Gainesville Biology Test 2

Created by ccatmoore 

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Mycoplasmas are bacteria that lack cell walls. On the basis of this structural feature, which statement concerning mycoplasmas should be true?
A) They are gram-negative.
B) They are subject to lysis in hypotonic conditions.
C) They lack a cell membrane as well.
D) They undergo ready fossilization in sedimentary rock.
E) They possess typical prokaryotic flagella.

B

Though plants, fungi, and prokaryotes all have cell walls, we place them in different taxa. Which of these observations comes closest to explaining the basis for placing these organisms in different taxa, well before relevant data from molecular systematics became available?
A) Some closely resemble animals, which lack cell walls.
B) Their cell walls are composed of very different biochemicals.
C) Some have cell walls only for support.
D) Some have cell walls only for protection from herbivores.
E) Some have cell walls only to control osmotic balance.

B

Which is the bacterial structure that acts as a selective barrier, allowing nutrients to enter the cell and wastes to leave the cell?
A) plasma membrane
B) capsule
C) cell wall
D) nucleoid region
E) pili

A

Which statement about bacterial cell walls is false?
A) Bacterial cell walls differ in molecular composition from plant cell walls.
B) Cell walls prevent cells from bursting in hypotonic environments.
C) Cell walls prevent cells from dying in hypertonic conditions.
D) Bacterial cell walls are similar in function to the cell walls of many protists, fungi, and plants.
E) Cell walls provide the cell with a degree of physical protection from the environment.

C

Which of these is the most common compound in the cell walls of gram-positive bacteria?
A) cellulose
B) lipopolysaccharide
C) lignin
D) peptidoglycan
E) protein

D

Penicillin is an antibiotic that inhibits enzymes from catalyzing the synthesis of peptidoglycan, so which prokaryotes should be most vulnerable to inhibition by penicillin?
A) mycoplasmas
B) gram-positive bacteria
C) archaea
D) gram-negative bacteria
E) endospore-bearing bacteria

B

The predatory bacterium, Bdellovibrio bacteriophorus, drills into a prey bacterium and, once inside, digests it. In an attack upon a gram-negative bacterium that has a slimy cell covering which can inhibit phagocytosis, what is the correct sequence of structures penetrated by B. bacteriophorus on its way to the prey's cytoplasm?
1. membrane composed mostly of lipopolysaccharide
2. membrane composed mostly of phospholipids
3. peptidoglycan
4. capsule
A) 2 → 4 → 3 →1
B) 1 → 3 → 4 → 2
C) 1 → 4 → 3 → 2
D) 4 → 1 → 3 → 2
E) 4 → 3 → 1 → 2

D) 4 → 1 → 3 → 2

Jams, jellies, preserves, honey, and other foodstuffs with a high sugar content hardly ever become contaminated by bacteria, even when the food containers are left open at room temperature. This is because bacteria that encounter such an environment
A) undergo death by plasmolysis.
B) are unable to metabolize the glucose or fructose, and thus starve to death.
C) undergo death by lysis.
D) are obligate anaerobes.
E) are unable to swim through these thick and viscous materials.

A) undergo death by plasmolysis.

In a hypothetical situation, the genes for sex pilus construction and for tetracycline resistance are located together on the same plasmid within a particular bacterium. If this bacterium readily performs conjugation involving a copy of this plasmid, then the result should be
A) a transformed bacterium.
B) the rapid spread of tetracycline resistance to other bacteria in that habitat.
C) the subsequent loss of tetracycline resistance from this bacterium.
D) the production of endospores among the bacterium's progeny.
E) the temporary possession by this bacterium of a completely diploid genome.

the rapid spread of tetracycline resistance to other bacteria in that habitat.

In a bacterium that possesses antibiotic resistance and the potential to persist through very adverse conditions, such as freezing, drying, or high temperatures, DNA should be located within, or be part of, which structures?
1. nucleoid region
2. flagellum
3. endospore
4. fimbriae
5. plasmids
A) 1 only
B) 1 and 4
C) 1 and 5
D) 1, 3, and 5
E) 2, 4, and 5

D) 1, 3, and 5

Which two structures play direct roles in permitting bacteria to adhere to each other, or to other surfaces?
1. capsules
2. endospores
3. fimbriae
4. plasmids
5. flagella
A) 1 and 2
B) 1 and 3
C) 2 and 3
D) 3 and 4
E) 3 and 5

B) 1 and 3

The typical prokaryotic flagellum features
A) an internal 9 + 2 pattern of microtubules.
B) an external covering provided by the plasma membrane.
C) a complex "motor" embedded in the cell wall and plasma membrane.
D) a basal body that is similar in structure to the cell's centrioles.

C) a complex "motor" embedded in the cell wall and plasma membrane.

Prokaryotic ribosomes differ from those present in eukaryotic cytosol. Because of this, which of the following is correct?
A) Some selective antibiotics can block protein synthesis of bacteria without effects on protein synthesis in the eukaryotic host.
B) Eukaryotes did not evolve from prokaryotes.
C) Translation can occur at the same time as transcription in eukaryotes but not in prokaryotes.
D) Some antibiotics can block the synthesis of peptidoglycan in the walls of bacteria.
E) Prokaryotes are able to use a much greater variety of molecules as food sources than can eukaryotes.

A) Some selective antibiotics can block protein synthesis of bacteria without effects on protein synthesis in the eukaryotic host.

Which statement about the genomes of prokaryotes is correct?
A) Prokaryotic genomes are diploid throughout most of the cell cycle.
B) Prokaryotic chromosomes are sometimes called plasmids.
C) Prokaryotic cells have multiple chromosomes, "packed" with a relatively large amount of protein.
D) The prokaryotic chromosome is not contained within a nucleus but, rather, is found at the nucleoid region.
E) Prokaryotic genomes are composed of linear DNA (that is, DNA existing in the form of a line with two ends).

D) The prokaryotic chromosome is not contained within a nucleus but, rather, is found at the nucleoid region.

