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WorksheetsChapter 4 Microbio
Total questions: 27
Worksheet time: 14mins
Which step in the nitrogen cycle involves bacteria converting nitrates (NO3−) into gaseous nitrogen (N2), thereby returning nitrogen to the atmosphere?
Nitrogen fixation
Nitrification
Denitrification
Ammonification
Fill in the blank with the specific chemical product: During nitrogen fixation, nitrogen-fixing bacteria convert atmospheric nitrogen (N2) into (a) .
An ecosystem manager wants to enhance plant nitrogen availability in a peanut field. Based on the described Rhizobium symbiosis steps, which intervention would most strategically support successful nodule formation and nitrogen acquisition? Choose the best option that aligns with the sequence provided.
Apply nitrifying bacteria to oxidize ammonia to nitrites, accelerating nitrogen supply
Encourage root hair flavonoid release to attract rhizobia, facilitating infection thread formation
Add denitrifying bacteria to convert nitrates to nitrogen gas, increasing atmospheric nitrogen
Introduce halophiles like Halobacterium salinarum to decompose organic matter in saline soil
A plant biologist is investigating early root events that lead to effective Rhizobium symbiosis in legumes. Which ordered pair best represents the first two sequential steps described for rhizobial infection?
Root hair curls due to rhizobia; flavonoids are released to attract rhizobia
Flavonoids attract rhizobia; root hair curls and forms an infection thread
Infection thread grows into root cortex; bacterial cells become bacteroids
Fungal hyphae grow toward the root; arbuscules form in the cortex
Which sequence best explains how plants actively initiate nutrient exchange structures with fungi during mycorrhizal interactions?
Plants produce strigolactones that stimulate fungal hyphae growth toward the root, leading to arbuscule formation in the root cortex for nutrient exchange.
Fungi release strigolactones to attract plant roots, which then form arbuscules for nutrient exchange.
Plants secrete arbuscules that attract fungal hyphae, which then produce strigolactones for nutrient exchange.
Fungi form arbuscules outside the root, and plants respond by producing strigolactones for nutrient exchange.
The microbiome is defined as the ecological community of all prokaryotic and eukaryotic microorganisms that share a particular space. Which of the following best describes the types of organisms included in the microbiome, and does the human body qualify as a space hosting a microbiome?
It includes both prokaryotes and eukaryotes, and the human body qualifies as a space hosting a microbiome.
It includes only prokaryotes, and the human body does not qualify as a space hosting a microbiome.
It includes only eukaryotes, and the human body qualifies as a space hosting a microbiome.
It includes viruses only, and the human body does not qualify as a space hosting a microbiome.
Which statement best distinguishes resident microbiota from transient microbiota, using the exact terms provided?
Resident microbiota are microorganisms that are consistently present; transient microbiota are only temporarily present.
Resident microbiota are only temporarily present; transient microbiota are consistently present.
Resident microbiota consist solely of prokaryotes; transient microbiota include eukaryotes.
Resident microbiota live only on the skin; transient microbiota live only in the gut.
Sergei Winogradsky was instrumental in studying soil microbes and the nitrogen cycle. He developed the Winogradsky Column to cultivate diverse microbial communities in a way that mimics a natural environment. Why is the Winogradsky Column relevant to studying microbial communities?
It creates stratified conditions and nutrient gradients that allow different microbes to grow as they would in nature.
It is used to study only a single type of microbe in isolation.
It eliminates all nutrient gradients to create a uniform environment.
It is primarily used for studying plant growth, not microbes.
Select all correct statements about the importance of the microbiome based on the content.
It helps educate the immune system to distinguish between beneficial and harmful microbes.
Gut microbes provide essential nutrients; for example, E. coli produces vitamin K2 and B12.
A healthy microbiome competes with pathogens for resources, preventing infections from establishing.
The gut microbiome has no influence on mental health because it does not connect to the brain.
Dysbiosis in the gut microbiota is linked to obesity, cardiovascular disease, IBS, and cognitive decline; Lactobacillus reuteri could prevent weight gain with a high-fat Western diet in mice.
Gram-Positive Bacteria stain _______ in a Gram stain, and the cell envelope consists of the _______ and _______.
(a)
According to the content, which feature is characteristic of Gram-negative bacteria?
Thick peptidoglycan with teichoic acids
Waxy mycolic acid layer in cell walls
Thin peptidoglycan layer and an outer membrane containing lipopolysaccharide (LPS)
Lack of a cell wall
Fill in the blank: Acid-fast bacteria contain a waxy lipid called (a) in their cell walls and require a special stain for visualization.
Which statement best explains why β-proteobacteria can be challenging to culture, based on the provided notes?
They are described as often difficult to culture because they can be “fastidious,” meaning they have specific, demanding growth requirements.
They are resistant to antibiotics, making them hard to grow in labs.
They grow rapidly and outcompete other bacteria, making isolation difficult.
They require high temperatures to grow, which is hard to maintain in the lab.
