Title: Prokaryotes
Course: Question Banks

Q: The earliest forms of life on Earth were ________.
- individual phototrophs (Incorrect. The earliest forms of life were not phototrophs; these appeared about 1 billion years after the formation of Earth.)
- aerobic cyanobacteria (Incorrect. Cyanobacteria appeared about 1 billion years after phototrophs.)
- microbial mats (Correct. The earliest forms of life were most likely microbial mats, a multi-layered sheet of prokaryotes.)
A: microbial mats

Q: Prehistoric microbial mats obtained their energy from ________.
- solar radiation (Incorrect. On early Earth, solar radiation was not reduced by an ozone layer so it would actually have damaged any biological organisms exposed directly to its rays.)
- eating each other (Incorrect. Producers had to appear in the tree of life before consumers did.)
- hydrothermal vents (Correct. The first microbial mats likely obtained chemical energy from the expulsions from hydrothermal vents on the ocean floor.)
A: hydrothermal vents

Q: The earliest records of life on Earth are ________.
- stalactites (Incorrect. These are crystallized calcium deposits from the roofs of caves.)
- fossilized cells (Incorrect. Early cells would have had no “hard parts” to fossilize.)
- stromatolites (Correct. These structures are formed from minerals precipitated out of water by prokaryotes.)
A: stromatolites

Q: ________ are able to grow and thrive under conditions that would kill most other organisms.
- Prokaryotes (Incorrect. Many prokaryotes require the same living conditions as other organisms like plants and animals.)
- Superbugs (Incorrect. Superbugs is a term applied to bacteria that are resistant to the antibiotics generally used to kill that type of bacteria.)
- Extremophiles (Correct. Extremophiles thrive under conditions that would generally kill other life forms, such as high heat, high salt, or extremes of pH.)
A: Extremophiles

Q: ________ live and thrive in extremely low temperatures.
- Hypothermophiles (Incorrect. There are no “hypothermophiles.”)
- Thermophiles (Incorrect. Thermophiles live at high temperatures, between 60–80oC.)
- Psychrophiles (Correct. Psychrophiles live at temperatures of −15–10 oC.)
A: Psychrophiles

Q: Organisms such as ________ are adapted to survive extreme environments but do not prefer this type of environment.
- extremophilic prokaryotes (Incorrect. Most extremophiles actually prefer, or require, the extreme environments in which they live.)
- osmophiles (Incorrect. Osmophiles require high sugar concentrations for optimal growth.)
- radioresistant prokaryotes (Correct. Some extremophiles, like radioresistant ones, have developed mechanisms to cope with extreme environments but do not prefer these environments.)
A: radioresistant prokaryotes

Q: The nucleoid is ________.
- the site of protein synthesis in prokaryotes (Incorrect. Proteins are synthesized throughout the cytoplasm of prokaryotes.)
- a newly formed bacterial cell (Incorrect. The nucleoid is not a cell of any type.)
- an accumulation of prokaryotic DNA (Correct. The nucleoid can be thought of as analogous to the eukaryotic nucleus, though it is not protected in a separate membrane.)
A: an accumulation of prokaryotic DNA

Q: ________ in prokaryotes enables the direct exchange of genetic information between two cells.
- Transduction (Incorrect. While transduction does introduce new genetic material into a prokaryotic cell, it occurs through a viral carrier.)
- Transformation (Incorrect. Transformation involves a cell absorbing DNA found in its environment.)
- Conjugation (Correct. During conjugation, a sex pilus transfers DNA from one cell to another.)
A: Conjugation

Q: In binary fission ________.
- one cell splits in half, halving its DNA as well (Incorrect. This is the process of meiosis in forming gametes.)
- a growth appears on a cell, and the growth is severed off to become a new organism (Incorrect. This sort of, but not quite, describes budding.)
- one cell duplicates its DNA and then pinches in half (Correct. Most prokaryotes reproduce by binary fission in which one cell duplicates its DNA and then pinches in half.)
A: one cell duplicates its DNA and then pinches in half