If a bacterium regenerates from an endospore that did not possess any of the plasmids that were contained in its original parent cell, the regenerated bacterium will probably
A) lack antibiotic-resistant genes.
B) lack a cell wall.
C) lack a chromosome.
D) lose base pairs from its chromosome.
E) be unable to survive in its normal environment.

A) lack antibiotic-resistant genes.

Which of the following is composed almost entirely of peptidoglycan?
A) endospore
B) sex pilus
C) flagellum
D) cell wall
E) capsule

D) cell wall

Which of the following requires ATP to function, and permits some species to respond to taxes (plural of taxis)?
A) endospore
B) sex pilus
C) flagellum
D) cell wall
E) capsule

C) flagellum

Not present in all bacteria, this cell covering enables cells that possess it to resist the defenses of host organisms:
A) endospore
B) sex pilus
C) flagellum
D) cell wall
E) capsule

E) capsule

Not present in all bacteria, this structure enables those that possess it to germinate after exposure to harsh conditions, such as boiling:
A) endospore
B) sex pilus
C) flagellum
D) cell wall
E) capsule

A) endospore

Which of the following is a structure that permits conjugation to occur?
A) endospore
B) sex pilus
C) flagellum
D) cell wall
E) capsule

B) sex pilus

Which of the following is an important source of endotoxin in gram-negative species?
A) endospore
B) sex pilus
C) flagellum
D) cell wall
E) capsule

D) cell wall

If this structure connects the cytoplasm of two bacteria, one of these cells may gain new genetic material:
A) endospore
B) sex pilus
C) flagellum
D) cell wall
E) capsule

B) sex pilus

Which of the following contains a copy of the chromosome, along with a small amount of dehydrated cytoplasm, within a tough wall?
A) endospore
B) sex pilus
C) flagellum
D) cell wall
E) capsule

A) endospore

Regarding prokaryotic reproduction, which statement is correct?
A) Prokaryotes form gametes by meiosis.
B) Prokaryotes feature the union of haploid gametes, as do eukaryotes.
C) Prokaryotes exchange some of their genes by conjugation, the union of haploid gametes, and transduction.
D) Mutation is a primary source of variation in prokaryote populations.
E) Prokaryotes skip sexual life cycles because their life cycle is too short.

D) Mutation is a primary source of variation in prokaryote populations.

Which of these statements about prokaryotes is correct?
A) Bacterial cells conjugate to mutually exchange genetic material.
B) Their genetic material is confined within a nuclear envelope.
C) They divide by binary fission, without mitosis or meiosis.
D) The persistence of bacteria throughout evolutionary time is due to their genetic homogeneity (i.e., sameness).
E) Genetic variation in bacteria is not known to occur, nor should it occur, because of their asexual mode of reproduction.

C) They divide by binary fission, without mitosis or meiosis.

Which term best describes what has occurred among the experimental populations of cells over this 8-year period?
A) microevolution
B) speciation
C) adaptive radiation
D) sexual selection
E) stabilizing selection

A) microevolution

If it occurs in the absence of any other type of adaptation listed here, which of these is least reasonable in terms of promoting bacterial survival over evolutionary time in a low-glucose environment?
A) increased efficiency at transporting glucose into the cell from the environment
B) increased ability to survive on simple sugars, other than glucose
C) increased ability to synthesize glucose from amino acid precursors
D) increased reliance on glycolytic enzymes
E) increased sensitivity to, and ability to move toward, whatever glucose is present in its habitat

D) increased reliance on glycolytic enzymes

Which of these can be inferred from Figure 27.1?
A) Most of the genetic change that permitted adaptation to the new, low-glucose environment occurred toward the conclusion of the experiment.
B) Rates of mitosis increased over the course of the experiment.
C) The highest rate of genetic change occurred during the first quarter of the experiment.
D) After 5,000 generations, the bacteria were 100% more fit than the original, ancestral bacteria.

C) The highest rate of genetic change occurred during the first quarter of the experiment.

If the vertical axis of Figure 27.1 refers to "Darwinian fitness," then which of these is the most valid and accurate measure of fitness?
A) number of daughter cells produced per mother cell per generation
B) amount of ATP generated per cell per unit time
C) average swimming speed of cells through the growth medium
D) amount of glucose synthesized per unit time
E) number of generations per unit time

E) number of generations per unit time

) If new genetic variation in the experimental populations arose solely by spontaneous mutations, then the most effective process for subsequently increasing the prevalence of the beneficial mutations in the population over the course of generations is
A) transduction.
B) binary fission.
C) conjugation.
D) transformation.
E) meiosis.

B) binary fission.

E. coli cells typically make most of their ATP by metabolizing glucose. Under the conditions of this experiment, what should be true of E. coli's generation time (especially early in the course of the experiment, but less so later on)?
A) Generation time should be the same as in the typical environment.
B) Generation time should be faster than in the typical environment.
C) Generation time should be slower than in the typical environment.
D) It is theoretically impossible to make any predictions about generation time, under these conditions.

C) Generation time should be slower than in the typical environment.

If the experimental population of E. coli lacks an F factor or F plasmid, and if bacteriophage are excluded from the bacterial cultures, then which of these is a means by which beneficial mutations might be transmitted horizontally to other E. coli cells?
A) via sex pili
B) via transduction
C) via conjugation
D) via transformation
E) both A and C above

D) via transformation

Among the six statements below, which two best account for the results obtained by the researchers (see Figure 27.1)?
1. Low-glucose conditions caused mutations that made individual E. coli cells better suited to these conditions.
2. Daughter cells acquired the ability to tolerate low-glucose conditions as they received the enzymes and membrane components that had been modified by their mother cell.
3. The initial E. coli population may have included some cells whose genes favored their survival in low-glucose conditions-OR-such genetic variants arose by chance early in the experiment.
4. The first few generations of E. coli in low-glucose conditions responded to the challenge by increasing the use of certain enzymes and ion pumps, while decreasing the use of others. This behavior was recorded in their gene sequences, which were later transmitted to daughter cells.
5. From generation to generation, there was an increase in the proportion of the experimental populations adapted to low-glucose conditions, because such bacteria produced relatively more offspring than did ancestral bacteria under low-glucose conditions.
6. During each generation, individual cells evolved to increase their survival in low-glucose conditions.
A) 3 and 5
B) 1 and 5
C) 2 and 4
D) 1 and 6
E) 1 and 3

