Micro Exam 2 - Mastering questions

Place the steps of root nodule formation in the correct order. 1. bacteroid formation 2. nod factor secretion 3. invasion 4. recognition of partners 5. mature nodule 1. 4, 2, 3, 1, 5 2. 4, 3, 2, 1, 5 3. 4, 2, 1, 3, 5 4. 4, 1, 2, 3, 5

1. 4, 2, 3, 1, 5

Microbes that thrive in acidic environments seem to have "cost free" ATP energy available to them due to the pre-existing H+ gradient across the cytoplasmic membrane. However, this is not entirely true because __________. 1. the protons entering the cell must be consumed to prevent the cytoplasm from becoming too acidic; therefore electrons are required as H+ are combined with O2 to form water 2. the protons from the acidic environment cannot be used for ATP production because they did not come from the inside of the cell 3. it requires energy to pump the protons into the cell to form the ATP 4. the protons would have to be pumped back out of the cell as fast as they came in through the ATPase, so as to avoid acidifying the cytoplasm. Therefore, no net energy would be captured

1. the protons entering the cell must be consumed to prevent the cytoplasm from becoming too acidic; therefore electrons are required as H+ are combined with O2 to form water

What is the function of the Calvin cycle in purple bacteria? 1. to incorporate inorganic carbon into an organic compound 2. to use sunlight to break down sugars 3. to break down sugars to harvest energy 4. to incorporate organic carbon into an inorganic compound

1. to incorporate inorganic carbon into an organic compound

Compounds that are NOT produced by organisms anywhere in nature are called __________. 1. xenobiotic 2. abiotic 3. foreign 4. xerobiotic

1. xenobiotic

A soil clump has an oxic (oxygen containing) zone containing aerobic and facultatively aerobic organotrophs, and an anoxic zone containing fermentative bacteria, sulfate reducers, and denitrifyers. This soil clump has at least __________ different habitats, __________ different communities and __________ different guilds. 1. 2, 2, 20 2. 2, 2, 5 3. 5, 5, 20 4. 5, 2, 5

2. 2, 2, 5

Since glucose, a hexose, is the major source of energy for most prokaryotes, why would they need to have pentose sugars available? 1. Pentose sugars are needed for transport processes. 2. Pentose sugars are needed for nucleic acid synthesis. 3. Pentose sugars are needed for protein synthesis. 4. Pentose sugars are needed for membrane synthesis.

2. Pentose sugars are needed for nucleic acid synthesis.

The term "respiration" is often used more broadly than is strictly accurate. The term "anaerobic respiration" may sound counterintuitive, but many different molecules can serve as electron donors or electron acceptors for prokaryotes. Which of the examples below is the best example of anaerobic respiration? 1. An organism uses an electron transport chain with sulfur as the terminal electron acceptor. 2. Lactic acid fermenters are able to generate energy in the absence of oxygen. 3. Purple bacteria use a type of photosynthesis that does not generate oxygen. 4. Many organisms use an electron transport chain with oxygen as the terminal electron acceptor to generate relatively large quantities of ATP.

1. An organism uses an electron transport chain with sulfur as the terminal electron acceptor.

Decomposition of organic carbon ultimately results in the formation of __________. 1. CO2 in aerobic environments and CO2 plus CH4 in anoxic environments 2. CO2 in aerobic environments and CH4 in anoxic environments 3. CO2 plus CH4 in aerobic environments and CH4 in anoxic environments 4. CH4 in aerobic environments and CO2 in anoxic environments

1. CO2 in aerobic environments and CO2 plus CH4 in anoxic environments

Distinguish how fermentation and respiration differ. 1. Fermentation forms organic acids and takes place in the absence of oxygen, while respiration forms water and carbon dioxide in the presence of oxygen. 2. Fermentation forms water and carbon dioxide and takes place in the presence of oxygen, while respiration forms water and carbon dioxide in the presence of oxygen. 3. Fermentation forms organic acids and takes place in the presence of oxygen, while respiration forms water and carbon dioxide in the presence of oxygen. 4. Fermentation forms water and carbon dioxide and takes place in the absence of oxygen, while respiration forms water and carbon dioxide in the presence of oxygen.