Q: The cell walls of ________ are composed mainly of peptidoglycan.
- archaea (Incorrect. Archaean cell walls do not contain peptidoglycan; there are actually four different types of cell walls in archaea.)
- fungi (Incorrect. Fungal cell walls contain chitin.)
- bacteria (Correct. Bacterial cell walls are based on peptidoglycan.)
A: bacteria

Q: The ________ in Archaea is different from that of all other domains of life.
- genetic material (Incorrect. Archaea use DNA as their genetic material, as do Bacteria and Eukarya.)
- ribosomes (Incorrect. The basic structure and function of ribosomes is the same in all organisms; that is why they can be used to study the tree of life.)
- cell membrane (Correct. Archaean cell membranes are based on a phospholipid bilayer with phytanyl side chains instead of fatty acids tails. Additionally, the lipid is attached to the glycerol head with an ether bond instead of an ester bond.)
A: cell membrane

Q: ________ are divided into two major groups based on cell wall structure.
- Archaea (Incorrect. There are not two major groups in Archaea.)
- Prokarya (Incorrect. The two major divisions in Prokarya are not based on cell wall structure.)
- Bacteria (Correct. Scientists use Gram staining to distinguish bacteria into either Gram positive or Gram negative groups; the difference in staining results is based on cell wall structure.)
A: Bacteria

Q: A species definition that involves interbreeding applies ________.
- only to prokaryotes (Incorrect. A large number of prokaryotes reproduce asexually, so they never interbreed.)
- to both prokaryotes and eukaryotes (Incorrect. A large number of prokaryotes reproduce asexually, so they never interbreed.)
- only to eukaryotes (Correct. Eukaryotic organisms generally reproduce through sexual reproduction, so a definition that involves interbreeding works for this domain.)
A: only to eukaryotes

Q: Prokaryotes can be classified into species based on ________.
- habitat (Incorrect. Habitat is not a factor typically used to classify prokaryotes into species.)
- reproductive strategy (Incorrect. Most prokaryotes reproduce asexually, so this is not used to classify them as species.)
- genetic sequences (Correct. Modern species classifications for prokaryotic organisms are often based on shared genes.)
A: genetic sequences

Q: The ________ is the collective genome of a prokaryotic community.
- combogenome (Incorrect. There is no combogenome.)
- hypergenome (Incorrect. There is no hypergenome.)
- metagenome (Correct. The metagenome is the genome of an entire prokaryotic community.)
A: metagenome

Q: The macronutrient ________ is required for the synthesis of nucleotides and phospholipids.
- nitrogen (Incorrect. Nitrogen is required for proteins, nucleic acids, and some other cell constituents.)
- oxygen (Incorrect. Oxygen is component of many organic compounds and water, but is not the best answer choice.)
- phosphorus (Correct. All organisms require phosphorus to make nucleotides and phospholipids.)
A: phosphorus

Q: ________ is a micronutrient used as an enzyme cofactor by some prokaryotes.
- Iron (Incorrect. Iron is a trace element but is used in electron-transport reactions.)
- Sulfur (Incorrect. Sulfur is actually considered a macronutrient for prokaryotes.)
- Boron (Correct. Boron, chromium, and manganese are all micronutrients used primarily as enzyme cofactors by some prokaryotic organisms.)
A: Boron

Q: Which of the following statements is true about nitrogen?
- It accounts for 50 percent of the composition of a cell. (Incorrect. Nitrogen is not 50 percent of a cell’s composition.)
- It is important for some amino acids and several vitamins and coenzymes. (Incorrect. This does not best describe nitrogen.)
- It presents 12 percent of the dry weight of cells and is a major component of proteins and nucleic acids. (Correct. Nitrogen is present in proteins, nucleic acids, and other cell constituents.)
A: It presents 12 percent of the dry weight of cells and is a major component of proteins and nucleic acids.