A) 3 and 5

Which term is least closely associated with the others?
A) Hfr cells making use of a sex pilus
B) rolling circle replication
C) the "toilet paper" model of replication
D) conjugation involving an F factor
E) recombination involving a bacteriophage

E) recombination involving a bacteriophage

What is occurring at Time C that is decreasing the DNA content?
A) crossing-over
B) cytokinesis
C) meiosis
D) degradation of DNA that was not retained in the recipient's chromosome
E) reversal of the direction of conjugation

D) degradation of DNA that was not retained in the recipient's chromosome

How is the recipient cell different at Time D than it was at Time A?
A) It has a greater number of genes.
B) It has a greater mass of DNA.
C) It has a different sequence of base pairs.
D) It contains bacteriophage DNA.
E) It has a greater number of introns.

C) It has a different sequence of base pairs

Which two processes are responsible for the shape of the curve at Time B?
1. transduction
2. entry of single-stranded Hfr DNA
3. rolling circle replication of single-stranded Hfr DNA
4. activation of DNA pumps in plasma membrane
5. "toilet paper" replication of recipient cell's plasmids
A) 1 and 4
B) 2 and 3
C) 3 and 5
D) 1 and 3
E) 4 and 5

B) 2 and 3

During which two times can the recipient accurately be described as "recombinant" due to the sequence of events portrayed in Figure 27.2?
A) during Times C and D
B) during Times A and C
C) during Times B and C
D) during Times A and B
E) during Times B and D

A) during Times C and D

Which question, arising from the results depicted in Figure 27.2, is most interesting from a genetic perspective, and has the greatest potential to increase our knowledge base?
A) If reciprocal crossing-over could occur even if the piece of donated Hfr DNA is identical to the homologous portion of the recipient's chromosome, what prevents this from occurring?
B) Why do geneticists refer to the same structure by at least three different names: sex pilus, mating bridge, and conjugation tube? Why all the jargon?
C) What forces are generally responsible for disrupting the mating bridge?
D) How is it that a recipient cell does not necessarily become an Hfr cell as the result of conjugation with an Hfr cell?
E) What makes a cell an "Hfr cell"?

A) If reciprocal crossing-over could occur even if the piece of donated Hfr DNA is identical to the homologous portion of the recipient's chromosome, what prevents this from occurring?

organism that obtains its energy from chemicals:
1. autotroph
2. heterotroph
3. phototroph
4. chemotroph

A) 1 only
B) 2 only
C) 3 only
D) 4 only
E) 1 and 4

D) 4 only

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

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

D) 2 and 4

A) 1 only
B) 2 only
C) 3 only
D) 4 only
E) 1 and 4

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

D) 2 and 4

A) 1 only
B) 2 only
C) 3 only
D) 4 only
E) 1 and 4

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

B) 3 only

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

E) parasitic chemoheterotrophs

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

A) photoautotrophs.

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

A) photoautotrophs

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

C) chemoautotrophs

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

B) photoheterotrophs

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

A) photoautotrophs

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.

C) heteroautotrophy.

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.

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

Given that the enzymes that catalyze nitrogen fixation are inhibited by oxygen, what are two "strategies" 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

E) 3 and 5

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 "...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." 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 "intracellular connections," how is it that O2 doesn't also enter via this route?
2. If the cell walls of Anabaena's 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 Anabaena's heterocytes are permeable to N2, how is it that N2 doesn't 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 don't 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

E) 1 and 6

The data were collected from the heterocytes of a nitrogen-fixing cyanobacterium inhabiting equatorial ponds. Study the graph below and choose the most likely explanation for the shape of the curve.
A) Enough O2 enters heterocytes during hours of peak photosynthesis to have a somewhat-inhibitory affect on nitrogen fixation.
B) Light-dependent reaction rates must be highest between 1800 hours and 0600 hours.
C) Atmospheric N2 levels increase at night because plants are no longer metabolizing this gas, so are not absorbing this gas through their stomata.
D) Heterocyte walls become less permeable to N2 influx during darkness.
E) The amount of fixed nitrogen that is dissolved in the pond water in which the cyanobacteria are growing peaks at the close of the photosynthetic day (1800 h).

A

Mitochondria are thought to be the descendants of certain alpha-proteobacteria. They are, however, no longer able to lead independent lives because most genes originally present on their chromosome have moved to the nuclear genome. Which phenomenon accounts for the movement of these genes?
A) horizontal gene transfer
B) binary fission
C) alternative gene splicing
D) meiosis
E) plasmolysis

A

Carl Woese and collaborators identified two major branches of prokaryotic evolution. What was the basis for dividing prokaryotes into two domains?
A) microscopic examination of staining characteristics of the cell wall
B) metabolic characteristics such as the production of methane gas
C) metabolic characteristics such as chemoautotrophy and photosynthesis
D) genetic characteristics such as ribosomal RNA sequences
E) ecological characteristics such as the ability to survive in extreme environments

D

Which statement about the domain Archaea is false?
A) Genetic prospecting has recently revealed the existence of many previously unknown archean species.
B) Some archaeans can reduce CO2 to methane.
C) The genomes of archaeans are unique, containing no genes that originated within bacteria.
D) Some archaeans can inhabit solutions that are nearly 30% salt.
E) Some archaeans are adapted to waters with temperatures above the boiling point.

C

If archaeans are more closely related to eukaryotes than to bacteria, then which of the following is a reasonable prediction?
A) Archaean DNA should have no introns.
B) Archaean chromosomes should have no protein bonded to them.
C) Archaean DNA should be single-stranded.
D) Archaean ribosomes should be larger than typical prokaryotic ribosomes.
E) Archaeans should lack cell walls.