1. Fermentation forms organic acids and takes place in the absence of oxygen, while respiration forms water and carbon dioxide in the presence of oxygen.

What benefit does the fungal partner get from the lichen relationship? 1. The alga produces organic compounds as nutrients for the fungus. 2. The alga anchors the fungus to the substrate. 3. The alga facilitates water uptake. 4. The alga produces lichen acids that help provide inorganic nutrients from the substrate.

1. The alga produces organic compounds as nutrients for the fungus.

If an organism used glycolysis (Embden-Meyerhof-Parnas pathway) to break down glucose and produce ATP but was unable to subsequently use fermentation or an electron transport chain (respiration), what problem would develop? 1. The available NAD+ would be converted to NADH and glycolysis would eventually stop due to the lack of NAD+. 2. The cell will run out of ATP and glycolysis will stop. 3. The cell would run out of glucose and glycolysis would stop. 4. Glycolysis rates would increase in order to compensate for the lack of ATP produced by the other processes.

1. The available NAD+ would be converted to NADH and glycolysis would eventually stop due to the lack of NAD+.

Which statement below demonstrates why the majority of organisms are heterotrophs? 1. The majority of organisms obtain their carbon from organic sources. 2. The majority of organisms obtain their carbon from inorganic sources. 3. The majority of organisms conserve energy from inorganic sources and their carbon from organic sources. 4. The majority of organisms conserve energy from inorganic sources.

1. The majority of organisms obtain their carbon from organic sources.

The type of wastewater treatment that would be used to reduce the BOD (biological oxygen demand) of liquid waste would be __________. 1. aerobic activated sludge 2. anaerobic digestion 3. primary treatment 4. advanced tertiary treatment

1. aerobic activated sludge

The strategy for bioremediation of large sites contaminated by inorganic pollutants like toxic metals and radionuclides is usually to __________. 1. contain the pollutants by converting them into a less mobile form 2. break down the pollutants to less harmful products 3. completely oxidize the pollutants to carbon dioxide and water 4. completely remove the contaminants from the site

1. contain the pollutants by converting them into a less mobile form

Denitrification contributes to global warming by __________. 1. destroying ozone 2. decreasing the amount of organic nitrogen in the soil 3. increasing soil pH 4. increasing the amount of carbon dioxide released

1. destroying ozone

Trace elements are found in bacterial cells in very small amounts because they __________. 1. function only in a limited set of enzymes and cofactors 2. are not essential to cell function 3. are toxic to the cell 4. are only found in limited quantities in the environment

1. function only in a limited set of enzymes and cofactors

Many nutrient cycles are coupled and changes in one cycle will affect another. This means that a change in the amount of carbon dioxide fixed is intimately affected by the amount of __________. 1. nitrogen available in an ecosystem 2. hydrogen available in an ecosystem 3. methane available in an ecosystem 4. oxygen available in an ecosystem

1. nitrogen available in an ecosystem

Fermentation occurs when there is no usable external electron acceptor (like O2) available for respiration. Fermentation products are made following glycolysis as a result of reactions that __________. 1. oxidize NADH so that NAD+ can be reused again in glycolysis 2. generate more ATP energy from the substrate 3. synthesize more NAD+ from substrate molecules 4. get rid of toxic waste products generated during glycolysis

1. oxidize NADH so that NAD+ can be reused again in glycolysis

The role of an enzyme includes all EXCEPT which of the following? 1. reducing the rate of a reaction to allow for better control 2. straining chemical bonds in a substrate so that they break easier 3. binding only one specific substrate to the enzyme active site 4. lowering the activation energy of a reaction

1. reducing the rate of a reaction to allow for better control

Inorganic compounds can be reduced by microbes either for biosynthesis (assimilatory reductions) or for energy metabolism (dissimilative reductions) purposes. What is the role of the inorganic compound that is reduced in dissimilative reductions? 1. As sources of elemental substances for use in making proteins or nucleic acids 2. As terminal electron acceptors for anaerobic respiration 3. As electron donors for anaerobic respiration 4. As electron carriers for any type of respiration

2. As terminal electron acceptors for anaerobic respiration

To calculate the free energy (ΔG0′) of a reaction, you can subtract the free energies of formation (Gf0) of the reactants from those of the products. Given the following data, what will be true of this reaction? C6H12O6 + O2 → CO2 + H2O; Gf0 : -917.3 0 -394.4 -237.2 1. The reaction will not require a catalyst to proceed. 2. The reaction will be exergonic. 3. The reaction is not balanced, so you cannot calculate the change in free energy. 4. The reaction will be endergonic.

