5) The first terrestrial organisms probably were considered which of the following?

1. burrowers

2. photosynthetic

3. multicellular

4. prokaryotes

5. eukaryotes

6. plants and their associated fungi

A) 2 and 4

B) 3 and 5

C) 1, 3, and 5

D) 2, 3, and 6

E) 2, 3, 5, and 6

A

The evolution of mammals from early tetrapods

A) is well documented by a series of transitional fossils.

B) involves specialization in teeth.

C) involves changes in the temporal fenestra of the skull.

D) is an example of macroevolution.

E) All of the above statements are true.

D

If two continents converge and are united, then the collision should cause

A) a net loss of intertidal zone and coastal habitat.

B) the extinction of any species adapted to intertidal and coastal habitats.

C) an overall decrease in the surface area located in the continental interior.

D) a decrease in climatic extremes in the interior of the new supercontinent.

E) the maintenance of the previously existing ocean currents and wind patterns.

A

The major evolutionary episode corresponding most closely in time with the formation of Pangaea was the

A) Cambrian explosion.

B) Permian extinctions.

C) Pleistocene ice ages.

D) Cretaceous extinctions.

B

9) An organism has a relatively large number of Hox genes in its genome. Which of the following is true of this organism?

A) These genes are fundamental, and are expressed in all cells of the organism.

B) The organism must have multiple paired appendages along the length of its body.

C) The organism has the genetic potential to have a relatively complex anatomy.

D) Most of its Hox genes owe their existence to gene fusion events.

E) Its Hox genes cooperate to bring about sexual maturity at the proper stage of development.

C

10) Bagworm moth caterpillars feed on evergreens and carry a silken case or bag around with them in which they eventually pupate. Adult female bagworm moths are larval in appearance; they lack the wings and other structures of the adult male and instead retain the appearance of a caterpillar even though they are sexually mature and can lay eggs within the bag. This is a good example of

A) allometric growth.

B) paedomorphosis.

C) sympatric speciation.

D) adaptive radiation.

E) changes in homeotic genes

B

The loss of ventral spines by modern freshwater sticklebacks is due to natural selection operating on the phenotypic effects of Pitx1 gene

A) duplication (gain in number).

B) elimination (loss).

C) mutation (change).

D) silencing (loss of expression).

D

12) Larval flies (maggots) express the Ubx gene in all of their segments, and thereby lack appendages. If this same gene continued to be expressed throughout subsequent developmental stages, except in the head region, and if the result was a fit, sexually mature organism that still strongly resembled a maggot, this would be an example of

A) exaptation.

B) homochrony.

C) paedomorphosis.

D) adaptive radiation.

C

13) The existence of the phenomenon of exaptation is most closely associated with which of the following observations that natural selection cannot fashion perfect organisms?

A) Natural selection and sexual selection can work at cross-purposes to each other.

B) Evolution is limited by historical constraints.

C) Adaptations are often compromises.

D) Chance events affect the evolutionary history of populations in environments that can change unpredictably.

B

14) One explanation for the evolution of insect wings suggests that wings began as lateral extensions of the body that were used as heat dissipaters for thermoregulation. When they had become sufficiently large, these extensions became useful for gliding through the air, and selection later refined them as flight-producing wings. If this hypothesis is correct, modern insect wings could best be described as

A) adaptations.

B) mutations.

C) exaptations.

D) isolating mechanisms.

E) examples of natural selection's predictive ability.

C

Many species of snakes lay eggs. However, in the forests of northern Minnesota where growing seasons are short, only live-bearing snake species are present. This trend toward species that perform live birth in a particular environment is an example of

A) natural selection.

B) sexual selection.

C) species selection.

D) goal direction in evolution.

E) directed selection.

C

16) In the 5 to 7 million years that the hominid lineage has been diverging from its common ancestor with the great apes, dozens of hominid species have arisen, often with several species coexisting in time and space. As recently as 30,000 years ago, Homo sapiens coexisted with Homo neanderthalensis. Both species had large brains and advanced intellects. The fact that these traits were common to both species is most easily explained by which of the following?

