Question 1

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

Accepted Answer

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

Question 2

Use the information in the following paragraph to answer the next few questions.
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.
-This bacterium's ability to survive in a human who is taking penicillin pills may be due to the presence of
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.

Accepted Answer

A) 1 or 5 
B) 2 or 3 
C) 4 or 5 
D) 2, 3, or 5 
E) 2, 4, or 5

Question 3

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

Accepted Answer

A) 2 only 
B) 4 only 
C) 2 and 5 
D) 1, 3, and 5 
E) 1, 4, and 5

Question 4

Hershey and Chase performed an elegant experiment that convinced most biologists that DNA,rather than protein,was the genetic material.This experiment subjected bacteria to the same gene transfer mechanism as occurs in

Accepted Answer

A) transduction. 
B) transformation. 
C) conjugation. 
D) binary fission. 
E) endosymbiosis.

Question 5

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?

Accepted Answer

A) via sex pili 
B) via transduction 
C) via conjugation 
D) via transformation 
E) Two of the responses above are correct.

Question 6

The following questions refer to the information and figure below.
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.
 
-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?

Accepted Answer

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

Question 7

Which statement about the genomes of prokaryotes is correct?

Accepted Answer

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.

Question 8

In general,what is the primary ecological role of prokaryotes?

Accepted Answer

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

Question 9

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?

Accepted Answer

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.

Question 10

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

Accepted Answer

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 able to use a much greater variety of molecules as food sources than can eukaryotes.

Question 11

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

Accepted Answer

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

Question 12

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

Accepted Answer

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.

Question 13

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

Accepted Answer

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

Question 14

The figure below 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 this figure to answer the following questions.
 
-How is the recipient cell different at Time D than it was at Time A?

Accepted Answer

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.

Question 15

For several decades now,amphibian species worldwide have been in decline.A significant proportion of the decline seems to be due to the spread of the chytrid fungus,Batrachochytrium dendrobatidis (Bd).Chytrid sporangia reside within the epidermal cells of infected animals,animals that consequently show areas of sloughed skin.They can also be lethargic,which is expressed through failure to hide and failure to flee.The infection cycle typically takes four to five days,at the end of which zoospores are released from sporangia into the environment.In some amphibian species,mortality rates approach 100%; other species seem able to survive the infection.
-If infection primarily involves the outermost layers of adult amphibian skin,and if the chytrids use the skin as their sole source of nutrition,then which term best applies to the chytrids?

Accepted Answer

A) anaerobic chemoautotroph 
B) aerobic chemoautotroph 
C) anaerobic chemoheterotroph 
D) aerobic chemoheterotroph

Question 16

Match the numbered terms to the description that follows.Choose all appropriate terms.
1)autotroph
2)heterotroph
3)phototroph
4)chemotroph
Description: an organism that relies on photons to excite electrons within its membranes

Accepted Answer

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

Question 17

Regarding prokaryotic genetics,which statement is correct?

Accepted Answer

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.

Question 18

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

Accepted Answer

A) attach to the single chromosome. 
B) act as restriction enzymes. 
C) synthesize peptidoglycan for the cell wall. 
D) move penicillin out of the cell. 
E) comprise its ribosomes.

Question 19

Mycoplasmas are bacteria that lack cell walls.On the basis of this structural feature,which statement concerning mycoplasmas should be true?

Accepted Answer

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.

Question 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

Accepted Answer

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.

Exam 27: Bacteria and Archaea