When prokaryotes live as interacting communities in which one population benefits to the harm of the other, the type of symbiosis is called parasitism.
Missing Word
parasitism
Parasitism is a symbiotic relationship where one organism (the parasite) benefits at the expense of the other (the host). This interaction can lead to harm or disease in the host organism.
Question 2
The domain Eukarya does not include prokaryotes.
Missing Word
Eukarya
The domain Eukarya encompasses all eukaryotic organisms, characterized by cells with a nucleus and other membrane-bound organelles. Prokaryotes, lacking these features, belong to the domains Bacteria and Archaea.
Question 3
Pathogenic bacteria that are part of the transient microbiota can sometimes be eliminated by antibiotic therapy.
Missing Word
antibiotic
Transient microbiota are microorganisms that temporarily reside on or in the host and can be eliminated by factors like antibiotic therapy. Unlike the resident microbiota, they do not permanently colonize the host.
Question 4
Nitrogen-fixing bacteria provide other organisms with usable nitrogen in the form of ammonia.
Missing Word
ammonia
Nitrogen-fixing bacteria convert atmospheric nitrogen gas (N2) into ammonia (NH3), a form of nitrogen that plants and other organisms can utilize. This process is essential for the nitrogen cycle and overall ecosystem health.
Question 5
Rickettsias are obligate intracellular bacteria.
Missing Word
obligate
Rickettsias are obligate intracellular parasites, meaning they require a host cell to replicate. They lack key metabolic pathways and rely on the host cell for essential nutrients and energy, making 'obligate' the correct descriptor.
Question 6
The species Helicobacter pylori, which belongs to Epsilonproteobacteria, causes peptic ulcers of the stomach and duodenum.
Missing Words
Helicobacter, pylori
Helicobacter pylori is a spiral-shaped bacterium within the Epsilonproteobacteria class known for colonizing the stomach and duodenum. Its unique ability to survive in the acidic environment of the stomach, facilitated by urease production, leads to peptic ulcers, thus identifying 'Helicobacter pylori' as the correct answer.
Question 7
The genus Salmonella belongs to the class Gammaproteobacteria and includes pathogens that cause salmonellosis and typhoid fever.
Missing Word
Gammaproteobacteria
Salmonella is a genus of Gram-negative bacteria classified within the Gammaproteobacteria class. This group contains many medically relevant bacteria, including Salmonella species responsible for foodborne illnesses like salmonellosis and the more severe typhoid fever, making 'Gammaproteobacteria' the appropriate classification.
Question 8
The bacterium that causes syphilis is called Treponema pallidum pallidum.
Missing Word
Treponema pallidum pallidum
Treponema pallidum pallidum is the specific subspecies of Treponema pallidum that causes syphilis. It is a spirochete bacterium with a characteristic corkscrew shape and is transmitted through sexual contact, leading to the systemic infection known as syphilis.
Question 9
Bacteria in the genus Rhodospirillum that use hydrogen for oxidation and fix nitrogen are purple nonsulfur bacteria.
Missing Words
purple, nonsulfur
Purple nonsulfur bacteria, like Rhodospirillum, are a group of phototrophic bacteria that can use hydrogen as an electron donor for photosynthesis and are capable of nitrogen fixation. They are distinguished from purple sulfur bacteria by their ability to grow in the absence of sulfur compounds.
Question 10
Streptococcus is the genus of bacteria that is responsible for many human diseases.
Missing Word
genus
Streptococcus is a significant genus of Gram-positive bacteria known for causing a wide range of human diseases. These diseases range from mild infections like strep throat to severe conditions like pneumonia and sepsis, highlighting the importance of 'genus' in identifying this group.
Question 11
One species of Streptococcus, S. pyogenes, is a classified as a pyogenic pathogen due to the characteristic production of pus in infections it causes.
Missing Word
pyogenic
Pyogenic bacteria are those that induce the formation of pus, a thick fluid containing dead cells and bacteria, at the site of infection. Streptococcus pyogenes is a prime example, causing infections characterized by pus production, thus classifying it as a 'pyogenic' pathogen.
Question 12
Cutibacterium belongs to high G+C gram-positive bacteria. One of its species is used in the food industry and another causes acne.
Missing Word
high
Cutibacterium, formerly Propionibacterium, belongs to the high G+C Gram-positive bacteria, characterized by a high guanine and cytosine content in their DNA. Certain species are used in food production, while others, like Cutibacterium acnes, are associated with acne, thus making 'high' the correct descriptor.
Question 13
The length of the branches of the evolutionary tree characterizes the evolutionary distance between organisms.
Missing Word
distance
In phylogenetic trees, the length of the branches represents the amount of evolutionary change or genetic divergence between organisms. Longer branches indicate a greater accumulation of mutations and therefore a larger evolutionary 'distance'.
Question 14
The deeply branching bacteria are thought to be the form of life closest to the last universal common ancestor.
Missing Words
common, ancestor
Deeply branching bacteria are considered to be among the earliest diverging lineages from the bacterial domain, closest to the root of the tree of life. Their characteristics are thought to resemble those of the last universal 'common ancestor' (LUCA) from which all life on Earth is derived.
Question 15
Many of the deeply branching bacteria are aquatic and hyperthermophilic, found near underwater volcanoes and thermal ocean vents.
Missing Word
vents
Deeply branching bacteria, often extremophiles, thrive in harsh environments. Underwater volcanoes and thermal ocean vents provide the high temperatures and unique chemical conditions that support their survival.
Question 16
The deeply branching bacterium Deinococcus radiodurans is able to survive exposure to high doses of ionizing radiation.
Missing Words
ionizing, radiation
Deinococcus radiodurans possesses remarkable DNA repair mechanisms. These mechanisms allow it to withstand and recover from the damaging effects of ionizing radiation, which would be lethal to most other organisms.
Question 17
Sulfolobus is a genus of Archaea. Its optimal environmental temperature ranges from 70 °C to 80 °C, and its optimal pH is 2–3. It oxidizes sulfur and produces sulfuric acid.
Missing Word
Sulfolobus
Sulfolobus is a genus of archaea known for its thermoacidophilic properties. Its metabolism involves sulfur oxidation, leading to the production of sulfuric acid, which contributes to its acidic environment.
Question 18
Methanobrevibacter oralis was once thought to be the cause of periodontal disease, but, more recently, the causal relationship between this archaean and the disease was not confirmed.
Missing Words
Methanobrevibacter, oralis
Methanobrevibacter oralis is an archaeon found in the human oral cavity. While initially suspected in periodontal disease, further research has not definitively established it as a primary causative agent.