CHAPTER 18 Test Your Knowledge
Driving Question 1
What are the prokaryotic domains of life?
By answering the questions below and studying Infographics 18.3, 18.4, and 18.5, you should be able to generate an answer for the broader Driving Question above.
KNOW IT
Organisms are placed into one or another of the three domains of life on the basis of
a. cell type.
b. physical appearance.
c. evolutionary history as assessed by genetic relatedness.
d. ability to cause disease.
e. degree of sophistication, that is, how evolutionarily advanced they are.
Describe the major difference(s) between prokaryotic and eukaryotic organisms.
The absence of membrane-bound organelles in a cell tells you that the cell must be
a. from a member of the domain Bacteria.
b. from a member of the domain Archaea.
c. from a member of the domain Eukarya.
d. either a or b
e. either b or c
USE IT
Why were bacteria and archaea originally grouped together?
When first discovered, archaea were called “archaeabacteria.” Why do you suppose this was? What are the strengths and weaknesses of this earlier term?
Driving Question 2
What are the features of bacteria and of archaea?
By answering the questions below and studying Infographics 18.4, 18.6, and 18.7, you should be able to generate an answer for the broader Driving Question above.
KNOW IT
The term prokaryotic refers to
a. a type of cell structure.
b. a domain of life.
c. a group with a shared evolutionary history.
d. a type of bacterium.
e. a type of archaea.
If you were looking for a bacterium, where would expect to find one?
a. on your skin
b. in soil
c. in the ocean
d. associated with plants
e. any of the above
What is the function of flagella?
a. production of methane
b. sticking to a surface
c. motility
d. luminescence
e. metabolism
If you are unable to culture archaea from an environmental sample, is it safe to conclude that there are no archaea present? Why or why not?
USE IT
Can you use cell structure to classify a cell as either bacterial or archaeal? Explain your answer.
Many prokaryotic organisms can carry out both photosynthesis and nitrogen fixation. Why are these processes important to humans?
If Neisseria gonorrhoeae had no pili, would it still be a successful pathogen? Explain your answer.
Driving Question 3
What are the challenges faced by organisms living at Lost City, and how do they face them?
By answering the questions below and studying Infographics 18.1, 18.2, and 18.8, you should be able to generate an answer for the broader Driving Question above.
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KNOW IT
List the features that make Lost City a particularly harsh environment. For each feature, give a brief explanation of why that environment is inhospitable for many organisms.
If you were a prokaryotic organism and wanted to be successful at Lost City, what energy source must you be able to use?
a. sunlight
b. oxygen
c. hydrogen gas
d. electricity
e. None of the above is available at Lost City.
USE IT
What is the significance of methane and other hydrocarbons at Lost City? (Think about both the origin of life and the sustenance of early life.)
If methane were not produced abiotically at Lost City, what would be the implications for early life?
Would you expect to find photosynthetic organisms at Lost City? Explain your answer.
Do you think that the scientists studying Lost City should be concerned about introducing microbial contaminants from their submersibles onto the towers of Lost City? How probable is this, given the conditions at Lost City and on the surface? If such an event could happen, what would be the implications?
INTERPRETING DATA
Some of the chimneys at Lost City are actively venting. These chimneys have hot (80°–100°C) interiors that lack oxygen and have a pH range of 9-11. The exterior surfaces of the active chimneys are cooler (~7°C), contain oxygen and have a pH of ~8.
The inactive chimneys at Lost City are no longer venting hot fluids. Compared to the actively venting chimneys, their interiors are much cooler (7°-20°C), have a pH of 8-10, and lack oxygen. The exteriors of the inactive chimneys are very similar to those of the active chimneys.
From the properties of the organisms given in the table below, complete the table to indicate where in Lost City each of these organisms is most likely to be found.
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MINI CASE
In many ways, the discovery of Lost City is about the discovery of life, as is the voyage of Curiosity to Mars (see Chapter 2).
a. What features do these two environments, Lost City and Mars, share?
b. How do the challenges faced by Curiosity compare to those faced by Jason?
c. From the way microbes survive at Lost City, what properties might you expect Martian organisms to have?
BRING IT HOME
Do you think that, instead of spending time studying microbes from extreme and remote environments, scientists should be studying microbes that are more apparently relevant to humans, such as ones that cause disease? In what ways might understanding the organisms at Lost City be useful to humans?