Q: Photoautotrophs obtain their energy from ________ and their carbon from ________.
- hydrothermal vents; carbon dioxide (Incorrect. This would be a chemoautotroph; these are found near hydrothermal vents on the deep ocean floor where sunlight does not penetrate.)
- sunlight; carbohydrates (Incorrect. This would be a photoheterotroph. There are a few of these organisms around; they need an organic carbon source to satisfy their carbon requirements because carbon dioxide alone is insufficient.)
- sunlight; carbon dioxide (Correct. The photo indicates sunlight and the auto indicates these organisms can fix inorganic carbon (carbon dioxide) into organic molecules.)
A: sunlight; carbon dioxide

Q: The process of ________ captures inorganic carbon in the form of organic compounds.
- carbon conversion (Incorrect. This is not the term used to describe this process.)
- organic fixation (Incorrect. This is not the term used to describe this process.)
- carbon fixation (Correct. Inorganic carbon from carbon dioxide is “fixed” into organic compounds by autotrophs.)
A: carbon fixation

Q: Which metabolic strategy would be common in extremophiles?
- chemoheterotrophy (Incorrect. Many extreme environments do not support a lot of biological life, so it would be harder to find an organic source of carbon (another organism to eat).)
- photoheterotrophy (Incorrect. Many extreme environments do not support a lot of biological life, so it would be harder to find an organic source of carbon (another organism to eat).)
- chemoautotrophy (Correct. Extremophiles could, and do, survive in extreme environments such as deep sea vents, where alternative energy and carbon sources are present.)
A: chemoautotrophy

Q: The most important biological contribution of carbon dioxide to the atmosphere is through ________.
- respiration from the lungs (Incorrect. This is not the most important biological contributor of atmospheric carbon dioxide.)
- burning organic material (Incorrect. While human energy consumption, including burning organic matter and combustion of fossil fuels, is a significant contributor of excess carbon dioxide to the atmosphere, this is not considered a natural biological contribution.)
- microbial decomposition of dead material (Correct. Prokaryotic organisms break down dead material from organisms that undergo cellular respiration.)
A: microbial decomposition of dead material

Q: In anoxic sediments in aqueous environments, prokaryotes produce ________ as part of a separate carbon cycle that eventually connects with the main, atmospheric-based, carbon cycle.
- carbonate (Incorrect. While carbonate is important in aqueous cycles (it is used to form shells for some organisms, this is not the correct answer.)
- carbon dioxide (Incorrect. While carbon dioxide is present in aqueous environments and does return to the atmosphere, this is not what prokaryotes produce in anoxic environments.)
- methane (Correct. Prokaryotes in anoxic sediments produce methane, which eventually moves through the aqueous environment until it finally converted and returned to the atmosphere in the form of carbon dioxide.)
A: methane

Q: The large reservoir of available ________ in terrestrial ecosystems is found in land plants.
- oxygen (Incorrect. There is not a specific reservoir of oxygen in terrestrial ecosystems; it is usually taken straight from the atmosphere.)
- nitrogen (Incorrect. Available nitrogen is concentrated in the nodules of legumes.)
- carbon (Correct. In terrestrial systems, the largest amount of available carbon is found in plants.)
A: carbon

Q: Much of the recycling of ________ from organic compounds in carried out by prokaryotes.
- carbon (Incorrect. Carbon is recycled by detritivores.)
- oxygen (Incorrect. Oxygen is readily recycled by everything during cellular respiration and photosynthesis.)
- nitrogen (Correct. Prokaryotes are responsible for most nitrogen recycling in the environment, in particular for fixing gaseous nitrogen into ammonia which can be used for plants.)
A: nitrogen

Q: Ammonification is the process of ________.
- conversion of ammonia to nitrite and nitrate (Incorrect. This is nitrification.)
- reduction of nitrate from soils to gaseous nitrogen compounds (Incorrect. This is denitrification.)
- releasing ammonia during decomposition of nitrogen-containing organic compounds (Correct. This is the release of ammonia during decomposition of organic compounds.)
A: releasing ammonia during decomposition of nitrogen-containing organic compounds

