 10: Classification of Microorganisms
Below you will find answers to the "Review" study questions found at the end of this
chapter in Microbiology: An Introduction, 7th edition.
1. Taxonomy is the science of classifying organisms to establish the relatedness
between groups of organisms.
2. The three distinct chemical types of cells (see Table 10.1).
3. Living organisms cannot be grouped into two groups. For example, plant and
animal is not acceptable because if fungi are grouped with plants, the definition
of plants can't include cellulose and photosynthesis. If fungi are grouped with
animals, the definition of animals can't include no cell wall and ingestive. The
goal is to look for a "natural" scheme; that is, what criteria can be used to
characterize all organisms.
4. Fungi: Unicellular or multicellular organisms that absorb organic nutrients;
noncellulose cell walls; lack flagella.
Plantae: Multicellular eukaryotes with tissue formation; cellulose cell walls;
generally photosynthetic.
Animalia: Multicellular eukaryotes with tissue formation; develop from an embryo
(gastrula); lacking cell walls; ingest organic nutrients through a mouth of some
kind.
5.
a. Both are prokaryotic. They differ in composition of their cell walls, plasma
membranes, and rRNAs.
b. Both are bound by ester-linked plasma membranes. Eukarya have
membrane-bound organelles.
c. Both use methionine as the start signal. Eukarya have membrane-bound
organelles and ester-linked membranes.
6. Binomial nomenclature is the system of assigning a genus and specific epithet
to each organism.
7. Common names are not specific and can be misleading. According to the rules
of scientific nomenclature, each organism has only one binomial.
8. The genus name must be written out so the reader knows what organism is
being discussed, since the abbreviation for both of these species is E. coli.
9. Domain, kingdom, phylum, class, order, family, genus, species.
10. A eukaryotic species is a group of closely related organisms having limited
geographical distribution that interbreeds but does not breed with other species.
Species can be distinguished morphologically. Because of the distinct
differences between eukaryotic organisms and bacteria, a bacterial species is
defined as a population of cells with similar characteristics. A viral species is a
population of viruses with similar characteristics that occupies a particular
ecological niche.
11. (See Table 10.5)
Used primarily for identification:
morphological characteristics
differential staining
biochemical tests
serology
phage typing
fatty acid profiles
Used primarily for taxonomic classification:
flow cytometry
DNA base composition
DNA fingerprinting
rRNA sequencing
PCR
nucleic acid hybridization
Data obtained from laboratory tests employing any (or all) of these twelve
techniques can be assimilated using numerical taxonomy to provide information
on classification.
12. Most microorganisms do not contain structures that are readily fossilized,
making it difficult to obtain information on the evolution of microorganisms.
Recent developments in molecular biology have provided techniques for
determining evolutionary relationships amongst bacteria.
13. A and D appear to be most closely related because they have similar G-C moles
%. No two are the same species.
Below you will find answers to the "Multiple-Choice" study questions found at the end
of this chapter in Microbiology: An Introduction, 7th edition.
1. b
2. e
3. d
4. b
5. e
6. a
7. a
8. e
9. a
10. b
Note: The answers to the Critical Thinking and Clinical Applications questions are
available to instructors only, and are found in the Instructor's Manual.