Prokaryotes play key roles in cycling elements such as carbon and nitrogen through ecosystems.
Correct Answer
True
True. Bacteria and archaea break down organic matter and carry out chemical conversions that return carbon and nitrogen to forms other organisms can use.
Category: Prokaryotic Diversity
Question 2
Extremophiles are bacteria and archaea adapted to harsh conditions such as very high temperature, salinity, or acidity.
Correct Answer
True
True. Extremophiles, meaning lovers of extremes, live in places such as hot springs, salt lakes, polar ice, and deep rock where most organisms cannot survive.
Category: Prokaryotic Diversity
Question 3
Bacteria in a biofilm are easier to kill with common sterilization methods than free-floating cells of the same species.
Correct Answer
False
False. Bacteria in a biofilm are protected by their sticky matrix and are much more resistant to disinfectants, antibiotics, and sterilization than free-floating (planktonic) cells.
Category: Prokaryotic Diversity
Question 4
Bioremediation uses microorganisms to remove pollutants such as spilled oil or toxic metals from the environment.
Correct Answer
True
True. Bioremediation harnesses microbial metabolism to clean up contaminants; for example, some bacteria break down oil after spills and others convert toxic mercury ions into a less harmful form.
Category: Prokaryotic Diversity
Question 5
Yogurt and sauerkraut are made with the help of fungi rather than bacteria.
Correct Answer
False
False. Both yogurt and sauerkraut are made by bacterial fermentation, in which lactic acid bacteria convert sugars into acid that thickens or preserves the food.
Category: Prokaryotic Diversity
Question 6
Mitochondria are surrounded by two membranes, which fits the idea that they arose when one cell engulfed another.
Correct Answer
True
True. The double membrane of mitochondria is consistent with endosymbiosis: the inner membrane resembles the engulfed bacterium's own membrane, and the outer one is thought to derive from the host.
Category: Endosymbiosis
Question 7
Mitochondria removed from a eukaryotic cell can survive and reproduce on their own.
Correct Answer
False
False. Although mitochondria descend from free-living bacteria, they have lost many of their genes over time and cannot survive outside the cell.
Category: Endosymbiosis
Question 8
Nearly all protists live in dry land habitats far from water.
Correct Answer
False
False. Nearly all protists live in water or in moist places such as damp soil and snow, and many others live inside hosts.
Category: Protist Biology
Question 9
Some protists can switch between photosynthesis and absorbing organic nutrients, depending on conditions.
Correct Answer
True
True. Organisms such as Euglena carry out photosynthesis in the light but can take in organic material when light is scarce, showing that protists are not limited to one mode of nutrition.
Category: Protist Biology
Question 10
A protist cyst is a resting stage with very low metabolism that can survive drying, extreme temperatures, and low pH.
Correct Answer
True
True. Cysts allow protists to wait out harsh conditions and can be spread by wind, water, or hosts until conditions improve.
Category: Protist Biology
Question 11
Photosynthetic protists such as diatoms and dinoflagellates contribute only a negligible share of the world's photosynthesis.
Correct Answer
False
False. Protists, especially diatoms, dinoflagellates, and multicellular algae, carry out roughly a quarter of the world's photosynthesis and form the base of many aquatic food webs.
Category: Protist Biology
Question 12
Coral bleaching occurs when corals take in extra photosynthetic dinoflagellates.
Correct Answer
False
False. Bleaching happens when stressed corals lose their photosynthetic dinoflagellate partners, leaving the coral pale and deprived of most of its energy supply.
Category: Protist Biology
Question 13
The malaria parasite Plasmodium is spread to humans by the bite of the tsetse fly.
Correct Answer
False
False. Plasmodium is transmitted by Anopheles mosquitoes. Tsetse flies carry Trypanosoma brucei, the cause of African sleeping sickness.
Category: Protist Pathogens
Question 14
Chagas disease is caused by a trypanosome that is spread by blood-sucking insects in Latin America.
Correct Answer
True
True. Trypanosoma cruzi is carried by blood-feeding bugs and can damage the heart and digestive tissues of infected people.
Category: Protist Pathogens
Question 15
Fungal plasma membranes contain ergosterol, which plays a role similar to cholesterol in animal cell membranes.
Correct Answer
True
True. Ergosterol stabilizes fungal membranes the way cholesterol stabilizes animal membranes, and it is a target of several antifungal drugs.
Category: Fungal Biology
Question 16
Most fungi are obligate anaerobes that cannot survive where oxygen is present.
Correct Answer
False
False. Most fungi are obligate aerobes that need oxygen. Only a few, such as certain chytrids in the cattle rumen, are obligate anaerobes.
Category: Fungal Biology
Question 17
Yeasts can carry out fermentation when oxygen is absent, producing alcohol and carbon dioxide.
Correct Answer
True
True. Yeasts are facultative anaerobes: with oxygen they use cellular respiration, and without it they ferment sugars into ethanol and carbon dioxide, which is why they are used in brewing and baking.
Category: Fungal Biology
Question 18
In mycorrhizae, the fungus supplies the plant with sugars while the plant supplies the fungus with minerals.
Correct Answer
False
False. The roles are the other way around: the plant gives the fungus sugars from photosynthesis, and the fungal hyphae supply the plant with water and minerals from the soil.
Category: Fungal Ecology and Disease
Question 19
Aflatoxins are cancer-causing compounds produced by Aspergillus molds that contaminate stored nuts and grains.
Correct Answer
True
True. Aflatoxins are toxic and carcinogenic, and contamination of nuts and grains by Aspergillus can lead to food recalls.
Category: Fungal Ecology and Disease
Question 20
Ringworm is a skin infection caused by a parasitic worm that burrows under the skin.
Correct Answer
False
False. Despite its name, ringworm is a fungal infection caused by dermatophytes that digest keratin in skin, hair, and nails, producing a red, ring-shaped lesion.
Category: Fungal Ecology and Disease