Deck 26: Bacteria and Archaea

Question 1

As diffusion plays a large role in determining the size of bacterial cells, bacteria are often shaped like which of the following?

A)spheres
B)spirals
C)filaments
D)rods
E)All of these choices are correct.

Answer 1

E

Question 2

Which of these trees reflects the hypothesis that Archaea are more closely related to Eukarya than they are to Bacteria?

Answer 2

A

Question 3

A biologist draws a tree of life having only three branches. Which of the following groups did the biologist MOST likely choose for her diagram?

A)fungi, Eukarya, and vertebrates
B)Archaea, Bacteria, and Eukarya
C)vertebrates, Bacteria, and Archaea
D)Bacteria, fungi, and Archaea
E)Eukarya, Bacteria, and fungi

Answer 3

B

Question 4

Plasmid DNA generally contains genetic information critical for the survival of a bacterial cell.

Question 5

The last common ancestor of fungi, mammals, and archaeons likely had which of the following characteristics?

A)both a plasma membrane and a circular chromosome
B)both a circular chromosome and membrane-bound organelles
C)both free-floating genetic material (DNA)and a distinct nucleus
D)both membrane-bound organelles and a circular chromosome
E)both a distinct nucleus and a plasma membrane

Question 6

Which of the following statements is TRUE regarding archaeons?

A)Like bacteria, they are killed by peptidoglycan-targeting antibiotics.
B)They have cell walls composed of chitin.
C)They do not include organisms that can undergo methanogenesis.
D)Unlike bacteria, their cell size and cell shape is not determined by diffusion.
E)Their transcriptional machinery is similar to the machinery used by eukaryotes.

Question 7

Which of the following characteristics are unique to eukaryotes (i.e., do NOT occur in either archaea or bacteria)?

A)the presence of introns in most genes (noncoding stretches of DNA)
B)the presence of exons in most genes (coding stretches of DNA)
C)the presence of chlorophyll
D)the presence of nuclei

Question 8

_____ is a type of horizontal gene transfer during which genetic information is transferred from one bacterium to another by a virus.

A)Transduction
B)Transformation
C)Transferation
D)Conjugation
E)Conduction

Question 9

Bacterial genetic diversity can arise from:

A)sexual reproduction.
B)transduction and conjugation.
C)meiotic recombination.
D)meiotic recombination and conjugation.
E)horizontal gene transfer and sexual reproduction.

Question 10

A researcher discovers a new unicellular organism that contains a single circular chromosome and no membrane-bound organelles. Upon closer observation, the researcher notices that this organism can also fix nitrogen and produce methane. How should this organism be classified?

A)as a bacterium
B)as an archaeon
C)as a eukaryote

Question 11

Conjugation is a type of horizontal gene transfer that relies on a structure known as a pilus to bring two cells into close enough contact to transfer genetic material.

Question 12

Horizontal gene transfer can happen through:

A)meiosis.
B)transformation.
C)mitosis.
D)conjugation.

Question 13

A researcher synthesizes a new drug that specifically targets and degrades peptidoglycan. What type of infections could this drug treat?

A)infections caused by archaeonsNo,
B)infections caused by bacteria
C)infections caused by viruses
D)infections caused by eukaryotes

Question 14

Recall that Archaea and Bacteria used to be grouped in the same category. How were archaeons FIRST distinguished from other prokaryotes?

A)through differences in cell size and shape
B)through the fact that archaeons have linear and not circular chromosomes
C)through differences in ribosomal RNA sequences
D)through the lack of horizontal gene transfer in archaeons
E)through the observation that archaea cell size is independent of diffusion

Question 15

Many antibiotics that target bacteria are effective against Archaea.

Question 16

Given the features found individually in Archaea, Bacteria, and Eukarya, what features were probably present in the last common ancestor of all living things?

A)prokaryotic cell organization
B)photosynthesis
C)a membrane-bounded nucleus
D)DNA in a single circular chromosome

Question 17

A researcher discovers a new single-celled bacterium very similar to Thiomargarita namibiensis. At first she is confused because this organism is quite large compared with other bacteria. She also knows that because of diffusion, most bacterial cells don't exceed 1 $\mu$ m in size. What might the researcher notice about the internal structure of her new bacterium?