A) species selection

B) uniformitarianism

C) sexual selection

D) convergent evolution

A

The existence of evolutionary trends, such as increasing body sizes among horse species, is evidence that

A) a larger volume-to-surface area ratio is beneficial to all mammals.

B) an unseen guiding force is at work.

C) evolution always tends toward increased complexity or increased size.

D) in particular environments, similar adaptations can be beneficial in more than one species.

E) evolution generally progresses toward some predetermined goal

D

18) Fossil evidence indicates that several kinds of flightless dinosaurs possessed feathers. If some of these feather-bearing dinosaurs incubated clutches of eggs in carefully constructed nests, this might be evidence supporting the claim that

A) dinosaurs were as fully endothermal (warm-blooded) as modern birds and mammals.

B) their feathers originally served as insulation, and only later became flight surfaces.

C) the earliest reptiles could fly, and the feathers of flightless dinosaurs were vestigial flight surfaces.

D) the feathers were plucked from the bodies of other adults to provide

B

Figure 23.1 represents a cross section of the sea floor through a mid-ocean rift valley, with alternating patches of black and white indicating sea floor with reversed magnetic polarities. At the arrow labeled "I" (the rift valley), the igneous rock of the sea floor is so young that it can be accurately dated using carbon-14 dating. At the arrow labeled "III," however, the igneous rock is about 1 million years old, and potassium-40 dating is typically used to date such rocks. Note:The horizontal arrows indicate the direction of sea-floor spreading, away from the rift valley.

Figure 23.1

1) Assuming that the rate of sea-floor spreading was constant during the 1-million-year period depicted in Figure 23.1, on average Earth's magnetic field has undergone reversal once every

A) 10,000 years.

B) 25,000 years.

C) 100,000 years.

D) 250,000 years.

E) 1,000,000 years.

D

2) Which section of sea-floor crust should have the thickest layer of overlying sediment, assuming a continuous rate of sediment deposition?

A) A

B) B

C) C

D) D

E) E

E

If a particular marine organism is fossilized in the sediments immediately overlying the igneous rock at the arrow labeled "II," at which other location(s), labeled A-E, would a search be most likely to find more fossils of this organism?

A) B only

B) C only

C) D only

D) B and C

E) C and D

B

How many other bands of sea-floor crust in Figure 23.1 have the same magnetic polarity as the crust that directly straddles the rift valley?

A) 2 bands

B) 4 bands

C) 6 bands

D) 8 bands

E) 10 bands

B

Assuming that the rate of sea-floor spreading was constant during the 1-million-year period depicted in Figure 23.1, what should be the approximate age of marine fossils found in undisturbed sedimentary rock immediately overlying the igneous rock at the arrow labeled "II"?

A) 10,000 years

B) 250,000 years

C) 500,000 years

D) 1,000,000 years

C

and on, throughout the entire time that terrestrial life has existed. Researchers wish to locate and study the terrestrial organisms fossilized in this core. The core is illustrated as a vertical column, with the top of the column representing the most recent strata and the bottom representing the time when land was first colonized by life.

6) Assuming the existence of fossilized markers for each of the following chemicals, what is the sequence in which they should be found in this sediment core, working from ancient sediments to recent sediments?

1. chitin coupled with protein

2. chlorophyll

3. bone

4. cellulose

A) 2, 4, 3, 1

B) 2, 4, 1, 3

C) 4, 2, 1, 3

D) 4, 2, 3, 1

B

23.3

7) Hawaii is the most southeastern of the seven islands and is also closest to the sea-floor spreading center from which the Pacific plate originates, which lies about 5,600 km further to the southeast. Assuming equal sedimentation rates, what should be the location of the thickest sediment layer and, thus, the area with the greatest diversity of fossils above the oceanic crust?

A) between the island of Hawaii and the sea-floor spreading center

B) around the base of the island of Hawaii

C) around the base of Kauai, the oldest of the Hawaiian islands

D) where the islands are most concentrated (highest number of islands per unit surface area)

C

According to the theory of sea-floor spreading, oceanic islands, such as the Hawaiian Islands depicted in Figure 23.3, form as oceanic crustal plates move over a stationary "hot spot" in the mantle. Currently, the big island of Hawaii is thought to be over a hot spot, which is why it is the only one of the seven islands that has active volcanoes. What should be true of the island of Hawaii?