Q: ________ is necessary before plants can assimilate nitrogen compounds via their roots.
- Ammonification (incorrect. This process must occur first to add nitrogen to soils but something else must happen before plants can assimilate the nitrogen.)
- Denitrification (Incorrect. This is the reduction of nitrate from soils to gaseous nitrogen compounds that will enter the atmosphere.)
- Nitrification (Correct. This is the conversion of ammonia to nitrite and nitrate, which is what plants can directly assimilate using their root systems.)
A: Nitrification

Q: The Plague of Athens, which weakened Athens’ dominance and world power, was likely an epidemic of ________.
- bubonic plague (Incorrect. The Plague of Athens was not the bubonic plague.)
- a zoonotic disease (Incorrect. The Plague of Athens is not thought to have been a zoonotic disease.)
- typhoid fever (Correct. Recent studies indicate the Plague of Athens was likely an outbreak of typhoid fever.)
A: typhoid fever

Q: The Black Death was caused by an outbreak of ________.
- a zoonotic disease (Incorrect. This pandemic was not caused by a zoonotic disease though it is transmitted via animals and pests.)
- typhoid fever (Incorrect. This pandemic was not caused by typhoid fever.)
- bubonic plague (Correct. The Black Death was one of the most devastating pandemics caused by the bubonic plague.)
A: bubonic plague

Q: The majority of ________ caused by zoonotic diseases.
- ancient plagues were (Incorrect. Most ancient plagues were not zoonotic diseases.)
- recent epidemics are (Incorrect. There have been few recent epidemics, but so far they were not zoonotic diseases.)
- recently emerging infectious diseases are (Correct. Nearly 75 percent of emerging infectious diseases are zoonotic diseases appearing in humans for the first time.)
A: recently emerging infectious diseases are

Q: Antibiotic resistance appears to be growing in bacteria due to ________.
- antibiotics causing DNA mutations that lead to resistance (Incorrect. Antibiotics do not cause DNA mutations.)
- zoonotic combinations of resistance genes (Incorrect. To date no data indicates bacteria are sharing resistance genes across animal hosts but antibiotics are used heavily in the livestock industry.)
- overuse of antibiotics acting as a selective pressure for resistance adaptations (Correct. Antibiotics kill most of the target bacteria but naturally occurring mutations that make a bacterium resistance will protect it. Once the “weak” are wiped out, the resistant bacteria can proliferate with ample resources.)
A: overuse of antibiotics acting as a selective pressure for resistance adaptations

Q: An increasingly dangerous strain of antibiotic-resistant bacteria is ________.
- E. coli O157:H7 (Incorrect. This is the causative agent in a number of foodborne illness cases but is not antibiotic resistant.)
- H1N1 (Incorrect. H1N1 is actually a strain of the flu, which is a virus. Therefore antibiotics never worked on it.)
- methicillin-resistant Staphylococcus aureus (Correct. MRSA is resistant to a host of antibiotics, not just methicillin, and is becoming prevalent among older and younger populations who live in close quarters.)
A: methicillin-resistant Staphylococcus aureus

Q: Bacteria can exchange genes ________, spreading antibiotic resistance
- with viruses (Incorrect. Bacteria do not exchange genes with viruses.)
- within biofilms (Incorrect. Bacteria cannot exchange genes broadly within biofilms, as there are non-bacterial components to the film.)
- among different species (Correct. Once a single species develops a resistance, that gene may easily spread to other bacterial species, decreasing antibiotic effectiveness globally.)
A: among different species