2. The reaction will be exergonic.

The function of NAD+/NADH in the cell is best described as __________. 1. a way to transport electrons to the mitochondria for energy generation in bacteria 2. a way to increase the types of redox reactions that occur in the cell by acting as an intermediary between dissimilar compounds 3. a way to increase the types of redox reactions that occur in the cell by acting as an intermediary between similar compounds 4. a way to transport protons to the plasma membrane for energy generation in bacteria

2. a way to increase the types of redox reactions that occur in the cell by acting as an intermediary between dissimilar compounds

While most of the oil spilled into the Gulf of Mexico from the Deepwater Horizon drilling rig in 2010 has disappeared, some of the oil spilled from the Exxon Valdez oil tanker into Prince William Sound, Alaska, in 1989 still remains in the coastal sand and sediments. What possible differences in these two spills could account for the different rates of petroleum degradation? 1. seawater salt composition and types of bacteria 2. ambient temperatures and the types of hydrocarbons present 3. the amount of oil spilled and the seawater salts composition 4. the types of bacteria present and the amount of oxygen in the water

2. ambient temperatures and the types of hydrocarbons present

Increases in atmospheric carbon dioxide concentrations leads to acidification of the oceans as CO2 dissolves in the water and forms carbonic acid. This acidification is predicted to have a major effect on the carbon cycle, as well as the calcium and silica cycles, due to the roles of Ca+ and Si in __________. 1. mercury oxidation 2. building the shells and frustules of microscopic algae and some animals 3. the formation of fossil fuels 4. the formation of carbonate rocks

2. building the shells and frustules of microscopic algae and some animals

Autotrophs are always __________. 1. mixotrophs 2. chemolithotrophs 3. heterotrophs 4. chemotrophs

2. chemolithotrophs

Geobacter sulfurreducens uses its pili to form direct connections with insoluble ferric iron particles. As the organism carries out respiration, the Fe3+ is acting as a(n) __________. 1. micronutrient 2. electron acceptor 3. electron donor 4. carbon source

2. electron acceptor

Which of the following would NOT be required to grow an autotroph? 1. potassium phosphate 2. glucose 3. water 4. trace elements

2. glucose

Organic micronutrients are commonly called __________. 1. trace metals 2. growth factors 3. trace elements 4. growth elements

2. growth factors

Carbon dioxide and methane are potent greenhouse gases, with methane having 20 times more warming potential in the atmosphere than CO2. As global warming progresses, there is the real possibility that increased temperatures on land and in the oceans will lead to a positive feedback effect leading to accelerated warming. From the carbon reservoirs listed below with their percentage of the total carbon on Earth, what would be the most dangerous potential source of C that could be released to potentiate further warming? 1. oceans and terrestrial biosphere (0.053%) 2. methane hydrates (0.014%) 3. rocks and sediments (99.5%) 4. fossil fuels (0.006%)

2. methane hydrates (0.014%)

According to ecological theory, each organism has one place where it will be most successful, called the __________. 1. fundamental niche 2. realized niche 3. guild 4. microenvironment

2. realized niche

Advanced wastewater treatment includes __________. 1. adding organic matter 2. removing additional suspended solids 3. removing only organic matter 4. adding inorganic nutrients for microbial growth

2. removing additional suspended solids

One characteristic of a biofilm is __________. 1. the presence of a cellulose matrix to hold the organisms together 2. the presence of one or more species of bacteria 3. bacteria do not have to be attached to a surface 4. a single layer of cells