1. Scientists in search of ongoing speciation events are more likely to find them here than on the other six islands.

2. Its species should be more closely related to those of nearer islands than to those of farther islands.

3. It should have a rich fossil record of terrestrial organisms.

4. There is a good chance of finding endemic species on this island.

5. On average, it should have fewer species per unit surface area than the other six islands.

A) 1, 2, and 3

B) 1, 2, and 5

C) 1, 2, 3, and 4

D) 1, 2, 4, and 5

E) 2, 3, 4, and 5

D

9) Upon being formed, oceanic islands, such as the Hawaiian Islands, should feature what characteristic, leading to which phenomenon?

A) mass extinctions, leading to bottleneck effect

B) major evolutionary innovations, leading to rafting to nearby continents

C) a variety of empty ecological niches, leading to adaptive radiation

D) adaptive radiation, leading to founder effect

E) overcrowding, leading to rafting to nearby lands

C

1) In each fly species, the entire body segment that gave rise to the original flight wings is missing. The mutation(s) that led to the flightless condition could have

A) duplicated all of the Hox genes in these flies' genomes.

B) altered the nucleotide sequence within a Hox gene.

C) altered the expression of a Hox gene.

D) all three of the responses are correct.

E) two of the responses are correct.

E

2) If these fly species lost the ability to fly independently of each other as a result of separate mutation events in each lineage, then the flightless condition in these species could be an example of

A) adaptive radiation.

B) species selection.

C) sexual selection.

D) allometric growth.

E) habitat differentiation.

B

3) Which of these fly organs, as they exist in current fly populations, best fits the description of an exaptation?

A) wings

B) balancing organs

C) mouthparts

D) thoraxes

E) walking appendages

B

Fruit fly eyes are of the compound type, which is structurally very different from the camera-type eyes of mammals. Even the camera-type eyes of molluscs, such as octopi, are structurally quite different from those of mammals. Yet, fruit flies, octopi, and mammals possess very similar versions of Pax-6. The fact that the same gene helps produce very different types of eyes is most likely due to

A) the few differences in nucleotide sequence among the Pax-6 genes of these organisms.

B) variations in the number of Pax-6 genes among these organisms.

C) the independent evolution of this gene at many different times during animal evolution.

D) differences in the control of Pax-6 expression among these organisms

D

5) Pax-6 usually causes the production of a type of light-receptor pigment. In vertebrate eyes, though, a different gene (the rh gene family) is responsible for the light-receptor pigments of the retina. The rh gene, like Pax-6, is ancient. In the marine ragworm, for example, the rh gene causes production of c-opsin, which helps regulate the worm's biological clock. Which of these most likely accounts for vertebrate vision?

A) The Pax-6 gene mutated to become the rh gene among early mammals.

B) During vertebrate evolution, the rh gene for biological clock opsin was co-opted as a gene for visual receptor pigments.

C) In animals more ancient than ragworms, the rh gene(s) coded for visual receptor pigments; in lineages more recent than ragworms, rh has flip-flopped several times between producing biological clock opsins and visual receptor pigments.

D) Pax-6 was lost from the mammalian genome, and replaced by the rh gene much later.

B

The appearance of Pax-6 in all animals with eyes can be explained in multiple ways. Based on the information, which explanation is most likely?

A) Pax-6 in all of these animals is not homologous; it arose independently in many different animal phyla due to intense selective pressure favoring vision.

B) The Pax-6 gene is really not "one" gene. It is many different genes that, over evolutionary time and due to convergence, have come to have a similar nucleotide sequence and function.

C) The Pax-6 gene was an innovation of an ancestral animal of the early Cambrian period. Animals with eyes or eyespots are descendants of this ancestor.

D) The perfectly designed Pax-6 gene appeared instantaneously in all animals created to have eyes or eyespots.

C

Which factor most likely caused animals and plants in India to differ greatly from species in nearby Southeast Asia?

