Questions and All Correct Answers
2025-2026 Updated.
Mycorrhizae are a symbiotic association of - Answer plant roots and fungi
Which of the following involve symbiotic relationships? - Answer rhizobia, mycorrhizae, AND
ruminants
Which of the following statements regarding microbial identification is false? - Answer
Culture techniques are an accurate way of determining which members in a microbial
community are most common.
Next to carbon and oxygen, the element organisms most require is - Answer nitrogen.
Which statement describes the relationship between ammonia oxidizers and nitrite oxidizers? -
Answer Ammonium oxidizers use ammonium as an energy source, oxidizing it to nitrate. The
nitrate produced then serves as the energy source for nitrite oxidizers.
Gardeners sometimes plant clover between productive growing seasons. Why would this
practice be beneficial? - Answer Several types of nitrogen-fixing bacteria form a symbiotic
relationship with the roots of clover. This would increase the amount of nitrogen in the soil
available for subsequent seasons of other plants' growth.
Sulfur occurs in all living matter primarily as a component of - Answer amino acids.
The region of the earth inhabited by living organisms is called the - Answer biosphere
Nitrifiers - Answer convert nitrate to nitrite.
WRONG
Truffles - Answer form a sheath around a root of an appropriate tree.
Azotobacter - Answer are the chief suppliers of fixed nitrogen in grasslands.
Which of the following is not a matching pair? - Answer Soil—minimal biodiversity
, Sulfur occurs in all living matter primarily as a component of carbohydrates. - Answer False
The practice of cells turning on the production of some enzymes and turning off others in
response to a changing environment is called - Answer adaptation
The organic matter in soil is referred to as - Answer humus
How do bacteriocins benefit bacteria in their natural habitat? - Answer They allow bacteria
to compete against other bacteria that may attempt to use the same or similar resources.
Eutrophic waters - Answer are nutrient rich AND may become hypoxic.
The organisms that convert carbon dioxide into organic matter are the - Answer producers
No eukaryotic organisms have been shown to fix nitrogen without the aid of prokaryotes. -
Answer True
Biofilms are likely to be found in environments - Answer with low nutrients
Which statement is FALSE? - Answer Removal of nitrates by microorganisms requires aerobic
conditions.
A high BOD value means - Answer a large amount of oxygen has been used AND a large
amount of degradable organic matter is present.
The term "potable water" refers to water that is - Answer safe to drink
Vibrio cholerae is most often associated with - Answer drinking water
Pollutant degradation may be enhanced by - Answer providing adequate nutrients.
Trickling filters may be used in place of activated sludge in secondary sewage treatment. -
Answer True
Which of the following cannot be used in composting? - Answer Meats and fats