2. the presence of one or more species of bacteria

Phosphorus is cycled like carbon, nitrogen, and sulfur, except for the fact that __________. 1. there are only oxidation reactions during transformations 2. there are no gaseous forms that can alter the chemistry in the atmosphere 3. there are only reduction reactions during transformations 4. there are only gaseous forms that can alter the chemistry in the atmosphere

2. there are no gaseous forms that can alter the chemistry in the atmosphere

Whether a molecule is oxidized or reduced in a redox reaction depends on its reduction potential relative to the available electron donors and acceptors present that the organism can utilize. Given the following reduction potentials for various redox half reactions, in a lithotroph capable of utilizing ammonia as an energy source, which substances would be potential terminal electron acceptors for respiration? NO2 -/NH3 +0.34 V NO3 -/NO2 - +0.43 V O2/H2O +0.82 V 1. O2 2. NO3 - 3. Both O2 and NO3 - are possible electron acceptors 4. NO2 -

3. Both O2 and NO3 - are possible electron acceptors

Some organisms are capable of using aerobic respiration or anaerobic respiration but use aerobic respiration preferentially. Why is aerobic respiration favored? 1. Aerobic respiration generates more oxygen, which is needed by many organisms. 2. Using aerobic respiration allows them to use fermentation as well. 3. Respiration with oxygen as a terminal electron acceptor generates more energy than respiration with other terminal electron acceptors. 4. It is more efficient to focus on one process than to use two simultaneously, so aerobic respiration is the default and anaerobic respiration is used only as a backup.

3. Respiration with oxygen as a terminal electron acceptor generates more energy than respiration with other terminal electron acceptors.

Why would using nitrogenous fertilizer near a body of water affect the organisms in the body of water? 1. It would not affect the organisms in the water, only those in the soil where the fertilizer is applied. 2. When runoff enters the body of water, the nitrogen level significantly increases, which decreases the activity of the microorganisms there and upsets the balance of the ecosystem. 3. When runoff enters the body of water, the nitrogen level significantly increases, which increases the activity of the microorganism there and upsets the balance of the ecosystem. 4. When runoff enters the body of water, the nitrogen level significantly decreases, which increases the activity of the microorganisms there and upsets the balance of the ecosystem.

3. When runoff enters the body of water, the nitrogen level significantly increases, which increases the activity of the microorganism there and upsets the balance of the ecosystem.

The function of NAD+/NADH in the cell is best described as __________. 1. a way to increase the types of redox reactions that occur in the cell by acting as an intermediary between similar compounds 2. a way to transport protons to the plasma membrane for energy generation in bacteria 3. a way to increase the types of redox reactions that occur in the cell by acting as an intermediary between dissimilar compounds 4. a way to transport electrons to the mitochondria for energy generation in bacteria

3. a way to increase the types of redox reactions that occur in the cell by acting as an intermediary between dissimilar compounds

Microbial mats differ from biofilms in that they __________. 1. have different environmental conditions at various depths within the community 2. contain more than one species of microorganism in the community 3. are currently found only in extreme habitats 4. are found only attached to surfaces

3. are currently found only in extreme habitats

A defined culture medium is designed to meet the needs of a particular type of organism, suppling all of the nutrients the organism needs, including essential biochemicals that the cell cannot synthesize. Based on the following recipe, this defined medium would best support the growth of certain members of what group? Recipe: 7 g of K2HPO4; 2 g of KH2PO4; 1g of (NH4)2SO4; 0.1g of MgSO4; 0.02g of CaCl2; 10g of glucose; trace elements mix; 1000 mL of distilled water; adjust to pH 7. 1. chemolithotroph 2. autotroph 3. chemoorganotroph 4. phototroph

3. chemoorganotroph

The type of mycorrhizae found associated with forest trees like pines is __________. 1. endomycorrhizae 2. none because not all plants form mycorrhizal associations 3. ectomycorrhizae 4. arbuscular mycorrhizae

3. ectomycorrhizae

Sulfate reduction (SO42- → H2S) occurs only where organic material is abundant because __________. 1. the bacteria require more energy to reduce sulfate 2. the organic material is used to detoxify the H2S 3. electrons from organic compounds are necessary for this reaction 4. sulfate comes from organic material