A)It contains several membrane-bound organelles, facilitating the diffusion of molecules.
B)It contains several large histones, facilitating the diffusion of molecules.
C)It is completely filled by cytoplasm, limiting the distance molecules need to diffuse.
D)It contains a large vacuole, limiting the distance molecules need to diffuse.

Question 18

Viruses transmit bacterial genetic material from one bacterium to another in a type of horizontal gene transfer referred to as _____.

Question 19

Why would streptomycete bacteria be of particular interest to a pharmaceutical company?

A)Streptomycete bacteria produce antibiotic or antifungal compounds.
B)All streptomycete bacteria are antibiotic-resistant.
C)Streptomycete bacteria have cell walls made of lignin and not peptidoglycan.
D)Streptomycete bacteria change color when exposed to antibiotics.

Question 20

_____ effectively limits how large a bacterium can grow. The bigger the bacterial cell, the less likely it is that nutrients can reach the cell's interior.

A)Conjugation
B)Differentiation
C)Transduction
D)Diffusion

Question 21

If scientists could quantify all the bacterial and human cells on Earth, they would find that there are far more human cells.

Question 22

What is one advantage of fermentation over cellular respiration in certain environments?

A)Fermentation does not require O₂.
B)Fermentation breaks down organic molecules.
C)Fermentation yields more energy.
D)None of the answer options is correct.

Question 23

Which is NOT a difference between anoxygenic photosynthetic organisms and oxygenic photosynthetic organisms?

A)source of electrons
B)type of chlorophyll
C)number of photosystems
D)wavelengths at which light is absorbed.
E)need for a source of carbon

Question 24

An organism that acquires energy from the sun and uses C₆H₁₂O₆ as a carbon source would be classified as a:

A)photoautotroph.
B)chemoautotroph.
C)photoheterotroph.
D)chemoheterotroph.

Question 25

A marine biologist descends in a submarine through the waters of the Black Sea. The top hundred meters or so are well oxygenated, but deeper waters are rich in hydrogen sulfide. What biological metabolisms can explain the distribution of H₂S in the Black Sea?

A)Chemoautotrophic bacteria oxidize H₂S in deep Black Sea waters.
B)Chemoautotrophic bacteria oxidize H₂S at the boundary between oxygen-rich surface waters and oxygen-poor deep waters.
C)Photosynthetic bacteria deplete H₂S in surface waters of the Black Sea.
D)Anaerobic respiration by sulfate-reducing bacteria continually generates H₂S in deep Black Sea waters.

Question 26

During oxygenic photosynthesis, water is _____ and loses electrons. (i.e., it serves as an electron donor).

A)converted
B)reduced
C)oxidized
D)transformed

Question 27

A researcher wants to determine if a unicellular organism he discovered is an autotroph or a heterotroph. He radioactively labels the carbon in CO₂ and C₆H₁₂O₆, and exposes one culture of his organism to the labeled CO₂ and another culture to the labeled C₆H₁₂O₆. What would happen if his organism is an autotroph?

A)Labeled carbon would be seen in the carbohydrates of organisms exposed to CO₂.
B)Labeled carbon would be seen in the carbohydrates of organisms exposed to C₆H₁₂O₆.
C)Labeled carbon would not be seen in the carbohydrates of either culture.
D)Labeled carbon would be seen in carbohydrates of both cultures.

Question 28

Fermentation yields an amount of energy equivalent to respiration because both processes achieve full oxidation of carbon compounds to CO₂.

Question 29

A researcher is studying a specific strain of bacteria. In one of her cultures, she notices that the bacteria are antibiotic-resistant. As there are no genes in the chromosome that could confer antibiotic-resistance in these bacteria, the researcher assumes this is the result of a spontaneous mutation. What is another possible explanation?