A) The species became separated by convergent evolution.

B) The climates of the two regions are similar.

C) India is in the process of separating from the rest of Asia.

D) Life in India was wiped out by ancient volcanic eruptions.

E) India was a separate continent until 45 million years ago

E

2) Adaptive radiations can be a direct consequence of four of the following five factors. Select the exception.

A) vacant ecological niches

B) genetic drift

C) colonization of an isolated region that contains suitable habitat and few competitor species

D) evolutionary innovation

E) an adaptive radiation in a group of organisms (such as plants) that another group uses as foodA

B

researcher discovers a fossil of what appears to be one of the oldest-known multicellular organisms. The researcher could estimate the age of this fossil based on

A) the amount of carbon-14 in the fossil.

B) the amount of uranium-238 in the fossil.

C) the amount of carbon-14 in the sedimentary rocks in which the fossil was found.

D) the amount of uranium-238 in volcanic layers surrounding the fossil.

E) the amount of uranium-238 in the sedimentary rocks in which the fossil was found.

D

A genetic change that caused a certain Hox gene to be expressed along the tip of a vertebrate limb bud instead of farther back helped make possible the evolution of the tetrapod limb. This type of change is illustrative of

A) the influence of environment on development.

B) paedomorphosis.

C) a change in a developmental gene or in its regulation that altered the spatial organization of body parts.

D) heterochrony.

E) gene duplication.

C

A swim bladder is a gas-filled sac that helps fish maintain buoyancy. The evolution of the swim bladder from the air-breathing organ (a simple lung) of an ancestral fish is an example of

A) an evolutionary trend.

B) exaptation.

C) changes in Hox gene expression.

D) paedomorphosis.

E) adaptive radiation.

B

1) Foods can be preserved in many ways by slowing or preventing bacterial growth. Which of these methods should be least effective at inhibiting 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

2) How were conditions on the early Earth of more than 3 billion years ago different from those on today's Earth?

A) Only early Earth was intensely bombarded by large space debris.

B) Only early Earth had an oxidizing atmosphere.

C) Less ultraviolet radiation penetrated early Earth's atmosphere.

D) Early Earth's atmosphere had significant quantities of ozone.

A

3) What is true of the amino acids that might have been delivered to Earth within carbonaceous chondrites?

A) They had the same proportion of L and D isomers as Earth does today.

B) Their abundance would have been dramatically reduced upon passage through early Earth's oxidizing atmosphere.

C) There were more kinds of amino acids on the chondrites than are found in living organisms today.

D) They were delivered in the form of polypeptides.

C

4) Which of the following is the correct sequence of events in the origin of life?

I. ​formation of protobionts

II. ​synthesis of organic monomers

III. ​synthesis of organic polymers

IV. ​formation of DNA-based genetic systems

A) I, II, III, IV

B) I, III, II, IV

C) II, III, I, IV

D) II, III, IV, I

C

Which of the following is a defining characteristic that all protobionts had in common?

A) the ability to synthesize enzymes

B) a surrounding membrane or membrane-like structure

C) RNA genes

D) the ability to replicate RNA

B

The first genes on Earth were probably

A) DNA produced by reverse transcriptase from abiotically produced RNA.

B) DNA molecules whose information was transcribed to RNA and later translated in polypeptides.

C) auto-catalytic RNA molecules.

D) oligopeptides located within protobionts.

C

The synthesis of new DNA requires the prior existence of oligonucleotides to serve as primers. On Earth, these primers are small RNA molecules. This latter observation is evidence in support of the hypothesized existence of

A) a snowball Earth.

B) earlier genetic systems than those based on DNA.

C) the abiotic synthesis of organic monomers.

D) the delivery of organic matter to Earth by meteors and comets.

E) the endosymbiotic origin of mitochondria and chloroplasts.

B

Several scientific laboratories across the globe are involved in research concerning the origin of life on Earth. Which of these questions is currently the most problematic and would have the greatest impact on our understanding if we were able to answer it?

A) How can amino acids, simple sugars, and nucleotides be synthesized abiotically?

B) How can RNA molecules catalyze reactions?

