27.5 Prokaryotes play crucial roles in the biosphere

Question 1

64) The termite gut protist, Mixotricha paradoxa, has at least two kinds of bacteria attached to its
outer surface. One kind is a spirochete that propels its host through the termite gut. A
second type of bacteria synthesizes ATP, some of which is used by the spirochetes. The
locomotion provided by the spirochetes introduces the ATP-producing bacteria to new
food sources. Which term(s) is (are) applicable to the relationship between the two kinds of
bacteria?
1. mutualism
2. parasitism
3. symbiosis
4. metabolic cooperation
A) 1 only
B) 1 and 2
C) 2 and 3
D) 1, 3, and 4
E) all four terms

Answer 1

D) 1, 3, and 4

Question 2

65) What is the primary ecological role of prokaryotes?
A) parasitizing eukaryotes, thus causing diseases
B) breaking down organic matter
C) metabolizing materials in extreme environments
D) adding methane to the atmosphere
E) serving as primary producers in terrestrial environments

Answer 2

B) breaking down organic matter

Question 3

66) If all prokaryotes on Earth suddenly vanished, which of the following would be the most
likely and most direct result?
A) The number of organisms on Earth would decrease by 10—20%.
B) Human populations would thrive in the absence of disease.
C) Bacteriophage numbers would dramatically increase.
D) The recycling of nutrients would be greatly reduced, at least initially.
E) There would be no more pathogens on Earth.

Answer 3

D) The recycling of nutrients would be greatly reduced, at least initially.

Question 4

67) In a hypothetical situation, a bacterium lives on the surface of a leaf, where it obtains
nutrition from the leafʹs nonliving, waxy covering, while inhibiting the growth of other
microbes that are plant pathogens. If this bacterium gains access to the inside of a leaf, it
causes a fatal disease in the plant. Once the plant dies, the bacterium and its offspring
decompose the plant. What is the correct sequence of ecological roles played by the
bacterium in the situation described here? Use only those that apply.
1. nutrient recycler
2. mutualist
3. commensal
4. parasite
5. primary producer
A) 1, 3, 4
B) 2, 3, 4
C) 2, 4, 1
D) 1, 2, 5
E) 1, 2, 3

Answer 4

C) 2, 4, 1

Question 5

68) How can prokaryotes be considered to be more successful on Earth than humans?
A) Prokaryotes are much more numerous and have more biomass.
B) Prokaryotes occupy more diverse habitats.
C) Prokaryotes are more diverse in metabolism.
D) Only B and C are correct.
E) A, B, and C are correct.

Answer 5

E) A, B, and C are correct.