3. electrons from organic compounds are necessary for this reaction

In anoxic environments, organic compounds are cycled back to carbon dioxide and methane by __________. 1. metabolism 2. glycolysis 3. fermentation 4. cellular respiration

3. fermentation

Benefits of a nodulated plant include __________. 1. decreased oxygen produced through photosynthesis 2. decreased nitrogen available to the plant 3. increased plant yield due to nitrogen fixation 4. increased oxygen produced through photosynthesis

3. increased plant yield due to nitrogen fixation

As nutrients cycle in the biosphere, __________ can participate in every transformation from one chemical form of a nutrient to another. 1. plants 2. animals 3. prokaryotes 4. fungi

3. prokaryotes

Microbial diversity in an ecosystem can be expressed as the number of different species present, which is termed __________. 1. species abundance 2. microbial community 3. species richness 4. microbial population

3. species richness

Termites are capable of digesting cellulose and hemicellulose due to the presence of __________. 1. enzymes that digest these compounds 2. endosymbiotic bacteria 3. symbiotic bacteria in their gut 4. none of the listed responses

3. symbiotic bacteria in their gut

A major reservoir for calcium is __________. 1. marine sediment 2. diatoms 3. the ocean 4. freshwater sediment

3. the ocean

Applying your knowledge of metabolism, glycolysis starts with one molecule of glucose (6C) and produces a net total of __________. 1. two pyruvates; 4 NADH; 2 ATP 2. one pyruvate; 2 NADH; 4 ATP 3. two pyruvates; 2 NADH; 2 ATP 4. one pyruvate; 2 NADH; 2 ATP

3. two pyruvates; 2 NADH; 2 ATP

If the citric acid cycle was interrupted after the reaction that forms citrate, predict how this would affect the total amount of ATP generated per glucose molecule. 1. The amount of ATP would be reduced from a total of 38 ATP to 30 ATP. 2. The amount of ATP would be reduced from a total of 38 ATP to 8 ATP. 3. The amount of ATP would be reduced from a total of 38 ATP to 22 ATP. 4. The amount of ATP would be reduced from a total of 38 ATP to 14 ATP.

4. The amount of ATP would be reduced from a total of 38 ATP to 14 ATP.

How is anaerobic respiration different from aerobic respiration? 1. The two processes are identical. The only difference is the presence or absence of oxygen. 2. The terminal electron acceptor in anaerobic respiration is oxygen. 3. The terminal electron acceptors are the same, but the chemical reactions are different. 4. The terminal electron acceptor in anaerobic respiration is not oxygen.

4. The terminal electron acceptor in anaerobic respiration is not oxygen.

Why is U4+ a preferred form of uranium over U6+? 1. Uranite is insoluble; U4+ is soluble. 2. U6+ is insoluble, which makes it difficult to work with. 3. U4+ is soluble, so it can move from its initial site to other places and be diluted by groundwater. 4. U4+ is insoluble, so it will not contaminate groundwater.

4. U4+ is insoluble, so it will not contaminate groundwater.

All of the following are true of biofilms EXCEPT that __________. 1. biofilm formation and dispersal are regulated processes 2. biofilms form on virtually all submerged surfaces in nature 3. biofilms protect organisms from antibiotics 4. biofilms are composed of only one species at a time

4. biofilms are composed of only one species at a time

Environmental damage due to acid mine drainage occurs only once ores containing pyrite (FeS2) are __________. 1. mixed with other toxic metals like lead and cadmium 2. reduced from Fe3+ to Fe2+ oxidation states 3. increased in temperature to at least 50 degrees C. 4. exposed to oxygen and water

4. exposed to oxygen and water

Bacteria, such as Leptothrix, must have a mechanism to manage the end products when utilizing iron for oxidation, because __________. 1. ferrous iron is insoluble and will build up in or on the cell 2. A large amount of energy can be conserved from the oxidation of ferric iron to ferrous iron. 3. A large amount of energy can be conserved from the oxidation of ferrous iron to ferric iron. 4. ferric iron is insoluble and will build up in or on the cell