D

Which of the following traits do archaeans and bacteria share?
1. composition of the cell wall
2. presence of plasma membrane
3. lack of a nuclear envelope
4. identical rRNA sequences
A) 1 only
B) 3 only
C) 1 and 3
D) 2 and 3
E) 2 and 4

D

Assuming that each of these possesses a cell wall, which prokaryotes should be expected to be most strongly resistant to plasmolysis in hypertonic environments?
A) extreme halophiles
B) extreme thermophiles
C) methanogens
D) cyanobacteria
E) nitrogen-fixing bacteria that live in root nodules

A

The thermoacidophile, Sulfolobus acidocaldarius lacks peptidoglycan. What is likely to be true of this species?
1. It is a bacterium.
2. It is an archaean.
3. The optimal pH of its enzymes will lie above pH 7.
4. The optimal pH of its enzymes will lie below pH 7.
5. It could inhabit certain hydrothermal springs.
6. It could inhabit alkaline hot springs.
A) 1, 3, and 6
B) 2, 4, and 6
C) 2, 4, and 5
D) 1, 3, and 5
E) 1, 4, and 5

C

A fish that had been salt-cured subsequently develops a reddish color. You suspect that the fish has been contaminated by the extreme halophile, Halobacterium. Which of these features of cells removed from the surface of the fish, if confirmed, would support your suspicion?
1. the presence of the same photosynthetic pigments found in cyanobacteria
2. cell walls that lack peptidoglycan
3. cells that are isotonic to conditions on the surface of the fish
4. its cells contain bacteriorhodopsin
5. the presence of very large numbers of ion pumps in its plasma membrane
A) 2 and 5
B) 3 and 4
C) 1, 4, and 5
D) 3, 4, and 5
E) 2, 3, 4, and 5

E

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

D

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

B

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

D

In a hypothetical situation, a bacterium lives on the surface of a leaf, where it obtains nutrition from the leaf's 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

C

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.

E

Foods can be preserved in many ways by slowing or preventing bacterial growth. Which of these methods would not generally inhibit bacterial growth?
A) Refrigeration: Slows bacterial metabolism and growth.
B) Closing previously opened containers: Prevents more bacteria from entering, and excludes O2.
C) Pickling: Creates a pH at which most bacterial enzymes cannot function.
D) Canning in heavy sugar syrup: Creates osmotic conditions that remove water from most bacterial cells.
E) Irradiation: Kills bacteria by mutating their DNA to such an extent that their DNA-repair enzymes are overwhelmed.

B

Many physicians administer antibiotics to patients at the first sign of any disease symptoms. Why can this practice cause more problems for these patients, and for others not yet infected?
A) The antibiotic administered may kill viruses that had been keeping the bacteria in check.
B) Antibiotics may cause other side effects in patients.
C) Overuse of antibiotics can select for antibiotic-resistant strains of bacteria.
D) Particular patients may be allergic to the antibiotic.
E) Antibiotics may interfere with the ability to identify the bacteria present.

C

Broad-spectrum antibiotics inhibit the growth of most intestinal bacteria. Consequently, assuming that nothing is done to counter the reduction of intestinal bacteria, a hospital patient who is receiving broad-spectrum antibiotics is most likely to become
A) unable to fix carbon dioxide.
B) antibiotic resistant.
C) unable to fix nitrogen.
D) unable to synthesize peptidoglycan.
E) deficient in certain vitamins.

E

Which statement about gram-negative bacteria is correct?
A) Penicillins are the best antibiotics to use against them.
B) They often possess an outer membrane containing toxic lipopolysaccharides.
C) Their chromosomes are composed of DNA tightly wrapped around large amounts of histone proteins.
D) Their cell walls are primarily composed of peptidoglycan.

B

Genetic variation in bacterial populations cannot result from
A) transduction.
B) transformation.
C) conjugation.
D) mutation.
E) meiosis.

E

Photoautotrophs use
A) light as an energy source and CO2 as a carbon source.
B) light as an energy source and methane as a carbon source.
C) N2 as an energy source and CO2 as a carbon source.
D) CO2 as both an energy source and a carbon source.
E) H2S as an energy source and CO2 as a carbon source

A

Which of the following statements is not true?
A) Archaea and bacteria have different membrane lipids.
B) Both archaea and bacteria generally lack membrane-enclosed organelles.
C) The cell walls of archaea lack peptidoglycan.
D) Only bacteria have histones associated with DNA.
E) Only some archaea use CO2 to oxidize H2, releasing methane.

D

Which of the following features of prokaryotic biology involves metabolic cooperation among cells?
A) binary fission
B) endospore formation
C) endotoxin release
D) biofilms
E) photoautotrophy

D

Which prokaryotic group is mismatched with its members?
A) Proteobacteriadiverse gram-negative bacteria
B) Gram-positive bacteriasymbionts in legume root nodules
C) Spirocheteshelical heterotrophs
D) Chlamydiasintracellular parasites
E) Cyanobacteriasolitary and colonial photoautotrophs

B

Plant-like photosynthesis that releases O2 occurs in
A) cyanobacteria.
B) chlamydias.
C) archaea.
D) actinomycetes.
E) chemoautotrophic bacteria

A

Protists are alike in that all are
A) unicellular.
B) eukaryotic.
C) symbionts.
D) monophyletic.
E) autotrophic.

