Why is salt a good preservative to use for foods such as pork and fish?
Prokaryotic cells living in the food will shrink from their cell walls, impacting their ability to reproduce.
Gram-negative bacteria have ________ peptidoglycan than gram-positive cells, and their cell walls are __________ complex structurally.
Less...More
A gram-negative cell wall consists of _____________.
a thin layer of peptidoglycan surrounded by an outer membrane containing lipopolysaccharides.
Bacteria that ________ tend to have abundant internal membranes.
are photosynthetic
Bacterial cells, but not eukaryotic cells, possess ______________.
a nucleoid with a circular chromosome
Bacterial flagella have a very complex structure composed of 42 distinct proteins. What s the most likely explanation for the evolution of these complex structures?
exaptation
The bacteria that cause tetanus can be killed only by prolonged heating at temperatures considerably above boiling. This suggests that these bacteria _______________.
produce endospores
Plasmids ___________.
-Replicate independently of the main chromosome
-Allow bacteria to survive adverse conditions
-Often contain antibiotic resistance genes
-Are transferred from on bacterium to another by conjugation.
(All the listed responses are correct)
How is it possible that as many as 9 million mutations can arise each day in the E. coli inhabiting one human?
The mathematics of large population size and rapid reproduction rate combine to produce many mutations without a particularly high mutation rate.
In the absence of meiosis and sexual reproduction, what general process allows genetic recombination among prokaryotes?
Horizontal gene transer
Which statement about transformation is true?
It can be facilitated by cell-surface proteins that recognize compatible DNA.
An F+ bacterial cell _____________.
acts as a donor during conjugation
Which of the following is true about R plasmids?
-They can be transferred from one bacterium to another via conjugation.
-They can carry several resistance genes.
(Both the second and third answers are correct)
Bacteria that use light for their energy source and CO2 for their carbon source are called ________________.
Photo-autotrophs
In an experiment, a microbiologist put equal numbers of each of the following organisms into a flask of sterile north, consisting mostly of sugar and a few amino acids. She the placed the flask in the dark. Which of the organisms would be most likely to survive?
Chemo-heterotrophic bacteria
The Desulfovibrio bacterium breaks down organic matter (which it must have) and uses sulfate (not oxygen) as an electron acceptor. As a result, it produces hydrogen sulfide (H2S), accounting for the "rotten egg" smell of swamp muck. Oxygen is a deadly poison to Desulfovibrio. We would call Desullfovibrio a(n) _________.
Obligately anaerobic chemoautotroph
Choose the list below that contains the substances required by typical nitrogen-fixing cyanobacteria.
carbon dioxide, nitrogen, water, light, and some minerals
What is the role of heterocysts in a cyanobacterial filament?
They carry out only nitrogen fixation.
Biofilms are an example of ____________.
metabolic cooperation among prokaryotic species
Portions of the genomes of certain prokaryotic species are very similar to portions of the genomes of distantly related prokaryotes. The process that most likely accounts for this genetic similarity is _______________.
horizontal gene transfer
Which subgroup of proteobacteria contains many species that are closely associated with eukaryotic hosts in mutualistic or parasitic relationships?
alpha
Which subgroup of proteobacteria contains many species that are predators of other bacteria?
delta
Which group of bacteria is unusual in that they lack peptidoglycan in their cell walls?
chlamydias
Which of the following is a difference between bacteria and archaea?
They have different chemicals in their cell membranes and cell walls.
Which of the following statement about cyanobacteria is true?
-Some are single cells, whereas other live in filamentous colonies.
-They are the only prokaryotes that perform plantlike, oxygenic photosynthesis.
-It can be said that nitrogen-fixing cyanobacteria are the most self-sufficient of all organisms.
-Some species may carry on nitrogen fixation.
(All of the listed responses are correct)
Prokaryotes found inhabiting the Great Salt Lake would be ____________.
extreme halophiles
Which of the flowing groups of prokaryotes is classified as a member of the domain Archaea?
methanogens
Which clade of archaea includes most of the extreme thermophiles?
Crenarchaeota
Prokaryotes are completely indispensable to which chemical cycle?
nitrogen
A type of ecological relationship called _______ involves one organism living at the expense of another organism.
parasitism
Which example below is a correct statement about Bacteroides thetaoitaomicron, a bacterium that lives in the human intestines?
The bacteria have a mutualistic relationship with the human body.
Ticks that live on deer and field mice are responsible for spreading the bacterium ________, which causes ___________.
Borrelia burgdorferi....Lyme disease
Which statement is true regarding cholera?
Its symptoms are caused by an exotoxin that stimulates intestinal cells to release chloride ions into the gut.
Scientists hypothesize that the O157:H7 strain of E. coli is to different from the K-12 strain because of ___________.
horizontal gene transfer over many years, most likely through the action of bacteriophages
Which statement about prokaryotes is true?
Prokaryotes are widely used for bioremediation.