Module 4 Assessment: CH21-22

Distinguish among amensalism, commensalism, mutualism, parasitism, and synergism.

[A]: two organisms grow in an intimate species-specific relationship in which both partner species benefit and require each other for survival.

[B]: Both species benefit through growth, but the partners are easily separated and either partner can grow independently of the other.

[C]: One species benefits, while the partner species neither benefits nor is harmed.

[D]: One species benefits by harming another. The relationship is nonspecific.

[E]: One species (the parasite) benefits at the expense of the other (the host). The relationship is usually obligatory/specific for the parasite.

[A] Mutualism [B] Synergism [C] Commensalism [D] Amensalism [E] Parasitism

State some contributions of the commensal gut microbiome to human health. Which of these is correct?

• All but two

• All but one

• Human gut microbes communicate with their host.

• All

• Commensal members help digest dietary fiber.

• Commensal bacteria send chemical signals to our immune tissues and to our brain.

• Commensal members of the gut microbe normally outcompete pathogens.

• Commensal members help boost immune system.

All

Explain why all ecosystems require microbes.

The bacteria in soil and water can conduct photosynthesis without utilizing oxygen, using electron donors such as H2S instead of H2O, introducing microbial metabolism. Moreover, microbial metabolism provides ecosystems with their sole source of key elements such as sulfur, phosphorus, and iron. Microbes cycle essential nutrients through metabolism.

True/False

True

Determine the type of symbiotic relationship for each of the following organisms. Use one of these keys: amensalism; commensalism; mutualism, synergism; parasitism.

Escherichia coli O157:H7 and human host ____[A]__________

Rhizobium and plant host ____[B]_______

Aeromonas hydrophila and channel catfish _____[C]_________

Vibrio cholerae and copepods (shellfish) ___[D]__________

[A] Parasitism [B] Mutualism [C] Amensalism [D] Commensalism

Distinguish the global reservoirs of carbon, nitrogen, and sulfur. Which of these is correct?

• Carbon: Ocean

     Nitrogen: Atmospheric nitrogen gas

     Sulfur: Atmospheric H2S gas

• Carbon: Atmospheric CO2

     Nitrogen: Atmospheric N2

     Sulfur: Atmospheric H2S gas

Carbon: Ocean

Nitrogen: Atmospheric nitrogen gas

Sulfur: Atmospheric H2S gas

Explain why many marine microbes are uncultured.

Often, microbial growth requires hidden synergy or mutualism with other organisms in the natural environment.

True/False

True

Outline the sulfur, phosphorous, and iron cycles. Which of these is incorrect?

• Phosphorus: weathering, absorption by plants and animals, and return to the environment via decomposition.

• Sulfur cycle: decomposition of organic compounds, oxidation of hydrogen sulphide to elemental sulphur, oxidation of elemental sulphur, and reduction of sulphates.

• Iron: oxidized iron serves as a terminal electron acceptor in anaerobic soil and water. Iron Cycles- In the presence of O2, iron metal (Fe0) rusts and is therefore available to microorganisms (i.e., bacteria) mainly as Fe2+(ferric ion).

• None

Iron: oxidized iron serves as a terminal electron acceptor in anaerobic soil and water. Iron Cycles- In the presence of O2, iron metal (Fe0) rusts and is therefore available to microorganisms (i.e., bacteria) mainly as Fe2+(ferric ion).

Contrast assimilation and dissimilation.

[A] is an organism’s acquisition of an element, such as carbon from CO2, to build into body parts. [B] is an organism’s catabolism or oxidation of nutrients to inorganic minerals that are released into the environment.

[A] Assimilation [B] Dissimilation

Summarize the factors contributing to atmospheric CO2 levels. Which of these is correct?

• Respiration

• Microbial decomposition of dead material in the soil

• All but one

• Fossil fuel burning

• Transpiration

• All

• All but two

• Photosynthesis

All but two

Identify carbon sources and sinks.

Carbon sources are forest fires, burning fossil fuel, and photosynthesis.

Carbon sinks are oceans, plants, and soil

True/False

true

Explain why nitrogen is often a limiting nutrient in ecosystems and what happens when this limitation is removed.

Nitrogen is a highly stable molecule that requires an enormous input of reducing energy before assimilation is possible. Thus, for many natural ecosystems, and most forms of agriculture, nitrogen is the limiting nutrient for primary productivity. If this limitation is removed, plants would grow as tall or as rapidly. Most plants require fixed nitrogen in order to grow. This is why nitrogen is a primary ingredient in plant fertilizers.

true/false

True

Define niche and biomass.

[A] is an organism’s environmental requirements for existence and its relations with other members of the ecosystem. [B] is the mass found in the bodies of living organisms.

[A] Niche [B] Biomass

Categorize different types of fungus–plant interactions. Use of these keys: ectomycorrhizae; endomycorrhizae.