Q: The oldest example of using prokaryotes to make food was likely to make ________.
- bread (Incorrect. While bread has “been around” for many years, it is not the oldest use of prokaryotes for food production.)
- cheese (Incorrect. Cheese likely dates from about 4,000 years ago, which is not the oldest use of prokaryotes for food production.)
- beer (Correct. Evidence exists that the Sumerians made beer about 6,000 years ago, which requires yeast and prokaryotic microbes.)
A: beer

Q: Prokaryotes are used to ________ in the case of processing milk.
- prevent spoilage (Incorrect. While processing milk into cheese will make it last longer, this will not totally prevent spoilage.)
- facilitate product transport (Incorrect. Milk is not processed into other products to make transportation easier.)
- preserve nutrients (Correct. Processing milk into cheese will preserve the nutrients in the milk, though not indefinitely.)
A: preserve nutrients

Q: ________ have/has existed since 4,000 years ago.
- Fermented drinks (Incorrect. It is likely the wine was first invented (or more likely discovered) about 4,500 years ago, while beer production began around 6,000 years ago.)
- Kimchi (Incorrect. Kimchi, or fermented cabbage, has existed since about 1,800 years ago.)
- Cultured milk products (Correct. Cultured milk products such as yogurt were definitely produced 4,000 years ago; cheese may be even older.)
A: Cultured milk products

Q: ________ is the process of utilizing prokaryotes to remove pollutants.
- Microbial vacuuming (Incorrect. This is not the term for using prokaryotes to remove pollutants.)
- Bacterial bioremediation (Incorrect. This term is not inclusive enough for the use of prokaryotes to remove pollutants from the environment.)
- Microbial bioremediation (Correct. Bioremediation can involve a host of prokaryotic organisms, not just bacterial species.)
A: Microbial bioremediation

Q: One of the most successful applications of bioremediation involves cleaning up ________.
- coal runoff (Incorrect. Cleaning up coal runoff is not the most successful use of microbial bioremediation.)
- Superfund sites (Incorrect. Cleaning up Superfund sites is not the most successful use of microbial bioremediation.)
- petroleum (Correct. Prokaryotic organisms have been particularly successful at cleaning up oil spills, degrading up to 80 percent of the nonvolatile compounds within one year of the spill.)
A: petroleum

Q: Bioremediation is not particularly effective at cleaning up ________ from oil spills.
- nonvolatile compounds (Incorrect. Petroleum bioremediation works well for nonvolatile compounds in oil.)
- simple hydrocarbon chains (Incorrect. Several species are able to breakdown simply hydrocarbon chains found in oil.)
- aromatic hydrocarbon chains (Correct. Petroleum bioremediation works well for nonvolatile compounds but not aromatic and highly branched hydrocarbons.)
A: aromatic hydrocarbon chains

Q: It has recently been discovered that microbial species appear to play a particularly strong role in the human ________ system.
- digestive (Incorrect. It has been known for many years that bacteria play a role in our digestive system.)
- integumentary (Incorrect. There are a host of microbes that live on our skin and play a role in pathogen defense, but this has been known for some time.)
- immune (Correct. Growing evidence appears to indicate that disruptions in our normal microbiota may contribute to autoimmune diseases and allergies.)
A: immune

Q: Clinical trials are underway to test the effectiveness of ________ for certain digestive disorders.
- antibiotics (Incorrect. Antibiotics will often disrupt the normal microbiota of the digestive system and actually contribute to disorders.)
- fungal transplants (Incorrect. Fungal organisms are not being tested as a therapeutic for digestive disorders.)
- fecal transplants (Correct. Fecal transplants would return normal, healthy microbiota to digestive systems that are impacted by antibiotic resistant bacteria.)
A: fecal transplants

Q: Some of our microbiota produce ________ for us.
- antigens (Incorrect. Antigens are produced only by our individual immune systems.)
- digestive enzymes (Incorrect. Microbiota in our digestive system may help digest some food, but they actually break down the food.)
- vitamins (Correct. Microbiota in our intestinal tract produce some vitamins such as biotin and folate that humans need and cannot produce on their own.)
A: vitamins