C) How did RNA sequences come to carry the code for amino acid sequences?

D) How could polymers involving lipids and/or proteins form membranes in aqueous environments?

E) How can RNA molecules act as templates for the synthesis of complementary RNA molecules?

C

9) Approximately how far back in time does the fossil record extend?

A) 3.5 million years

B) 5.0 million years

C) 3.5 billion years

D) 5.0 billion years

C

10) Which of the following statements provides the strongest evidence that prokaryotes evolved before eukaryotes?

A) Prokaryotic cells lack nuclei.

B) The meteorites that have struck Earth contain fossils only of prokaryotes.

C) Laboratory experiments have produced liposomes abiotically.

D) Liposomes closely resemble prokaryotic cells.

E) The oldest fossilized cells resemble prokaryotes.

E

11) If it were possible to conduct sophisticated microscopic and chemical analyses of microfossils found in 3.2-billion-year-old stromatolites, then one should be surprised to observe evidence of which of the following within such microfossils?

I. ​double-stranded DNA

II. ​a nuclear envelope

III. ​a nucleoid

IV. ​a nucleolus

V. ​ribosomes

A) II only

B) III only

C) II and IV

D) II, III, and IV

E) all five of these

C

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

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, 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

14) Jams, jellies, preserves, honey, and other foodstuffs with 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 as a result of water loss from the cell.

B) are unable to metabolize the glucose or fructose, and thus starve to death.

C) experience lysis.

D) are obligate anaerobes.

E) are unable to swim through these thick and viscous materials

A

15) 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 structure(s)?

1. nucleoid region

2. endospore

3. fimbriae

4. plasmids

A) 1 only

B) 1 and 2 only

C) 1 and 4 only

D) 2 and 4 only

E) 1, 2, and 4

E

16) 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

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.

E) a membrane-enclosed organelle with motor proteins

C

Prokaryotic ribosomes differ from those present in eukaryotic cytosol. Because of this, which of the following is correct?

A) Some antibiotics can block protein synthesis in bacteria without effects 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 unable to use a greater variety of molecules as food sources than can eukaryotes.

A

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 nucleolus.

E) Prokaryotic genomes are composed of circular DNA.

E

20) 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 also

A) lack antibiotic-resistant genes.

B) lack a cell wall.

C) lack a chromosome.

D) lack water in its cytoplasm.

E) be unable to survive in its normal environment

A

21) Prokaryotes' essential genetic information is located in the

A) nucleolus.

B) nucleoid.

C) nucleosome.

D) plasmids.

E) exospore.

B

Chloramphenicol is an antibiotic that targets prokaryotic (70S) ribosomes, but not eukaryotic (80S) ribosomes. Which of these questions stems from this observation, plus an understanding of eukaryotic origins?

A) Can chloramphenicol also be used to control human diseases that are caused by archaeans?

B) Can chloramphenicol pass through the capsules possessed by many cyanobacteria?

C) If chloramphenicol inhibits prokaryotic ribosomes, should it not also inhibit mitochondrial ribosomes?

D) Why aren't prokaryotic ribosomes identical to eukaryotic ribosomes?

E) How is translation affected in ribosomes that are targeted by chloramphenicol?

C

Match the numbered terms to the description that follows. Choose all appropriate terms.

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

Match the numbered terms to the description that follows. Choose all appropriate terms.

1. autotroph

2. heterotroph

3. phototroph

4. chemotroph

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

Match the numbered terms to the description that follows. Choose all appropriate terms.

1. autotroph

2. heterotroph

3. phototroph

4. chemotroph

an organism that obtains energy from light

A) 1 only

B) 3 only

C) 1 and 3

D) 2 and 4

E) 1, 3, and 4

B

Which of the following obtain energy by oxidizing inorganic substances to obtain energy that is used, in part, to fix CO2?

A) photoautotrophs

B) photoheterotrophs

C) chemoautotrophs

D) chemoheterotrophs that perform decomposition

E) parasitic chemoheterotrophs

C

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 bacterium that has undergone transduction.

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.

B

Although not present in all bacteria, this cell covering often enables cells that possess it to resist the defenses of host organisms, especially their phagocytic cells.