A)A gene conferring antibiotic resistance is present on ribosomes.
B)A gene conferring antibiotic resistance is present on peptidoglycans.
C)A gene conferring antibiotic resistance is present on plasmids.
D)A gene conferring antibiotic resistance is present on mitochondria.

Question 30

A researcher is comparing the sequences of genes encoding cell wall proteins in archaeons with those coding cell wall proteins in bacteria. How similar do you expect these sequences will be?

A)These sequences will be similar, as both archaeons and bacteria have cell walls composed of peptidoglycan variants.
B)These sequences will be dissimilar, as archaeons have chitin-based cell walls and bacteria primarily have peptidoglycan-based cell walls.
C)These sequences will be dissimilar, as archaeon cell walls are not composed of peptidoglycan.
D)These sequences will be similar, as bacteria and archaeons belong to the same prokaryotic domain.

Question 31

The text discusses the metabolisms that link the N and S cycles to Earth's biological carbon cycle. Can you outline ways in which the carbon cycle might also be linked to the biological cycling of iron?

Question 32

If biologists could quantify all the bacterial and human cells within the human body, they would find that there are far more human cells.

Question 33

Autotrophs produce carbohydrates by reducing CO₂, whereas heterotrophs synthesize carbohydrates by ingesting smaller preformed organic compounds like glucose.

Question 34

A doctor is treating a patient for an apparent bacterial infection. She prescribes antibiotics that target either the peptidoglycan in bacterial cell walls or the bacterial translational machinery. To her surprise, this treatment does not work. Why might this treatment be ineffective?

A)The bacterium may have developed resistance to these treatments.
B)The patient may be infected with bacteria that have cell walls composed of chitin.
C)The patient may be infected with bacteria that have cell walls composed of cellulose.
D)All of these choices are correct.

Question 35

All bacteria are unicellular.

Question 36

Imagine you are talking to your friend who is very excited because he has just transduced his first batch of bacteria in the laboratory. What does this mean?

A)He introduced a gene of interest into his bacteria using viruses.
B)He introduced a gene of interest into his bacteria using other bacterial species that can form pili.
C)He introduced a gene of interest into his bacteria by lysing other bacterial cells and exposing his bacteria to this mixture.
D)He produced a strain of antibiotic-resistant bacteria by exposing his bacterial cultures to antibiotics.
E)Through periodic selection, he was able to isolate a gene of interest in his bacteria.

Question 37

Imagine that a scientist is able to reverse the principles of diffusion, such that molecules preferentially move from regions of low concentrations to regions of high concentrations. How would this affect the morphology of bacteria?

A)This change would not likely affect bacteria morphology, as diffusion plays no role in determining bacteria shapes.
B)Bacteria would have to actively transport molecules across the cell membrane, potentially allowing for bacteria to grow larger.
C)Bacteria would have to prevent the diffusion of molecules out of the cell, potentially allowing for bacteria to grow wider.
D)Bacteria would have to actively transport molecules across the cell membrane, potentially allowing for bacteria to grow larger, and would have to prevent the diffusion of molecules out of the cell, potentially allowing for bacteria to grow wider.

Question 38

Bacteria contain neither organelle-associated membranes nor a cell membrane.

Question 39

Photoheterotrophs rely on sunlight and organic molecules obtained from the environment.

Question 40

An organism that oxidizes H₂S to gain energy and utilizes CO₂ as a carbon source (to generate carbohydrates) would be classified as a:

A)photoautotroph.
B)chemoautotroph.
C)photoheterotroph.
D)chemoheterotroph.

Question 41

Fermentation can be performed only by bacteria and not by archaeons.

Question 42

If you were to analyze the deepest layer of a microbial mat along a coastline (i.e., the layer farthest away from the surface of the water), you would find that H₂S levels sharply increase, as do the numbers of chemoautotrophic microorganisms.

Question 43

During _____ photosynthesis, H₂S, H₂, Fe²⁺, or AsO₃^3- can be oxidized.

Question 44

Which of the following organisms can function as chemoautotrophs?

A)eukaryotes
B)bacteria
C)archaeons

Question 45

Phototrophs use light as the energy source for biosynthesis, whereas chemotrophs oxidize either organic or inorganic compounds to obtain energy for biosynthesis.