B

Biologists have long been aware that the defunct kingdom Protista is paraphyletic. Which of these statements is both true and consistent with this conclusion?
A) Many species within this kingdom were once classified as monerans.
B) Animals, plants, and fungi arose from different protist ancestors.
C) The eukaryotic condition has evolved only once among the protists, and all eukaryotes are descendants of that first eukaryotic cell.
D) Chloroplasts among various protists are similar to those found in prokaryotes.
E) Some protists, all animals, and all fungi share a protist common ancestor, but these protists, animals, and fungi are currently assigned to three different kingdoms

E

The strongest evidence for the endosymbiotic origin of eukaryotic organelles is the similarity between extant prokaryotes and which of the following?
A) nuclei and chloroplasts
B) mitochondria and chloroplasts
C) cilia and mitochondria
D) mitochondria and nuclei
E) mitochondria and cilia

B

According to the endosymbiotic theory of the origin of eukaryotic cells, how did mitochondria originate?
A) from infoldings of the plasma membrane, coupled with mutations of genes for proteins in energy-transfer reactions
B) from engulfed, originally free-living prokaryotes
C) by secondary endosymbiosis
D) from the nuclear envelope folding outward and forming mitochondrial membranes
E) when a protoeukaryote engaged in a symbiotic relationship with a protobiont

B

Which of these statements is false and therefore does not support the hypothesis that certain eukaryotic organelles originated as bacterial endosymbionts? Such organelles
A) are roughly the same size as bacteria.
B) can be cultured on agar, because they make all their own proteins.
C) contain circular DNA molecules.
D) have ribosomes that are similar to those of bacteria.
E) have internal membranes that contain proteins homologous to those of bacterial plasma membranes.

B

Which process allowed the nucleomorphs of chlorarachniophytes to be first reduced, and then (in a few species) lost altogether, without the loss of any genetic information?
A) conjugation
B) horizontal gene transfer
C) binary fission
D) phagocytosis
E) meiosis

B

Which organisms represent the common ancestor of all photosynthetic plastids found in eukaryotes?
A) autotrophic euglenids
B) diatoms
C) dinoflagellates
D) red algae
E) cyanobacteria

E

An individual mixotroph loses its plastids, yet continues to survive. Which of the following most likely accounts for its continued survival?
A) It relies on photosystems that float freely in its cytosol.
B) It must have gained extra mitochondria when it lost its plastids.
C) It engulfs organic material by phagocytosis or by absorption.
D) It has an endospore.
E) It is protected by a siliceous case.

C

Which of these was not derived from an ancestral alpha proteobacterium?
A) chloroplast
B) mitochondrion
C) hydrogenosome
D) mitosome
E) kinetoplast

A

A biologist discovers a new unicellullar organism that possesses more than two flagella and two small, but equal-sized, nuclei. The organism has reduced mitochondria (mitosomes), no chloroplasts, and is anaerobic. To which clade does this organism probably belong?
A) monera
B) the diplomonads
C) the ciliates
D) protista
E) the euglenids

B

Which two genera have members that can evade the human immune system by frequently changing their surface proteins?
1. Plasmodium
2. Trichomonas
3. Paramecium
4. Trypanosoma
5. Entamoeba
A) 1 and 2
B) 1 and 4
C) 2 and 3
D) 2 and 4
E) 4 and 5

B

Which statement regarding resistance is false?
A) Many of the oomycetes that cause potato late blight have become resistant to pesticides.
B) Many of the mosquitoes that transmit malaria to humans have become resistant to pesticides.
C) Many of the malarial parasites have become resistant to antimalarial drugs.
D) Many humans have become resistant to antimalarial drugs.
E) Trichomonas vaginalis is resistant to the normal acidity of the human vagina.

D

Which of these taxa contains species that produce potent toxins that can cause extensive fish kills, contaminate shellfish, and poison humans?
A) red algae
B) dinoflagellates
C) diplomonads
D) euglenids
E) golden algae

B

Which of the following pairs of protists and their characteristics is mismatched?
A) apicomplexans : internal parasites
B) golden algae : planktonic producers
C) euglenozoans : unicellular flagellates
D) ciliates : red tide organisms
E) entamoebas : ingestive heterotrophs

D

Which of these statements about dinoflagellates is false?
A) They possess two flagella.
B) Some cause red tides.
C) Their walls are composed of cellulose plates.
D) Many types contain chlorophyll.
E) Their dead cells accumulate on the seafloor, and are mined to serve as a filtering material.

E

Which group includes members that are important primary producers in ocean food webs, causes red tides that kill many fish, and may even be carnivorous?
A) ciliates
B) apicomplexans
C) dinoflagellates
D) brown algae
E) golden algae

C

You are given an unknown organism to identify. It is unicellular and heterotrophic. It is motile, using many short extensions of the cytoplasm, each featuring the 9+2 filament pattern. It has well-developed organelles and three nuclei, one large and two small. This organism is most likely to be a member of which group?
A) foraminiferans
B) radiolarians
C) ciliates
D) kinetoplastids
E) slime molds

C

Which of the following is not characteristic of ciliates?
A) They use cilia as locomotory structures or as feeding structures.
B) They are relatively complex cells.
C) They can exchange genetic material with other ciliates by the process of mitosis.
D) Most live as solitary cells in fresh water.
E) They have two or more nuclei.

C

Which process results in genetic recombination, but is separate from the process wherein the population size of Paramecium increases?
A) budding
B) meiotic division
C) mitotic division
D) conjugation
E) binary fission

D

Why is the filamentous morphology of the water molds considered a case of convergent evolution with the hyphae (threads) of fungi?
A) Fungi are closely related to the water molds.
B) Body shape reflects ancestor-descendant relationships among organisms.
C) In both cases, filamentous shape is an adaptation for the absorptive nutritional mode of a decomposer.
D) Filamentous body shape is evolutionarily ancestral for all eukaryotes.
E) Both A and B are correct.

C

The Irish potato famine was caused by an organism that belongs to which group?
A) ciliates
B) oomycetes
C) diatoms
D) apicomplexans
E) dinoflagellates

B

If one were to apply the most recent technique used to fight potato late blight to the fight against the malarial infection of humans, then one would
A) increase the dosage of the least-expensive antimalarial drug administered to humans.
B) increase the dosage of the most common pesticide used to kill Anopheles mosquitoes.
C) introduce a predator of the malarial parasite into infected humans.
D) use a "cocktail" of at least three different pesticides against Anopheles mosquitoes.
E) insert genes from a Plasmodium-resistant strain of mosquito into Anopheles mosquitoes.