A) endospore

B) sex pilus

C) cell wall

D) capsule

D

Regarding prokaryotic genetics, which statement is correct?

A) Crossing over during prophase I introduces some genetic variation.

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

Which of these statements about prokaryotes is correct?

A) Bacterial cells conjugate to mutually exchange genetic material.

B) Their genetic material is confined within vesicles known as plasmids.

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

D) The persistence of bacteria throughout evolutionary time is due to their genetic homogeneity (in other words, sameness).

E) Genetic variation in bacteria is not known to occur, because of their asexual mode of reproduction.

C

Which of the following is least associated with the others?

A) horizontal gene transfer

B) genetic recombination

C) conjugation

D) transformation

E) binary fission

E

In Fred Griffith's experiments, harmless R strain pneumococcus became lethal S strain pneumococcus as the result of which of the following?

1. horizontal gene transfer

2. transduction

3. conjugation

4. transformation

5. genetic recombination

A) 2 only

B) 4 only

C) 2 and 5

D) 1, 3, and 5

E) 1, 4, and 5

E

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) plasmolysis

B) conjugation

C) translation

D) endocytosis

E) horizontal gene transfer

E

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

35) Which statement about the domain Archaea is true?

A) Genetic prospecting has recently revealed the existence of many previously unknown archaean species.

B) No archaeans can reduce CO2 to methane.

C) The genomes of archaeans are unique, containing no genes that originated within bacteria.

D) No archaeans can inhabit solutions that are nearly 30% salt.

E) No archaeans are adapted to waters with temperatures above the boiling point.

A

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

38) 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, but still possesses a cell wall. 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 has 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. cells unable to survive salt concentrations lower than 9%

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

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 should contain less cellulose than do bacteria that possess cell walls.

E) They possess typical prokaryotic flagella.

B

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

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 of the following terms 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) 2, 3, and 4

D

In general, 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

45) 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, however, 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. pathogen

5. primary producer

A) 1, 3, 4

B) 2, 3, 4

C) 2, 4, 1

D) 1, 2, 5

E) 1, 2, 3

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 and nutrients.

E

1) Several scientific laboratories across the globe are performing research concerning the origin of life on Earth. Given our current understanding of Earth's first genetic systems, which of the following results would you predict would be obtained in abiotic experiments testing the potential for hydrogen bonding between various nucleic acids and amino acids?

A)

B)

C)

D)

B

In this eight-year experiment, 12 populations of E. coli, each begun from a single cell, were grown in low-glucose conditions for 20,000 generations. Each culture was introduced to fresh growth medium every 24 hours. Occasionally, samples were removed from the populations, and their fitness in low-glucose conditions was tested against that of members sampled from the ancestral (common ancestor) E. coli population.

Figure 24.1

2) Which term best describes what has occurred among the experimental populations of cells over this eight-year period?

A) microevolution

B) speciation

C) adaptive radiation

D) sexual selection

E) stabilizing selection

A

Which of the following, if it occurs in the absence of any other type of adaptation listed here, 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

) If the vertical axis of Figure 24.1 refers to "Darwinian fitness," then which of the following 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

) 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

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

7) If the experimental population of E. coli lacks an F factor or F plasmid, and if bacteriophages are excluded from the bacterial cultures, then which of these is (are) 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) Two of the responses above are correct.

D

8) 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

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) Its membrane-bound DNA pumps are inactive.

C

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

A) 1 and 2

B) 1 and 4

C) 2 and 3

D) 2 and 4

E) 3 and 4

C

During which two times can the recipient accurately be described as "recombinant" due to the sequence of events portrayed in Figure 24.2?

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

Which question, arising from the results depicted in Figure 24.2, 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) What forces are generally responsible for disrupting the sex pilus?

C) How is it that a recipient cell does not necessarily become an Hfr cell as the result of conjugation with an Hfr cell?

D) What makes a cell an Hfr cell?

A

The data were collected from the heterocysts of a nitrogen-fixing cyanobacterium inhabiting equatorial ponds. Study the graph in Figure 24.3 and choose the most likely explanation for the shape of the curve.

