Quiz
Emily Pollock
Multiple Choice – Pick the Best Answer
1. Which of the following nutritional categories of bacteria can exist independently of
other organisms?*
a) Photoautotrophs
b) Photoheterotrophs
c) Photochemotrophs
d) Chemoheterotrophs
2. What is an important structural difference between Archaea and Bacteria?
a) Bacteria do not have a nucleus
b) Archaea have no peptidoglycan in their cell walls
c) Bacteria have cell walls
d) Bacteria have fimbriaea, Archaea have pilli.
3. Which of these is not a domain?
a) Bacteria
b) Archaea
c) Protista
d) Eukarya
4. According to the theory of endosymbiosis:
a) Energy-producing bacteria were engulfed by larger cells, forming plastids
b) Energy-producing bacteria were engulfed by larger cells, forming a mutualist
relationship
c) Energy-producing bacteria were engulfed by larger cells, forming lysozymes
d) Energy-producing bacteria were engulfed by larger cells, forming a parasitic
relationship.
5. A bacterial cell __________________ when resources are scarce.
a) Turns into a heterocyte to save resources
b) Becomes Gram-positive to survive
c) Turns into an endospore to survive
d) Loses motility to save resources
6. Generally, what is the outermost layer of many prokaryotes?
a) Capsid
b) Capsule
c) Cell wall
d) Plasma membrane
7. Why are prokaryotes successful in a broad range of environments?
a) Plasmids allow for adaptation to surroundings
b) Their non-compartmentalized nucleoids allow for a greater rate of
recombination
c) Prokaryotes are very prolific
d) A and C
e) A, B and C
8. B. thetaiotamicron, has a _______________ relationship with humans.
a) Parasitic
b) Commensalistic
c) Endosymbiotic
d) Symbiont
e) Mutualistic
9. On a global basis, Protists are particularly important components of which of the
following habitats? *
a) Marine
b) Freshwater
c) Within the bodies of other organisms
d) Damp soil
10. The big difference between Archaea and other living things is:
a) They don’t use traditional base-pairings.
b) They contain peptidoglycan.
c) They can be baccilus (rod) shape.
d) Their cell membranes don’t contain fatty acid bilayers.
11. Molecular systemetics has helped us determine that:
a) Prokaryotic characteristics are more alike than was previously known
b) Prokaryotes diverged into Bacteria and Archaea early in their lineage.
c) Organisms can be most reliably genetically differentiated by their response to
Gram staining.
d) Most extremophiles are classified under the Archaean clade Korarchaeota.
12. Which of these statements is most true?
a) Obligate aerobes function entirely by fermentation
b) Peptidoglycan, which forms the outer cell wall of bacteria, is a network of
modified lipids cross-linked by short polypeptides.
c) Protista is no longer labeled a kingdom because it has been labeled
prophylactic
d) Cyanobacteria can perform nitrogen fixation.
Short Answer Questions
13. Compare and contrast Gram-positive and Gram negative cells.
14. List and briefly explain the five main types of bacteria mentioned, with examples.
Extending Your Knowledge
15. Summarize the lessons learned through molecular systematics and, given your prior
knowledge of DNA techniques, hypothesize how these conclusions could have been
determined.
* See Works Cited, “Protista”.
Answers
1. a)
2. b)
3. c)
4. a)
5. c)
6. b)
7. d)
8. e)
9. a)
10. d)
11. b)
12. d)
12. Gram-positive and Gram negative cells are different types of bacterial cells,
determined by a staining technique called a Gram stain. Gram-positive cells have a higher
concentration of peptidoglycan, and are simpler and pose less of a threat to humans.
Gram-negative bacteria contain less peptidoglycan because of their more complex outer
membrane, and the higher concentration of lipopolysaccharides. These are more likely to
be dangerous to humans when pathogenic, because the lipopolysaccharides can be toxic
and also because both the body’s natural immune system and antibiotics more easily
target peptidoglycan (easy to target because it is in prokaryotes and not eukaryotes, so we
can use antibiotics that destroy it without killing us as well).
13. Proteobacteria: large, diverse group of Gram-negative bacteria that cover all forms of
nutrition. They are divided up into five subgroups, distinguished by rRNA analysis and
subsequent molecular systemetics:
Alpha: generally associated with eukaryote hosts, includes bacteria that live in
roots of legumes
Beta: Includes soil bacteria that oxidize ammonia into nitrate
Gamma: Includes Salmonella, E. coli, and Cholera
Delta: Includes bacteria that secrete slime and form colonies
Epsilon: Generally pathogenic, includes bacteria that cause blood poisoning.
Chlamydias: Parasites lacking in peptidoglycan walls that cannot function without animal
hosts, includes bacteria that causes nongonococcal urethritis (common STI).
Spirochetes: Helical, heterotrophic cells that move around by using internal filaments.
Includes bacteria that cause syphilis.
Gram-positive bacteria: Diverse group of bacteria only similar in their high density of
peptidoglycan in its cell walls. Includes bacteria that cause anthrax and botulism.
Cyanobacteria: Only prokaryotes with plantlike photosynthesis that generates oxygen.
Includes cyanobacterium Anabena, which lives in colonies that cooperate metabolically
with the aid of heterocytes.
14. Through molecular systematics, scientists have learned that some species previously
classified as prokaryotes actually belong in their own class – Archaea – and that
taxonomic groups that we used to think were monophyletic aren’t. Also, we have
discovered that diversity among groups of prokaryotes is immense – much greater than
was previously thought. One possible way that this could have been determined is
through the previously-mentioned (see Chapter 20) technique of nucleic acid
hybridization, which means checking the frequency of base pairing between genes and
complementary sequences on other genes, which lets scientists see how much of an
organism’s DNA co-responds to another organisms set of DNA, determining relatedness.
(Other techniques discussed in Chapter 20 are acceptable answers, is explained fully).