Question 1

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

Accepted Answer

A) 3.5 million years 
B) 5.0 million years 
C) 3.5 billion years 
D) 5.0 billion years 
A) 3.5 million years 
B) 5.0 million years 
C) 3.5 billion years 
D) 5.0 billion years

Question 2

Please use the following information to answer the question(s)below.
In Figure 24.1,data are presented from an eight-year experiment in which 12 populations of Escherichia 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
-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?

Accepted Answer

A) number of offspring or close kin that survive to reproductive age 
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 
A) number of offspring or close kin that survive to reproductive age 
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

Question 3

Photoautotrophs use

Accepted Answer

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) H2S as an energy source and CO2 as a carbon source. 
D) CO2 as both an energy source and a carbon source. 
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) H2S as an energy source and CO2 as a carbon source. 
D) CO2 as both an energy source and a carbon source.

Question 4

What is the best explanation for how a motor unit of a flagellum can stay in its correct location within a bacterial cell wall and membrane?

Accepted Answer

A) It is attached to the membrane using proteinaceous fibers. 
B) Some portions of the proteins of the motor unit have regions of polar hydrophilic amino acids,and others have non-polar hydrophobic amino acids. 
C) The force of the flagellum filament keeps the motor unit pinned to the membrane. 
D) The rod portion of the motor unit forms a tube-like structure that uses the suction of water to keep it in place. 
A) It is attached to the membrane using proteinaceous fibers. 
B) Some portions of the proteins of the motor unit have regions of polar hydrophilic amino acids,and others have non-polar hydrophobic amino acids. 
C) The force of the flagellum filament keeps the motor unit pinned to the membrane. 
D) The rod portion of the motor unit forms a tube-like structure that uses the suction of water to keep it in place.

Question 5

Scientists have identified two major branches of prokaryotic evolution.What was the basis for dividing prokaryotes into two domains?

Accepted Answer

A) microscopically observed 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 
A) microscopically observed 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

Question 6

What is a main difference between endotoxins and exotoxins?

Accepted Answer

A) Endotoxins are proteins,and exotoxins are lipopolysaccharides. 
B) Endotoxins are lipopolysaccharides and thus structurally integral to the bacterium,whereas exotoxins are proteins that are secreted by living bacteria. 
C) Exotoxins are released only when the bacteria die and their cell walls break down. 
D) Exotoxins are made of RNA,and endotoxins are made of DNA. 
A) Endotoxins are proteins,and exotoxins are lipopolysaccharides. 
B) Endotoxins are lipopolysaccharides and thus structurally integral to the bacterium,whereas exotoxins are proteins that are secreted by living bacteria. 
C) Exotoxins are released only when the bacteria die and their cell walls break down. 
D) Exotoxins are made of RNA,and endotoxins are made of DNA.

Question 7

Which of the following processes is least associated with the others?

Accepted Answer

A) horizontal gene transfer 
B) genetic recombination 
C) conjugation 
D) transformation 
E) binary fission 
A) horizontal gene transfer 
B) genetic recombination 
C) conjugation 
D) transformation 
E) binary fission

Question 8

The table depicts characteristics of five prokaryotic species (A-E).Use the information in the table to answer the following question(s).
   Table 24.1
-In Table 24.1,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?

Accepted Answer

A) species A 
B) species B 
C) species C 
D) species D 
E) species E 
A) species A 
B) species B 
C) species C 
D) species D 
E) species E

Question 9

Which of the following statements is true?

Accepted Answer

A) Archaea and bacteria have the same type of membrane lipids. 
B) The cell walls of archaea have peptidoglycan. 
C) Only bacteria have histones associated with DNA. 
D) Only some archaea use CO2 to oxidize H2,releasing methane. 
A) Archaea and bacteria have the same type of membrane lipids. 
B) The cell walls of archaea have peptidoglycan. 
C) Only bacteria have histones associated with DNA. 
D) Only some archaea use CO2 to oxidize H2,releasing methane.