Question 46

Based on the energy and carbon sources used by humans, in what way would humans be classified?

A)as chemoautotrophs
B)as chemoheterotrophs
C)as photoheterotrophs
D)as photoautotrophs

Question 47

A researcher discovers a new prokaryote that lives on the seafloor near hydrothermal vents. This organism reduces CO₂ to form C₆H₁₂O₆, and also derives energy from H₂ (by oxidation). This prokaryote is a:

A)photoautotroph.
B)photoheterotroph.
C)chemoheterotroph.
D)chemoautotroph.

Question 48

Chemoautotrophy is unique to prokaryotes because eukaryotes cannot use inorganic compounds as a chemical energy source.

Question 49

As part of aerobic respiration, O₂ is reduced and loses electrons, and glucose (C₆H₁₂O₆) is oxidized and gains electrons.

Question 50

Which of the following statements is TRUE regarding fermentation?

A)It can be used as an alternative to photosynthesis.
B)It requires oxygen.
C)It results in the partial oxidation of C₆H₁₂O₆.
D)It releases more energy from C₆H₁₂O₆ than cellular respiration_.
E)None of the other answer options is true.

Question 51

If O₂ and N₂ are present in equal amounts in an environment, both will have an equal chance of serving as an electron acceptor during respiration (i.e., organisms do not have a preference as to which molecule is reduced).

Question 52

Only the inorganic compounds O₂ or NO₃^- may be used as terminal electron acceptors in respiration.

Question 53

An organism classified as a eukaryote could be which of the following?

A)a photoautotroph or a photoheterotroph
B)a chemoheterotroph or a photoautotroph
C)a photoheterotroph or a chemoheterotroph
D)a chemoautotroph or a chemoheterotroph

Question 54

If all eukaryotes suddenly died off, the Earth's carbon cycle would immediately collapse and cease to exist.

Question 55

Oxygen is used during a reaction if the process is:

A)oxygenic.
B)anoxygenic.
C)aerobic.
D)anaerobic.

Question 56

_____ is contained in anoxygenic photosynthetic bacteria and plays a similar role as chlorophyll in cyanobacteria.

Question 57

Which of the following statements is TRUE regarding microbial mats?

A)They contain archaeons.
B)They contain oxygenic photosynthetic bacteria.
C)They contain anoxygenic photosynthetic bacteria.
D)Sunlight does not reach microbial mat levels inhabited chiefly by chemoautotrophs.
E)All of these choices are correct.

Question 58

Respiration is strictly an aerobic process.

Question 59

During _____ photosynthesis, H₂O is oxidized.

Question 60

Organisms belonging to the Bacteria branch of the tree of life can demonstrate which of the following processes?

A)anoxygenic photosynthesis
B)oxygenic photosynthesis
C)anaerobic respiration
D)aerobic respiration
E)fermentation

Question 61

In what part of the ocean is denitrification likely to be MOST important?

A)shallow waters rich in oxygen
B)subsurface water masses that contain little or no oxygen
C)surface waters of the open ocean
D)deep within marine sediments

Question 62

Nitrification, or the oxidation of ammonia to nitrate (NO₃^-), is a strictly anaerobic process.

Question 63

Which of the following elements are cycled, due in part to the actions of archaeons and bacteria?

A)carbon
B)sulfur
C)nitrogen
D)All of these elements are cycled.

Question 64

During _____, N₂ within the atmosphere is converted to NH₃. Primary producers can then use the nitrogen from NH₃ to build organic compounds.

Question 65

Sulfur is an integral part of which of the following molecules?

A)vitamins
B)enzymes
C)amino acids
D)cofactors
E)Sulfur can be an integral component of any of these molecules.

Question 66

Anammox is represented by which of the following equations?