Figure 24.3

A) Enough O2 enters heterocysts during hours of peak photosynthesis to have a somewhat-inhibitory effect 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 they are not absorbing this gas through their stomata.

D) Heterocyst 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 hours).

A

24.1

14) Which two species should have much more phospholipid, in the form of bilayers, in their cytoplasm than most other bacteria?

A) species A and B

B) species A and C

C) species B and E

D) species C and D

E) species C and E

C

15) Which species should be able to respond most readily to taxes (plural of taxis)?

A) species A

B) species B

C) species C

D) species D

E) species E

C

How many of these species probably have a cell wall that partly consists of an outer membrane of lipopolysaccharide?

A) only one species

B) two species

C) three species

D) four species

E) all five species

C

Gram-variable prokaryotes are, sometimes, those without any peptidoglycan. Which twospecies are most likely to be archaeans?

A) species A and B

B) species A and C

C) species B and E

D) species C and D

E) species C and E

A

Species D is pathogenic if it gains access to the human intestine. Which other species, if it coinhabited a human intestine along with species D, is most likely to result in a recombinant species that is both pathogenic and resistant to some antibiotics?

A) species A

B) species B

C) species C

D) species D

E) species E

C

19) Which species might be able to include Hfr cells?

A) species A

B) species B

C) species C

D) species D

E) species E

D

Which species is most self-sustaining in terms of obtaining nutrition in environments containing little fixed nitrogen or carbon?

A) species A

B) species B

C) species C

D) species D

E) species E

E

Which two species might be expected to cooperate metabolically, perhaps forming a biofilm wherein one species surrounds cells of the other species?

A) species A and B

B) species A and C

C) species B and E

D) species C and D

E) species C and E

A

Which species is most likely to be found both in sewage treatment plants and in the guts of cattle?

A) species A

B) species B

C) species C

D) species D

E) species E

B

Which species is probably an important contributor to the base of aquatic food chains as a primary producer?

A) species A

B) species B

C) species C

D) species D

E) species E

E

Consider the thermoacidophile Sulfolobus acidocaldarius. Which of the following graphs most accurately depicts the expected temperature and pH profiles of its enzymes? (Note: The horizontal axes of these graphs are double, with pH above and temperature below.)

A)

B)

C)

D)

A

If the complex protein assemblage of the prokaryotic flagellum arose by the same general processes as those of the complex eyes of molluscs (such as squids and octopi), then

A) natural selection cannot account for the rise of the prokaryotic flagellum.

B) ancestral versions of this protein assemblage were either less functional or had different functions than modern prokaryotic flagella.

C) scientists should accept the conclusion that neither eyes nor flagella could have arisen by evolution.

D) we can conclude that both of these structures must have arisen through the direct action of an "intelligent designer."

B

Certain proteins of the complex motor that drives bacterial flagella are modified versions of proteins that had previously belonged to plasma membrane pumps. This evidence supports the claim that

A) some structures are so complex that natural selection cannot, and will not, explain their origins.

B) the power of natural selection allows it to act in an almost predictive fashion, producing organs that will be needed in future environments.

C) the motors of bacterial flagella were originally synthesized abiotically.

D) natural selection can produce new structures by coupling together parts of other structures.

E) bacteria that possess flagella must have lost the ability to pump certain chemicals across their plasma membranes.

D

A hypothetical bacterium swims among human intestinal contents until it finds a suitable location on the intestinal lining. It adheres to the intestinal lining using a feature that also protects it from phagocytes, bacteriophages, and dehydration. Fecal matter from a human in whose intestine this bacterium lives can spread the bacterium, even after being mixed with water and boiled. The bacterium is not susceptible to the penicillin family of antibiotics. It contains no plasmids and relatively little peptidoglycan.

3) This bacterium's ability to survive in a human who is taking penicillin pills may be due to the presence of which of the following?

1. penicillin-resistance genes

2. a secretory system that removes penicillin from the cell

3. a gram-positive cell wall

4. a gram-negative cell wall

5. an endospore

A) 1 or 5

B) 2 or 3

C) 4 or 5

D) 2, 3, or 5

E) 2, 4, or 5

E

Adherence to the intestinal lining by this bacterium is due to its possession of

A) fimbriae.