4. ferric iron is insoluble and will build up in or on the cell

Human influences on the carbon cycle may cause major upsets in the balance of the ecosystem because __________. 1. increasing the anthropogenic carbon dioxide released in the atmosphere is significantly increasing the pH of the oceans 2. increasing the anthropogenic carbon dioxide released in the atmosphere may significantly increase the amount of ozone in the atmosphere 3. increasing the anthropogenic carbon dioxide released in the atmosphere is decreasing the temperature of the oceans 4. increasing the anthropogenic carbon dioxide released in the atmosphere may significantly decrease the amount of calcium carbonate in the deep ocean

4. increasing the anthropogenic carbon dioxide released in the atmosphere may significantly decrease the amount of calcium carbonate in the deep ocean

Initiation of biofilm formation in many organisms is at least in part regulated by c-di-GMP, which alters gene expression and enzyme activity leading to all of the following EXCEPT __________. 1. formation of cell surface attachment proteins 2. initiation of extracellular polysaccharide production 3. production of intercellular signaling molecules 4. initiation of flagella formation

4. initiation of flagella formation

Bacteria will benefit as part of a biofilm because __________. 1. it allows all compounds in the environment to diffuse to the organism's location much faster 2. it allows them to be phagocytosed easier 3. it allows them to live separated from other bacteria 4. it allows them to remain in a favorable niche

4. it allows them to remain in a favorable niche

Both ammonium (NH4+) and nitrate (NO3-) are assimilated by primary producers, but ammonium is the preferred form of nitrogen for fertilizers used in agriculture because __________. 1. ammonium does not cause eutrophication (algal blooms) if it enters aquatic ecosystems 2. ammonium leaches out of soils easily due to its positive charge 3. ammonium is converted to nitrate by microbial nitrification 4. nitrate leaches out of soils easily due to its negative charge

4. nitrate leaches out of soils easily due to its negative charge

Physical separation of solids and organic and inorganic particulates from sewage is termed __________. 1. secondary waste water treatment 2. sand filtration 3. tertiary wastewater treatment 4. primary wastewater treatment

4. primary wastewater treatment

Electron carriers used in electron transport chains are always found in membranes. Which one of the following statements is NOT a reason why electron transport chains are found in membranes? 1. So that electron-only carriers can be arranged to alternate with electron-plus-proton carriers in the chain. 2. so that they can efficiently pass electrons in sequence from the carriers with the more negative reduction potentials to those with the more positive reduction potentials 3. so that the electron carriers can be oriented within the membrane such that protons are passed from one side of the membrane to the other 4. so that they can transport NADH out of the cell to the periplasm

4. so that they can transport NADH out of the cell to the periplasm

Microorganisms are capable of producing products that can harm the integrity of __________. 1. concrete and metals only 2. metals only 3. stone and metals only 4. stone, concrete, and metals

4. stone, concrete, and metals

The proton motive force (PMF) is driven by __________. 1. the difference in charge across the plasma membrane with electrons outside the membrane 2. the pumping of electrons though the plasma membrane 3. the pumping of protons through the plasma membrane 4. the difference in charge across the plasma membrane with protons outside the membrane

4. the difference in charge across the plasma membrane with protons outside the membrane

The reduction potential (E0′) of a substance reflects its tendency to donate or accept electrons. The larger the difference (ΔE0′) between the reduction potentials of the electron donor and the electron acceptor, __________. 1. the greater the change in free energy (ΔG0′), and the less energy is released 2. the more enzymes will be required to catalyze the reaction(s) 3. the closer the substances are on the electron tower 4. the greater the change in free energy (ΔG0′), and the greater the energy released

4. the greater the change in free energy (ΔG0′), and the greater the energy released

Compared with pure cultures grown in the lab, microbes in nature usually experience a wider range of environmental conditions, more variation in conditions over time, and more contact with other organisms. Therefore, the same organism in nature will __________. 1. carry out completely different metabolisms than in pure culture 2. typically grow faster than in pure culture 3. typically grow only on surfaces 4. typically grow slower than in pure culture

4. typically grow slower than in pure culture