E

Diatoms are mostly asexual members of the phytoplankton. Diatoms lack any organelles that might have the 9+2 pattern. They obtain their nutrition from functional chloroplasts, and each diatom is encased within two porous, glasslike valves. Which question would be most important for one interested in the day-to-day survival of individual diatoms?
A) How does carbon dioxide get into these protists with their glasslike valves?
B) How do diatoms get transported from one location on the water's surface layers to another location on the surface?
C) How do diatoms with their glasslike valves keep from sinking into poorly lit waters?
D) How do diatoms with their glasslike valves avoid being shattered by the action of waves?
E) How do diatom sperm cells locate diatom egg cells?

C

A large seaweed that floats freely on the surface of deep bodies of water would be expected to lack which of the following?
A) thalli
B) bladders
C) blades
D) holdfasts
E) gel-forming polysaccharides

D

The following are all characteristic of the water molds (oomycetes) except
A) the presence of filamentous feeding structures.
B) flagellated zoospores.
C) a nutritional mode that can result in the decomposition of dead organic matter.
D) a morphological similarity to fungi that is the result of evolutionary convergence.
E) a feeding plasmodium.

E

Water's density and, consequently, its buoyancy decrease at warmer temperatures. Based on this consideration and using data from Table 28.1, at which time of year should one expect diatoms to be storing excess calories mostly as oil?
A) mid-winter
B) early spring
C) late summer
D) late fall

C

Judging from Table 28.1 and given that water's density and, consequently, its buoyancy decrease at warmer temperatures, in which environment should diatoms (and other suspended particles) sink most slowly?
A) cold freshwater
B) warm freshwater
C) cold seawater
D) warm seawater
E) warm brackish water

C

Using dead diatoms to "pump" CO2 to the seafloor is feasible only if dead diatoms sink quickly. Consequently, application of mineral fertilizers, such as iron, should be most effective at times when diatom
A) valves are thickest, and laminarin is being produced rather than oil.
B) valves are thickest, and oil is being produced rather than laminarin.
C) valves are thinnest, and laminarin is being produced rather than oil.
D) valves are thinnest, and oil is being produced rather than laminarin.

A

Theoretically, which two of the following present the richest potential sources of silica?
1. marine sediments consisting of foram tests
2. marine sediments consisting of diatom cases (valves)
3. marine sediments consisting of radiolarian shells
4. marine sediments consisting of dinoflagellate plates
A) 1 and 2
B) 1 and 4
C) 2 and 3
D) 2 and 4
E) 3 and 4

C

Thread-like pseudopods that can perform phagocytosis are generally characteristic of which group?
A) radiolarians and forams
B) gymnamoebas
C) entamoebas
D) amoeboid stage of cellular slime molds
E) oomycetes

A

Which of the following produce the dense glassy ooze found in certain areas of the deep-ocean floor?
A) forams
B) dinoflagellates
C) radiolarians
D) ciliates
E) apicomplexans

C

A snail-like, coiled, porous test (shell) of calcium carbonate is characteristic of which group?
A) diatoms
B) foraminiferans
C) radiolarians
D) gymnamoebas
E) ciliates

B

Typically as cells grow, their increase in volume outpaces their increase in surface area, and continued survival requires undergoing asexual reproduction to reestablish a healthy surface area to volume ratio. Thus, which of these is least likely to contribute to the ability of a single-celled foraminiferan to grow to a diameter of several centimeters?
A) Its threadlike pseudopods dramatically increase its surface area to volume ratio.
B) Its symbiotic algae provide oxygen to the cytoplasm.
C) Its symbiotic algae absorb metabolic waste products from the cytoplasm.
D) Its symbiotic algae provide glucose to the cytoplasm.
E) Its calcium carbonate test contributes extra mass.

E

What makes certain red algae appear red?
A) They live in warm coastal waters.
B) They possess pigments that reflect and transmit red light.
C) They use red light for photosynthesis.
D) They lack chlorophyll.
E) They contain the pigment bacteriorhodopsin.

B

The largest seaweeds belong to which group?
A) red algae
B) green algae
C) brown algae
D) golden algae

C

The chloroplasts of land plants are thought to have been derived according to which evolutionary sequence?
A) cyanobacteria → green algae → land plants
B) cyanobacteria → green algae → fungi → land plants
C) red algae → brown algae → green algae → land plants
D) red algae → cyanobacteria → land plants
E) cyanobacteria → red algae → green algae → land plants

A

The chloroplasts of all of the following are derived from ancestral red algae, except those of
A) golden algae.
B) diatoms.
C) dinoflagellates.
D) green algae.
E) brown algae.

D

A biologist discovers an alga that is marine, multicellular, and lives at a depth reached only by blue light. This alga probably belongs to which group?
A) red algae
B) brown algae
C) green algae
D) dinoflagellates
E) golden algae

A

Green algae often differ from land plants in that some green algae
A) are heterotrophs.
B) are unicellular.
C) have plastids.
D) have alternation of generations.
E) have cell walls containing cellulose.

B

Which taxon of eukaryotic organisms is thought to be directly ancestral to the plant kingdom?
A) golden algae
B) radiolarians
C) foraminiferans
D) apicomplexans
E) green algae

E

If the Archaeplastidae are eventually designated a kingdom, and if the land plants are excluded from this kingdom, then what will be true of this new kingdom?
A) It will be monophyletic.
B) It will more accurately depict evolutionary relationships than does the current taxonomy.
C) It will be paraphyletic.
D) It will be a true clade.
E) It will be polyphyletic.

C

The best evidence for not classifying the slime molds as fungi comes from slime molds'
A) DNA sequences.
B) nutritional modes.
C) choice of habitats.
D) physical appearance.
E) reproductive methods.