B) pili.

C) a capsule.

D) a flagellum.

E) a cell wall with an outer lipopolysaccharide membrane.

C

What should be true of the cell wall of this bacterium?

A) Its innermost layer is composed of a phospholipid bilayer.

B) After it has been subjected to Gram staining, the cell should remain purple.

C) It has an outer membrane of lipopolysaccharide.

D) It is mostly composed of a complex, cross-linked polysaccharide.

E) Two of the responses above are correct.

C

Some of the proteins that allow this bacterium to swim are related (in an evolutionary sense) to proteins that

A) attach to the single chromosome.

B) act as restriction enzymes.

C) synthesize peptidoglycan for the cell wall.

D) move macromolecules out of the cell.

E) comprise its ribosomes.

D

In which feature(s) should one be able to locate a complete chromosome of this bacterium?

1. nucleolus

2. prophage

3. endospore

4. nucleoid

A) 4 only

B) 1 and 3

C) 2 and 3

D) 3 and 4

E) 2, 3, and 4

D

The cell also lacks F factors and F plasmids. Upon its death, this bacterium should be able to participate in

A) conjugation.

B) transduction.

C) transformation.

D) A and B

E) B and C

F) all of the choices are correct.

C

This bacterium derives nutrition by digesting human intestinal contents (in other words, food). Thus, this bacterium should be an

A) aerobic chemoheterotroph.

B) aerobic chemoautotroph.

C) anaerobic chemoheterotroph.

D) anaerobic chemoautotroph.

C

This bacterium derives nutrition by digesting human intestinal contents (in other words, food). Humans lacking this bacterium have no measurable reproductive advantage or disadvantage relative to humans who harbor this bacterium. Consequently, the bacterium can be properly described as which of the following?

1. symbiont

2. endosymbiont

3. mutualist

4. commensal

A) 4 only

B) 1 and 2

C) 1 and 4

D) 2 and 3

E) 2 and 4

C

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 O2produced by neighboring cells. Intracellular connections allow heterocysts to transport fixed nitrogen to neighboring cells in exchange for carbohydrates."

11) 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

Which two of the following questions arise from a careful reading of this quotation, and are most important for understanding how N2 enters heterocysts, and how O2 is kept out of heterocysts?

1. If carbohydrates can enter the heterocysts 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 heterocysts contain the genes that code for photosynthesis, how can these cells fail to perform photosynthesis?

5. If the cell walls of Anabaena's heterocysts are permeable to N2, how is it that N2 doesn't diffuse out of the heterocysts before it can be fixed?

6. If the thick cell walls of the heterocysts exclude entry of oxygen gas, how is it that they don't also exclude the entry of nitrogen gas?

A) 1 and 3

B) 1 and 6

C) 2 and 5

D) 3 and 4

E) 4 and 6

B

Which of the following steps has not yet been accomplished by scientists studying the origin of life?

A) synthesis of small RNA polymers by ribozymes

B) abiotic synthesis of polypeptides

C) formation of molecular aggregates with selectively permeable membranes

D) formation of protocells that use DNA to direct the polymerization of amino acids

E) abiotic synthesis of organic molecules

D

Fossilized stromatolites

A) more than 2.8 billion years old have not been discovered.

B) formed around deep-sea vents.

C) resemble structures formed by bacterial communities that are found today in some shallow marine bays.

D) provide evidence that plants moved onto land in the company of fungi around 500 million years ago.

E) contain the first undisputed fossils of eukaryotes and date from 1.8 billion years ago.

C

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 methane as a carbon source.

B) light as an energy source and CO2 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.

B

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

Bacteria perform the following ecological roles. Which role typically does not involve symbiosis?

A) skin commensalist

B) pathogen

C) bioluminescent bacteria in fish

D) gut mutualist

E) decomposer

E

Plantlike photosynthesis that releases O2 occurs in

A) cyanobacteria.

B) chlamydias.

C) archaea.

D) actinomycetes.

E) chemoautotrophic bacteria.

A