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Week 2, Session 1
Chapters 26-27
Important text sections: 26.1, 26.3, 26.6,
27.1, 27.2,
Supplemental Instruction
Iowa State University
Leader: Kelsey
Course: Bio 211
Instructor: Dr. Holscher
Date: 8-31-09
Phylogeny
1. Who first developed the binomial nomenclature system? Carolus Linneaus
a. What are the two components of the binomial nomenclature format?
genus and species
b. Give an example of this format:
homo sapiens
Cladistics
1. What is the primary criterion in the methodology of cladistics?
Common ancestry is the primary criterion used in cladistics.
2. A true clade is:
a. monopyletic
b. paraphyletic
c. polyphyletic
3. Draw an example of a clade:
Three Domain System
1. What are the domains are found in the three-domain system?
 Eukarya
 Bacteria
 Archaea
Supplemental Instruction
1060 Hixson-Lied Student Success Center  294-6624  www.si.iastate.edu
Characteristics of Prokaryotes
1. List four characteristics of prokaryotes:
 able to live in extreme environments
 first organism on earth
 unicellular
 have a diameter of around 0.5-5 micrometers
2. Name and draw the three common shapes of prokaryotes:
Cocci (spherical)
Bacilli (rod-shaped)
Spriochetes (spiral)
3. A gram-positive__ bacteria has a thick cell wall made of peptidoglycan that causes it to appear
purple_ during gram staining.
4. A gram-negative bacteria has a thin layer of peptidoglycan sandwiched between two
membranes that causes it to appear _pink/red_ during gram staining.
5. Match the following prokaryotic cell structures with their function:
1. capsule
__a__
a. a sticky layer that allows prokaryotes to adhere to
other things
2. fimbriae __c__
b. a structure that enables motility by propulsion
c. hair-like appendages that aid the cell in sticking to
3. sex pili
__d__
other things
d.
an appendage used to pull two cells together for
4. flagellum __b__
DNA transfer
e.
resistant cells that form when nutrients are lacking
5. endospores __e__
6. List and describe the three ways in which prokaryotes perform genetic recombination:
Transformation
A prokaryotic cell takes up
foreign DNA from its
surroundings.
Transduction
Conjugation
Bacteriophages move bacterial Two bacterial cells
genes from one host to a
temporarily join and transfer
different host.
the material between them.
7. Describe the four modes of nutrition in prokaryotes:
Photoautotrophs
Use light energy to
drive synthesis of
organic compounds.
Chemoautotrophs
Oxidize inorganic
substances to use as a
carbon source.
Photoheterotrophs
Use light energy and
must obtain carbon in
organic form.
Chemoheterotrophs
Must consume
organic molecules for
energy and carbon.
8. Write in the name of the oxygen-use type that matches the given definitions:
Obligate aerobe
Require oxygen for cellular
respiration, cannot grow
without oxygen.
Obligate anaerobe
Are poisoned by oxygen,
cannot grow in the presence of
oxygen.
Facultative anaerobe
Use oxygen if it is present but
can also grow without oxygen.
9. What is the most important role that prokaryotes play in the biosphere?
Decomposers- break down corpses, waste, and dead plants which releases carbon and nitrogen.
10. Describe the four types of ecological interactions that exist between prokaryotes and other
organisms:
 Symbiosis: a relationship in which two species live in close contact
o Mutualism: both species benefit
o Commensalism: one species benefits, the other is neither harmed nor helped
o Parasitism: a parasite eats the tissues or fluids of its host, which harms the
host
Archaea
1. Name the three types of extremophiles, and describe their living conditions/preferences:
Halophiles
Either tolerate or prefer highly
saline environments.
Thermophiles
Thrive in extremely hot
environments.
Methanogens
Obtain energy by using carbon
dioxide to oxidize hydrogen
gas, releasing methane as a
waste product.
Bacteria
1. True or false: All bacteria are pathogenic (harmful). _False
a. If this is false, give an example of a non-pathogenic (beneficial) type of bacteria:
Many are found in human intestines. We have a mutualistic relationship with
these bacteria and depend on them to help digest some foods we eat.
2. __Exotoxins___ are poisonous illness-causing proteins secreted by bacteria and other
organisms. An example of this type of toxin is _cholera_.
3. _Endotoxins______ are components of the outer membrane of some types of bacteria that are
released when the cell walls break down. An example of this type of toxin is _salmonella_.
4. List four ways in which bacteria and/or archaea are being used in research, technology, and
industry today:
 Food production- cheese and yogurt
 Bioremediation- use of organisms to remove pollutants from soil, air, and water
 Production of natural plastics
 Modification of vitamins, antibiotics, and hormones