A

Which pair of alternatives is highlighted by the life cycle of the cellular slime molds, such as Dictyostelium?
A) prokaryotic or eukaryotic
B) plant or animal
C) unicellular or multicellular
D) diploid or haploid
E) autotroph or heterotroph

C

Which of the following correctly pairs a protist with one of its characteristics?
A) diplomonads : micronuclei involved in conjugation
B) ciliates : pseudopods
C) apicomplexans : parasitic
D) gymnamoebas : calcium carbonate test
E) foraminiferans : abundant in soils

C

Which of the following statements concerning protists is false?
A) All protists are eukaryotic organisms; many are unicellular or colonial.
B) The primary organism that transmits malaria to humans by its bite is the tsetse fly.
C) All apicomplexans are parasitic.
D) Cellular slime molds have an amoeboid stage that may be followed by a stage during which spores are produced.
E) Euglenozoans that are mixotrophic contain chloroplasts.

B

Which of the following is correctly described as a primary producer?
A) oomycete
B) kinetoplastid
C) apicomplexan
D) diatom
E) radiolarian

D

A certain unicellular eukaryote has a siliceous (glasslike) shell and autotrophic nutrition. To which group does it belong?
A) dinoflagellates
B) diatoms
C) brown algae
D) radiolarians
E) oomycetes

B

You are given the task of designing an aerobic, mixotrophic protist that can perform photosynthesis in fairly deep water (e.g., 250 m deep), and can also crawl about and engulf small particles. With which two of these structures would you provide your protist?
1. hydrogenosome
2. apicoplast
3. pseudopods
4. chloroplast from red alga
5. chloroplast from green alga
A) 1 and 2
B) 2 and 3
C) 2 and 4
D) 3 and 4
E) 4 and 5

D

You are given the task of designing an aquatic protist that is a primary producer. It cannot swim on its own, yet must stay in well-lit surface waters. It must be resistant to physical damage from wave action. It should be most similar to a(n)
A) diatom.
B) dinoflagellate.
C) apicomplexan.
D) red alga.
E) radiolarian

A

) Some protists, formerly united as the "amitochondriate" clade, have recently been shown to be rather diverse. Some of them possess neither mitochondria nor mitochondrial genes (and have been classified as fungi). Others possess no mitochondria, but do have mitochondrial genes in their nuclear genome. Still others have modified mitochondria (viz. mitosomes or hydrogenosomes). Which statement(s) represent(s) consequences of these recent findings?
1. The amitochondriates do not comprise a true clade.
2. The "amitochondriate hypothesis" concerning the root of the eukaryotic tree has been strengthened.
3. Just as there is a diversity of cyanobacterial descendants among eukaryotes, so too is there a diversity of alpha-proteobacterial descendants among the eukaryotes.
4. If the amitochondriate organisms continued to be recognized as a taxon, this taxon would be polyphyletic.
5. Horizontal gene transfer involving mitochondrial genes has occurred in some amitochondriate organisms.
A) 1 only
B) 1 and 4
C) 2 and 3
D) 1, 3, and 5
E) all except 2

E

Similar to most amoebozoans, the forams and the radiolarians also have pseudopods, as do the white blood cells of animals. If one were to erect a taxon that included all organisms that have cells with pseudpods, what would be true of such a taxon?
A) It would be polyphyletic.
B) It would be paraphyletic.
C) It would be monophyletic.
D) It would include all eukaryotes

A

You are designing an artificial drug-delivery "cell" that can penetrate animal cells. Which of these protist structures should provide the most likely avenue for research along these lines?
A) pseudopods
B) apical complex
C) excavated feeding grooves
D) nucleomorphs
E) mitosomes

B

A gelatinous seaweed that grows in shallow, cold water and undergoes heteromorphic alternation of generations is most probably what type of alga?
A) red
B) green
C) brown
D) yellow

C

Which of these are actual mutualistic partnerships that involve a protist and a host organism?
A) cellulose-digesting gut protists : wood-eating termites
B) dinoflagellates : reef-building coral animals
C) Trichomonas : humans
D) algae : certain foraminiferans
E) all except C

E

Which of the following statements concerning living phytoplanktonic organisms are true?
1. They are important members of communities surrounding deep-sea hydrothermal vents.
2. They are important primary producers in most aquatic food webs.
3. They are important in maintaining oxygen in Earth's seas and atmosphere.
4. They are most often found growing in the sediments of seas and oceans.
5. They can be so concentrated that they affect the color of seawater.
A) 1 and 4
B) 1, 2, and 4
C) 2, 3, and 4
D) 2, 3, and 5
E) 3, 4, and 5

D

Which term most accurately describes the nutritional mode of healthy P. bursaria?
A) photoautotroph
B) photoheterotroph
C) chemoheterotroph
D) chemoautotroph
E) mixotroph

E

Which term accurately describes the behavior of Paramecium species that lack zoochlorellae in an aquarium with light coming from one side only?
A) positive chemotaxis
B) negative chemotaxis
C) positive phototaxis
D) negative phototaxis

D

Which term best describes the symbiotic relationship of well-fed P. bursaria to their zoochlorellae?
A) mutualistic
B) commensal
C) parasitic
D) predatory
E) pathogenic

A

If both host and alga can survive apart from each other, then which of these best accounts for their ability to live together?
A) genome fusion
B) horizontal gene transfer
C) genetic recombination
D) conjugation
E) metabolic cooperation

E

The motility that permits P. bursaria to move toward a light source is provided by
A) pseudopods.
B) a single flagellum composed of the protein, flagellin.
C) a single flagellum featuring the 9+2 pattern.
D) many cilia.
E) contractile vacuoles.