Which organisms are explicitly listed as examples within γ-proteobacteria? Select all that apply.
Escherichia
Salmonella
Yersinia
Myxobacteria
Helicobacter pylori
Which Gram-negative phylum is described as having spiral-shaped bacteria that are thin and highly motile due to an internal axial filament?
Proteobacteria
Spirochetes
Bacteroides
Actinobacteria
Identify the correct pairing of organism and disease as given in the material.
Treponema pallidum — Lyme disease
Bordetella pertussis — whooping cough
Campylobacter — stomach ulcers
Helicobacter pylori — food poisoning from poultry
Within δ-proteobacteria, which two examples are provided, and what key characteristics are highlighted for each?
Bdellovibrio is noted as a predatory bacterium that attacks other gram-negative bacteria; Myxobacteria can form complex, multicellular “fruiting bodies.”
Bdellovibrio is a photosynthetic bacterium; Myxobacteria are known for nitrogen fixation.
Bdellovibrio forms fruiting bodies; Myxobacteria are predatory on gram-positive bacteria.
Bdellovibrio is a gram-positive bacterium; Myxobacteria are unicellular.
Which health conditions are associated with the genera Campylobacter and Helicobacter pylori in the ε-proteobacteria group?
Campylobacter is a leading cause of food poisoning from poultry, and Helicobacter pylori is associated with stomach ulcers.
Campylobacter causes respiratory infections, and Helicobacter pylori is linked to skin rashes.
Campylobacter is associated with urinary tract infections, and Helicobacter pylori causes liver disease.
Campylobacter leads to bone fractures, and Helicobacter pylori is linked to diabetes.
Which statement about Bacteroides is accurate based on the text?
They are Gram-positive aerobes common in soil.
They are Gram-negative, obligate anaerobes that are a major component of the human gut microbiome.
They are acid-fast bacteria requiring an acid-fast stain.
They are bioluminescent symbionts of marine squids.
If shown a diagram with an outer membrane labeled “LPS” and a thin peptidoglycan layer, which staining result should you expect, and what feature supports this conclusion?
Expect a pink Gram stain result; the presence of a thin peptidoglycan layer and an outer membrane containing LPS indicates a Gram-negative bacterium.
Expect a purple Gram stain result; the thick peptidoglycan layer and absence of LPS indicate a Gram-positive bacterium.
Expect a pink Gram stain result; the presence of a waxy layer and thick peptidoglycan indicate an acid-fast bacterium.
Expect a purple Gram stain result; the presence of an outer membrane and LPS indicate a Gram-positive bacterium.
Phototrophic bacteria use light for energy. Based on the distinctions provided, which statement correctly contrasts Cyanobacteria with Purple & Green Bacteria?
Cyanobacteria perform anoxygenic photosynthesis using hydrogen sulfide as an electron donor.
Cyanobacteria perform oxygenic photosynthesis producing O2, while Purple & Green Bacteria perform anoxygenic photosynthesis that does not produce O2.
Both Cyanobacteria and Purple & Green Bacteria are evolutionary ancestors of chloroplasts.
Purple & Green Bacteria cause harmful water blooms and are ancestors of chloroplasts.
A lake has harmful blooms. Identify the likely bacterial group and justify with specific characteristics from the material.
Cyanobacteria; they perform oxygenic photosynthesis and are known to form harmful blooms in water.
Purple sulfur bacteria; they use hydrogen sulfide for photosynthesis and do not produce oxygen.
Green nonsulfur bacteria; they thrive in hot springs and do not typically cause blooms in lakes.
Heliobacteria; they are found in soils and do not form blooms in aquatic environments.
Which pathogen is correctly paired with the disease it causes according to the content on Gram-positive phyla?
Mycobacterium leprae — tetanus
Corynebacterium diphtheriae — diphtheria
Clostridium difficile — leprosy
Streptococcus pyogenes — botulism
Deinococcus radiodurans is considered a polyextremophile because it is extremely resistant to which of the following combinations of conditions?
Heat, drought, vacuum, and radiation
Only high temperatures
Only acidic environments
Only high salinity
Within the major groups of Archaea, identify the environment and metabolic trait pairing that is correctly matched.
Crenarchaeota — halophiles performing bacteriorhodopsin-based photosynthesis
Euryarchaeota methanogens — produce methane (CH4) in marshes and ruminant guts
Crenarchaeota methanogens — thrive in extremely salty environments
Euryarchaeota Sulfolobus — thrives in vacuum and radiation
Fill in the blank: The halophile Halobacterium salinarum can perform a type of photosynthesis using (a) .
A microbiologist isolates an archaeal organism from an acidic, high-temperature hot spring. Which major archaeal group does it most likely belong to, and what specific example from the content supports your conclusion?
Crenarchaeota; Sulfolobus is an example thriving in such environments.
Euryarchaeota; Methanogens are found in acidic, high-temperature springs.
Korarchaeota; Halobacterium is an example from these environments.
Nanoarchaeota; Thermoplasma is commonly found in acidic, high-temperature springs.