Question 10

Which pair of proteobacterial subgroups shown in the figure are most closely related through evolution?

Accepted Answer

A) alpha and beta 
B) beta and gamma 
C) gamma and delta 
D) epsilon and beta 
A) alpha and beta 
B) beta and gamma 
C) gamma and delta 
D) epsilon and beta

Question 11

Which of the following describes an organism that obtains energy from light?

Accepted Answer

A) autotroph only 
B) phototroph only 
C) autotroph and phototroph 
D) heterotroph and chemotroph 
E) autotroph,phototroph,and chemotroph 
A) autotroph only 
B) phototroph only 
C) autotroph and phototroph 
D) heterotroph and chemotroph 
E) autotroph,phototroph,and chemotroph

Question 12

Figure 24.2 depicts changes to the amount of DNA present in a recipient cell that is engaged in conjugation with an Hfr cell.Hfr cell DNA begins entering the recipient cell at time A.Assume that reciprocal crossing over occurs (in other words,a fragment of the recipient's chromosome is exchanged for a homologous fragment from the Hfr cell's DNA).Use Figure 24.2 to answer the following question(s).
   Figure 24.2
-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?

Accepted Answer

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) 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?

Question 13

Two prokaryotes are shown in the figure that have additional cellular membranes within the plasma membrane.What functions could the respiratory membranes and the thylakoid membranes provide?

Accepted Answer

A) These are both autotrophic evolutionary adaptations to allow organic molecule production. 
B) The respiratory membrane allows a functional electron transport chain and oxidative phosphorylation of ATP. 
C) The thylakoid membrane allows the fixation of CO2 during the Calvin Cycle. 
D) The respiratory membrane provides a location to conduct the citric acid cycle. 
A) These are both autotrophic evolutionary adaptations to allow organic molecule production. 
B) The respiratory membrane allows a functional electron transport chain and oxidative phosphorylation of ATP. 
C) The thylakoid membrane allows the fixation of CO2 during the Calvin Cycle. 
D) The respiratory membrane provides a location to conduct the citric acid cycle.

Question 14

Several scientific laboratories across the globe are performing research concerning the origin of life on Earth.Suppose one of these laboratories conducts abiotic experiment(s)to test the potential for hydrogen bonding between various nucleic acids and amino acids.Which of the following results of such experiments are most consistent with our current understanding of Earth's first genetic systems?

Accepted Answer

A) 
  
B) 
  
C) 
  
D) 
  
A) 
  
B) 
  
C) 
  
D)

Question 15

What is one key difference between genetic transformation and transduction in prokaryotes?

Accepted Answer

A) Transduction involves the uptake of foreign DNA from the surroundings,whereas transformation involves a virus transferring DNA from one bacterium to another. 
B) Transformation involves the uptake of foreign DNA from the surroundings,whereas transduction involves a virus transferring DNA from one bacterium to another. 
C) Transformation involves eukaryotes as the source of DNA,whereas transduction involves a transfer of DNA between bacteria. 
D) Transduction is the physical joining of one bacterium to another,whereas transformation is the uptake of DNA via a viral source. 
A) Transduction involves the uptake of foreign DNA from the surroundings,whereas transformation involves a virus transferring DNA from one bacterium to another. 
B) Transformation involves the uptake of foreign DNA from the surroundings,whereas transduction involves a virus transferring DNA from one bacterium to another. 
C) Transformation involves eukaryotes as the source of DNA,whereas transduction involves a transfer of DNA between bacteria. 
D) Transduction is the physical joining of one bacterium to another,whereas transformation is the uptake of DNA via a viral source.

Question 16

On early Earth,more than 4 billion years ago,environmental conditions were very different from those today because

Accepted Answer

A) only early Earth was intensely bombarded by large rocks and ice from space. 
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) only early Earth was intensely bombarded by large rocks and ice from space. 
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.

Question 17

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 means by which beneficial mutations might be transmitted horizontally to other E.coli cells?

