Chapter 27 Test (1-10) Flashcards
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) are obligate anaerobes.
B) are unable to swim through these thick and viscous materials.
C) experience lysis.
D) are unable to metabolize the glucose or fructose, and thus starve to death.
E) undergo death by plasmolysis.
E) undergo death by plasmolysis.
If all prokaryotes on Earth suddenly vanished, which of the following would be the most likely and most direct result?
A) There would be no more pathogens on Earth.
B) The number of organisms on Earth would decrease by 1020%.
C) The recycling of nutrients would be greatly reduced, at least initially.
D) Bacteriophage numbers would dramatically increase.
E) Human populations would thrive in the absence of disease.
C) The recycling of nutrients would be greatly reduced, at least initially.
Which of the following statements is not true?
A) Both archaea and bacteria generally lack membrane-enclosed organelles.
B) Archaea and bacteria have different membrane lipids.
C) The cell walls of archaea lack peptidoglycan.
D) Only bacteria have histones associated with DNA.
E) Only some archaea use CO 2 to oxidize H2, releasing methane
D) Only bacteria have histones associated with DNA.
Genetic variation in bacterial populations cannot result from
A) mutation.
B) transformation
C) conjugation
D) transduction.
E) meiosis.
E) meiosis.
Which statement about the relationship between bacteria and the human body is most accurate?
A) Bacteria are found in the mouth, stomach, and intestines in about equal amounts.
B) Although many tissues are kept bacteria-free, around 100 trillion bacteria live on or in us.
C) About one -tenth of our body weights are due to bacteria
D) Most bacteria are transient; that is, they come for brief periods and then are gone.
B) Although many tissues are kept bacteria-free, around 100 trillion bacteria live on or in us.
Disease-causing bacteria are called:
A) archaea.
B) pathogens.
C) cyanobacteria.
D) viroids.
E) protozoa.
B) pathogens.
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 have cell walls only for protection from herbivores.
B) Their cell walls are composed of very different biochemicals.
C) Some have cell walls only for support.
D) Some closely resemble animals, which lack cell walls.
E) Some have cell walls only to control osmotic balance.
B) Their cell walls are composed of very different biochemicals.
The causative agents of bubonic plague, which killed 100 million people during the 14th century, were:
A) fish.
B) rats.
C) viruses.
D) fleas.
E) bacteria.
E) bacteria.
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) Cell walls prevent cells from dying in hypertonic conditions.
Microbiologists use the Gram stain to aid in the identification of bacteria. What is the major difference between Gram-positive and Gram-negative bacteria?
A) structure of the lipids in the plasma membrane
B) presence or absence of muramic acid in the cell wall
C) presence or absence of outer plasma membrane
D) presence or absence of peptidoglycan in the cell wall
C) presence or absence of outer plasma membrane
