27.3 Diverse nutritional and metabolic adaptations have evolved in prokaryotes

Question 1

1. autotroph
2. heterotroph
3. phototroph
4. chemotroph
   40) an organism that obtains its energy from chemicals
   A) 1 only
   B) 2 only
   C) 3 only
   D) 4 only
   E) 1 and 4

Answer 1

D) 4 only

Question 2

1. autotroph
2. heterotroph
3. phototroph
4. chemotroph

41) a prokaryote that obtains both energy and carbon as it decomposes dead organisms
A) 1 only
B) 4 only
C) 1 and 3
D) 2 and 4
E) 1, 3, and 4

Answer 2

D) 2 and 4

Question 3

1. autotroph
2. heterotroph
3. phototroph
4. chemotroph

42) an organism that obtains both carbon and energy by ingesting prey
A) 1 only
B) 4 only
C) 1 and 3
D) 2 and 4
E) 1, 3, and 4

Answer 3

D) 2 and 4

Question 4

1. autotroph
2. heterotroph
3. phototroph
4. chemotroph

43) an organism that relies on photons to excite electrons within its membranes
A) 1 only
B) 3 only
C) 1 and 3
D) 2 and 4
E) 1, 3, and 4

Answer 4

B) 3 only

Question 5

44) Which of the following are responsible for many human diseases?
A) photoautotrophs
B) photoheterotrophs
C) chemoautotrophs
D) chemoheterotrophs that perform decomposition
E) parasitic chemoheterotrophs

Answer 5

E) parasitic chemoheterotrophs

Question 6

45) Cyanobacteria are
A) photoautotrophs.
B) photoheterotrophs.
C) chemoautotrophs.
D) chemoheterotrophs that perform decomposition.
E) parasitic chemoheterotrophs.

Answer 6

A) photoautotrophs.

Question 7

46) Which of the following use light energy to synthesize organic compounds from CO2?
A) photoautotrophs
B) photoheterotrophs
C) chemoautotrophs
D) chemoheterotrophs that perform decomposition
E) parasitic chemoheterotrophs

Answer 7

A) photoautotrophs

Question 8

47) Which of the following obtain energy by oxidizing inorganic substances; energy that is
used, in part, to fix CO2?
A) photoautotrophs
B) photoheterotrophs
C) chemoautotrophs
D) chemoheterotrophs that perform decomposition
E) parasitic chemoheterotrophs

Answer 8

C) chemoautotrophs

Question 9

48) Which of the following use light energy to generate ATP, but do not release oxygen?
A) photoautotrophs
B) photoheterotrophs
C) chemoautotrophs
D) chemoheterotrophs that perform decomposition
E) parasitic chemoheterotrophs

Answer 9

B) photoheterotrophs

Question 10

49) Which of the following are responsible for high levels of O2 in Earthʹs atmosphere?
A) photoautotrophs
B) photoheterotrophs
C) chemoautotrophs
D) chemoheterotrophs that perform decomposition
E) parasitic chemoheterotrophs

Answer 10

A) photoautotrophs

Question 11

50) Modes of obtaining nutrients, used by at least some bacteria, include all of the following
except
A) chemoautotrophy.
B) photoautotrophy.
C) heteroautotrophy.
D) chemoheterotrophy.
E) photoheterotrophy.

Answer 11

C) heteroautotrophy.

Question 12

51) Only certain prokaryotes can perform nitrogen fixation, but nitrogen-fixing prokaryotes
are not known to live inside animals. Thus, how do animals gain access to fixed nitrogen?
A) They may breathe it in from air that has experienced lightning discharges.
B) They may ingest nitrogen fixers.
C) They may ingest plants that harbor nitrogen fixers, or plants that absorbed fixed
nitrogen from the soil.
D) They may ingest other animals that had done either (B) or (C) above.
E) Answers (B), (C), and (D) above are all possible.

Answer 12

E) Answers (B), (C), and (D) above are all possible.

Question 13

52) Given that the enzymes that catalyze nitrogen fixation are inhibited by oxygen, what are
two ʺstrategiesʺ that nitrogen-fixing prokaryotes might use to protect these enzymes from
oxygen?
1. couple them with photosystem II (the photosystem that splits water molecules)
2. package them in membranes that are impermeable to all gases
3. be obligate anaerobes
4. be strict aerobes
5. package these enzymes in specialized cells or compartments that inhibit oxygen entry
A) 1 and 4
B) 2 and 4
C) 2 and 5
D) 3 and 4
E) 3 and 5

Answer 13

E) 3 and 5

Question 14

53) Nitrogenase, the enzyme that catalyzes nitrogen fixation, is inhibited whenever free O2
reaches a critical concentration. Consequently, nitrogen fixation cannot occur in cells
wherein photosynthesis produces free O2. Consider the colonial aquatic cyanobacterium,
Anabaena, whose heterocytes are described as having ʺ…a thickened cell wall that restricts
entry of O2 produced by neighboring cells. Intracellular connections allow heterocytes to
transport fixed nitrogen to neighboring cells in exchange for carbohydrates.ʺ Which two
questions below arise from a careful reading of this quotation, and are most important for
understanding how N2 enters heterocytes, and how O2 is kept out of heterocytes?
1. If carbohydrates can enter the heterocytes from neighboring cells via the ʺintracellular
connections,ʺ how is it that O2 doesnʹt also enter via this route?
2. If the cell walls of Anabaenaʹs photosynthetic cells are permeable to O2 and CO2, are they
also permeable to N2?
3. If the nuclei of the photosynthetic cells contain the genes that code for nitrogen fixation,
how can these cells fail to perform nitrogen fixation?
4. If the nuclei of the heterocytes contain the genes that code for photosynthesis, how can
these cells fail to perform photosynthesis?
5. If the cell walls of Anabaenaʹs heterocytes are permeable to N2, how is it that N2 doesnʹt
diffuse out of the heterocytes before it can be fixed?
6. If the thick cell walls of the heterocytes exclude entry of oxygen gas, how is it that they
donʹt also exclude the entry of nitrogen gas?
A) 3 and 4
B) 2 and 5
C) 1 and 3
D) 4 and 6
E) 1 and 6

Answer 14

E) 1 and 6