Accepted Answer

A) via sex pili 
B) via transduction 
C) via conjugation 
D) via transformation 
A) via sex pili 
B) via transduction 
C) via conjugation 
D) via transformation

Question 18

The majority of a bacterium's key genetic information is located in the

Accepted Answer

A) flagella. 
B) nucleoid. 
C) capsule. 
D) plasmids. 
E) endospore. 
A) flagella. 
B) nucleoid. 
C) capsule. 
D) plasmids. 
E) endospore.

Question 19

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?

Accepted Answer

A) transduction 
B) conjugation 
C) translation 
D) binary fission 
E) horizontal gene transfer 
A) transduction 
B) conjugation 
C) translation 
D) binary fission 
E) horizontal gene transfer

Question 20

Please use the following information to answer the question below.
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 heterocysts to transport fixed nitrogen to neighboring cells in exchange for carbohydrates."
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?

Accepted Answer

A) package them in membranes that are impermeable to all gases,and package these enzymes in specialized cells or compartments that inhibit oxygen entry 
B) be obligate anaerobes and package these enzymes in specialized cells or compartments that inhibit oxygen entry 
C) be obligate anaerobes and be facultative aerobes 
D) be facultative aerobes and package these enzymes in specialized cells or compartments that inhibit oxygen entry 
A) package them in membranes that are impermeable to all gases,and package these enzymes in specialized cells or compartments that inhibit oxygen entry 
B) be obligate anaerobes and package these enzymes in specialized cells or compartments that inhibit oxygen entry 
C) be obligate anaerobes and be facultative aerobes 
D) be facultative aerobes and package these enzymes in specialized cells or compartments that inhibit oxygen entry

Exam 24: Early Life and the Diversification of Prokaryotes

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

Photoautotrophs use

What is the best explanation for how a motor unit of a flagellum can stay in its correct location within a bacterial cell wall and membrane?

Scientists have identified two major branches of prokaryotic evolution.What was the basis for dividing prokaryotes into two domains?

What is a main difference between endotoxins and exotoxins?

Which of the following processes is least associated with the others?

Which of the following statements is true?

Which pair of proteobacterial subgroups shown in the figure are most closely related through evolution?

Which of the following describes an organism that obtains energy from light?

Two prokaryotes are shown in the figure that have additional cellular membranes within the plasma membrane.What functions could the respiratory membranes and the thylakoid membranes provide?

What is one key difference between genetic transformation and transduction in prokaryotes?

On early Earth,more than 4 billion years ago,environmental conditions were very different from those today because

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 means by which beneficial mutations might be transmitted horizontally to other E.coli cells?

The majority of a bacterium's key genetic information is located in the

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?

Introduction: Evolution and the Foundations of Biology

The Chemical Context of Life

Carbon and the Molecular Diversity of Life

A Tour of the Cell

Membrane Transport and Cell Signaling

An Introduction to Metabolism

Cellular Respiration and Fermentation

Photosynthesis

The Cell Cycle

Meiosis and Sexual Life Cycles

Mendel and the Gene Idea

The Chromosomal Basis of Inheritance

The Molecular Basis of Inheritance

Gene Expression: From Gene to Protein

Regulation of Gene Expression

Development,stem Cells,and Cancer

Viruses

Genomes and Their Evolution

Descent With Modification

Phylogeny

The Evolution of Populations

The Origin of Species

Broad Patterns of Evolution

The Origin and Diversification of Eukaryotes

The Colonization of Land by Plants and Fungi

The Rise of Animal Diversity

Plant Structure and Growth

Resource Acquisition,nutrition,and Transport in Vascular Plants

Reproduction and Domestication of Flowering Plants

Plant Responses to Internal and External Signals

Homeostasis and Endocrine Signaling

Animal Nutrition

Circulation and Gas Exchange

The Immune System

Reproduction and Development

Neurons,synapses,and Signaling

Nervous and Sensory Systems

Motor Mechanisms and Behavior

Population Ecology and the Distribution of Organisms

Ecological Communities

Ecosystems and Energy

Conservation Biology and Global Change

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