A)NH₄⁺ + 2H₂O $\rightarrow$ NO₂ + 4H₂
B)N₂ + 2H₂O $\rightarrow$ NH₄⁺ + NO₂^-
C)NH₄⁺ + NO₂^- $\rightarrow$ N₂ + 2H₂O
D)NO₂^- + 4H₂ $\rightarrow$ NH₄^- + 2H₂O
E)2H₂O + 2NO₃^- $\rightarrow$ 2NH₂^- + 4O₂

Question 67

Eukaryotes, archaeons, and bacteria can all successfully oxidize H₂S or NH₄ to form SO₄ or N₂, respectively.

Question 68

The microbial nitrogen and sulfur cycles have many features in common. In what ways are they different?

A)The nitrogen cycle includes chemoautotrophic microorganisms, but the sulfur cycle does not.
B)The sulfur cycle includes photoautotrophic bacteria, but the nitrogen cycle does not.
C)The nitrogen cycle includes metabolic processes that make abundant sources of inorganic nitrogen available to primary producers.
D)The sulfur cycle requires oxygen for completion.

Question 69

Consider the chemical reactions of the sulfur cycle shown in Figure 26.10. Reduction of CO₂ to generate carbohydrates can occur when coupled to the oxidation of reduced sulfur compounds (e.g., H₂S). This latter process is carried out by what type of microorganism(s)?

A)chemoautotrophs
B)heterotrophs

Question 70

Consider the chemical reactions of the sulfur cycle shown in Figure 26.10. Oceans constitute the most significant reservoir of sulfur in the biosphere, and sulfate (SO₄^2-) reduction is the predominant form of anaerobic respiration in marine environments. In such cases, oxidized sulfur compounds like SO₄^2- are the electron acceptors instead of what?

A)water
B)oxygen
C)hydrogen
D)carbon dioxide

Question 71

Through the process of _____, some bacteria derive energy by combining NH₄⁺ and NO₂^- (recall the equation NH₄⁺ + NO₂^- $\rightarrow$ N₂ + 2H₂O).

Question 72

Oxygen is generated during a reaction if the process is:

A)oxygenic.
B)anoxygenic.
C)aerobic.
D)anaerobic.

Question 73

Bacteria and Archaea play an important role in the:

A)carbon cycle.
B)sulfur cycle.
C)nitrogen cycle.
D)None of the answer options is correct.

Question 74

Which of the following statements is TRUE regarding anammox?

A)It can be carried out by both eukaryotes and archaeons.
B)It generates less energy compared to respiration.
C)It is performed in oxygen-rich environments.
D)It is identical to nitrogen fixation.
E)All of these choices are correct.

Question 75

Bacteria or archaeons can be which of the following types of organisms?

A)chemoautotrophs
B)chemoheterotrophs
C)photoautotrophs
D)photoheterotrophs
E)All of these choices are correct.

Question 76

A major constituent of Earth's atmosphere is nitrogen gas (N₂), which makes up 79% of the air we breathe. Primary producers such as plants and algae cannot assimilate this form of nitrogen into biomolecules. Instead they rely on Bacteria and Archaea to convert N₂ to ammonia (NH₃). This important biological reaction is called:

A)denitrification.
B)nitrification.
C)nitrogen fixation.
D)anammox.

Question 77

N₂ is an end product of _____; NH₃ is an end product of _____.

A)anammox; nitrogen fixation
B)nitrogen fixation; anammox
C)denitrification; anammox and nitrogen fixation
D)anammox and denitrification; nitrogen fixation

Question 78

Which of the following are "usable" forms of nitrogen (N) and sulfur (S) that plants and animals can assimilate to build proteins?

A)both N₂ and NO₃
B)both S₂ and S₃
C)both SO₄ and NO₃
D)both NH₃ and S₂
E)both N₂ and S₂

Question 79

Consider the chemical reactions of the sulfur cycle shown in Figure 26.10. Reduction of CO₂ to generate carbohydrates can occur when coupled to the oxidation of reduced sulfur compounds (e.g., H₂S). This latter process is carried out by what type of microorganism(s)?

A)cyanobacteria
B)purple bacteria

Question 80

Archaea and Bacteria are involved in which of the following cycles?

A)the nitrogen cycle
B)the carbon cycle
C)the sulfur cycle