D

If the chloroplasts of the zoochlorellae are very similar to those found in the photosynthetic cells of land plants, then Chlorella is probably what type of alga?
A) red
B) green
C) brown
D) golden

B

A P. bursaria cell that has lost its zoochlorellae is said to be "aposymbiotic." It might be able to replenish its contingent of zoochlorellae by ingesting them without subsequently digesting them. Which of these situations would be most favorable to the re-establishment of resident zoochlorellae, assuming compatible Chlorella are present in P. bursaria's habitat?
A) abundant light, no bacterial prey
B) abundant light, abundant bacterial prey
C) no light, no bacterial prey
D) no light, abundant bacterial prey

B

A P. bursaria cell that has lost its zoochlorellae is "aposymbiotic." If aposymbiotic cells have population growth rates the same as those of healthy, zoochlorella-containing P. bursaria in well-lit environments with plenty of prey items, then such an observation would be consistent with which type of relationship?
A) parasitic
B) commensalistic
C) toxic
D) predator-prey
E) mutualistic

B

Theoretically, P.bursaria can obtain zoochlorella either vertically (via the asexual reproduction of its mother cell) or horizontally (by ingesting free-living Chlorella from its habitat). Consider a P. bursaria cell containing zoochlorellae, but whose habitat lacks free-living Chlorella. If this cell subsequently undergoes many generations of asexual reproduction, if all of its daughter cells contain roughly the same number of zoochlorellae as it had originally contained, and if the zoochlorellae are all haploid and identical in appearance, then what is true?
A) The zoochlorellae also reproduced asexually, at an increasing rate over time.
B) The zoochlorellae also reproduced asexually, at a decreasing rate over time.
C) The zoochlorellae also reproduced asexually, at a fairly constant rate over time.
D) The zoochlorellae reproduced sexually, undergoing heteromorphic alternation of generations.
E) The zoochlorellae reproduced sexually, undergoing isomorphic alternation of generations.

C

Can P. bursaria live in association with any and all strains/species of Chlorella? In an experiment to help answer this question, Chlorella was collected, and cultured separately, from three different sources: (1) P. bursaria cytoplasm, (2) free-living Chlorella, and (3) from cytoplasm of other protist species. A population of P. bursaria was treated with the herbicide, paraquat, which killed all of its zoochlorellae, but otherwise left P. bursaria unharmed. The zoochlorella-free paramecia were then introduced to a 1:1:1 mixture of Chlorella from the three cultures listed above, and subsequently reestablished a contingent of zooclorellae. Two weeks later, zoochlorellae were collected from the P. bursaria cells and tested to determine which Chlorella strain(s) had been maintained within P. bursaria. The different strains of Chlorella are morphologically indistinguishable. Consequently, which of these would be the best test to perform on Chlorella, both before and after re-establishment of zoochlorellae, to determine which Chlorella strains had been maintained within P. bursaria?
A) Determine the chemical composition of its cell wall.
B) Determine the absorption spectrum of its photosynthetic pigments.
C) Determine the sequence of a portion of its mitochondrial DNA.
D) Determine the sequence of an exon of a ribosomal RNA gene.
E) Determine the endosymbiont's diameter.

C

Which conclusion is consistent with the data presented in Figure 28.2 above?
A) Co-adaptation between P. bursaria and the native strain of Chlorella has occurred.
B) All types of Chlorella tested are tolerated equally well by P. bursaria.
C) P. bursaria cannot reproduce in the absence of zoochlorellae as well as it can when zoochlorellae are present.
D) Zoochlorellae derived from other protists are well adapted to survive within P. bursaria, relative to the native strain.

A

Which of these precautions would have been most important to insuring the validity of the results?
A) Chlorella in the three cultures were genetically identical.
B) Roughly equal numbers of each strain of Chlorella were present in the reintroduction mixture.
C) The Chlorella cultures were free of bacteria.
D) The P. bursaria culture was free of bacteria.
E) The Chlorella DNA contained no introns.

B

Is P. bursaria's ability to detect and move toward light an innate ability, or is it due to the presence of zoochlorellae? Arrange the following steps in the proper sequence needed to answer this question.
1. Introduce P. bursaria from both the experimental and control populations to an aquarium that lacks free-living Chlorella, but that contains bacterial prey.
2. Remove equal amounts of water from the well-lit side of the aquarium and the poorly lit side of the aquarium, census the number and kind of P. bursaria present in each sample.
3. Shine light on only one side of the aquarium containing aposymbiotic P. bursaria.
4. Expose one population of P. bursaria (the experimental population) to an herbicide to kill its zoochlorellae.
5. Collect healthy P. bursaria from the well-lit side of an aquarium and divide it into two equal populations: a control population and an experimental population.
A) 5 → 4 → 1 → 2 → 3
B) 5 → 4 → 1 → 3 → 2
C) 4 → 1 → 5 → 3 → 2
D) 2 → 5 → 4 → 1 → 3
E) 2 → 5 → 4 → 3 → 1

B

Plastids that are surrounded by more than two membranes are evidence of
A) evolution from mitochondria.
B) fusion of plastids.
C) origin of the plastids from archaea.
D) secondary endosymbiosis.
E) budding of the plastids from the nuclear envelope.

D

Biologists suspect that endosymbiosis gave rise to mitochondria before plastids partly because
A) the products of photosynthesis could not be metabolized without mitochondrial enzymes.
B) all eukaryotes have mitochondria (or their remnants), whereas many eukaryotes do not have plastids.
C) mitochondrial DNA is less similar to prokaryotic DNA than is plastid DNA.
D) without mitochondrial CO2 production, photosynthesis could not occur.
E) mitochondrial proteins are synthesized on cytosolic ribosomes, whereas plastids utilize their own ribosomes.

B

Which group is incorrectly paired with its description?
A) rhizarians-morphologically diverse group defined by DNA similarities
B) diatoms-important producers in aquatic communities
C) red algae-acquired plastids by secondary endosymbiosis
D) apicomplexans-parasites with intricate life cycles
E) diplomonads-protists with modified mitochondria

C

Based on the phylogenetic tree in Figure 28.3 in the text, which of the following statements is correct?
A) The most recent common ancestor of Excavata is older than that of Chromalveolata.
B) The most recent common ancestor of Chromalveolata is older than that of Rhizaria.
C) The most recent common ancestor of red algae and land plants is older than that of nucleariids and fungi.
D) The most basal (first to diverge) eukaryotic supergroup cannot be determined.
E) Excavata is the most basal eukaryotic supergroup.

C

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