There is a mycorrhizae, which is fungi involved in an intimate mutualism with plant roots, in which nutrients are exchanged. [A], where mycorrhizae that colonize the surface of plant roots. Their mycelia do not penetrate the root cells. [B], which is mycorrhizae whose fungal hyphae penetrate plant root cells. And then there’s arbuscular mycorrhizae, where mutualistic associations between plant roots and certain fungi, involving hyphal penetration of plant root cells.

[A] Ectomycorrhizae [B] Endomycorrhizae

Identify limitations of SSU rRNA sequencing and metagenomic analysis. Which of these statements is correct?

• Metagenomes does not tell the expression of a gene.

• Metagenomes does not tell the spatial organization and interaction of microbes within a habitat.

• All but one

• All

• Metagenomes may miss community members.

All

Define metagenome, microbiome.

A microbiome is the total community of microbes associated with an organism or with a defined habitat.

True/False

True

Outline the nitrogen cycle. Which of these is correct?

• Nitrogen fixation, nitrogen assimilation, and ammonification

• Nitrogen assimilation, ammonification, nitrification, and denitrification

• Nitrogen fixation, nitrogen assimilation, ammonification, and denitrification

• Nitrogen fixation, nitrogen assimilation, ammonification, and nitrification

Nitrogen fixation, nitrogen assimilation, ammonification, and denitrification

State the properties of the different soil horizons. Use one of these keys: aerated horizon; bedrock; eluviated horizon; organic horizon; water-saturated horizon.

• The surface layer of soil we see is the [A]. This horizon consists of dark, organic detritus, such as shreds of leaves fallen from plants, and microbial decomposer, primarily fungi and bacteria such as actinomycetes.

• In the [B], the source of the organic particles is no longer recognizable, and decomposers have broken down some of the more difficult-to-digest plant structural components, such as lignin.

• The [C] experiences leaches minerals from above. Rainwater dissolves and removes some of the organic and mineral nutrients from the upper layers.

• The lower layers are [D]: form water table. In anoxic conditions, lithotrophs and anaerobes grow in here.

• The soil layers finally end at [E]. Crustal rock as deep as 3 km down contains endoliths.

[A] organic horizon [B] aerated horizon [C] eluviated horizon [D] water-saturated horizon [E] bedrock

Identify nitrogen sources and sinks.

Sinks of nitrogen: atmosphere and ocean

Sources of nitrogen: rock, atmospheric precipitation, agricultural land, and livestock waste.

True/False

False

Explain how humans are responsible for increased environmental CO2 levels and their consequences. Which of these is correct?

• Rising carbon dioxide concentrations will cause global warming.

• Rising carbon dioxide concentrations will increase greenhouse effect.

• Humans are responsible for increased environmental CO2 levels due to the industrial burning of fossil fuels.

• Humans are responsible for increased environmental CO2 levels due to the burning of fossil fuels in order to have gasoline for cars and generate electricity.

• All

• All but one

• All but two

All

Evaluate the role of microbes in wastewater treatment.

Wastewater treatment plant is a microbiological zoo that houses bacteria, protozoa, metazoa and other microlife. These micro-organisms breakdown and remove nutrients and organic material in the wastewater.

True/False

True

Identify factors that control the biochemical oxygen demand (BOD). Which of these statements is incorrect?

• All but one

• The open ocean usually has a low concentration, which means the BOD is low.

• Eutrophication can contribute to the decreasing of BOD.

• The concentration of heterotrophic microorganisms determines the biochemical oxygen demand (BOD), amount of oxygen removed from the water by microbial aerobic respiration.

• None

• All but two

• The BOD rises when excess sewage or petroleum is present.

Eutrophication can contribute to the decreasing of BOD.

State how oxygen levels influence carbon cycling.

The carbon cycle gives off oxygen for the oxygen cycle to use and in turn, the oxygen cycle emits carbon dioxide which goes back into the carbon cycle. Plants are the main connection between the oxygen and carbon cycles.

True/False

True

Differentiate the three sides of the nitrogen triangle and describe what happens in each. Use one of these keys: denitrification; nitrification; nitrogen fixation.

The nitrogen triangle is composed of three parts: atmospheric N2, the reduced forms of NH3 and NH4+, and the oxidized forms of NO2- and NO3-. In the first side, the [A] to ammonium, a form assimilated into biomass by microbes and plants. In the second side, [B], the oxidation of ammonia, in which ammonia is oxidized aerobically to nitrite and nitrate. Last, [C] of nitrate and nitrite back to nitrogen.

[A] nitrogen fixation [B] nitrification [C] denitrification

Recall the biological roles of sulfur, phosphorous, and iron.

Sulfur: Found in DNA

Phosphorus: Found in nucleic acids

Iron: Found in red blood cells

True/False

False