Exam 3 Compilation

Which of the following forms of nitrogen could be taken in by cells and converted into usable nitrogen? - Urea - Ammonium - All of these - Nitrogen gas - Nitrate

- All of these

Which compounds that are essential to the cell cannot be formed by simply modifying carbon precursors - Amino acids - Fatty Acids - Cell walls - Polysaccharides

- Amino acids

Any form of nitrogen incorporated into the cell must first be converted into _____ before being assimilated into biomass. - Nitrogen gas - Any of these - Nitrate - Urea - Ammonium

- Ammonium

The nif Operon is turned on when ______. - Cellular nitrogen is high; oxygen is absent - Cellular nitrogen is low; oxygen is absent - Cellular nitrogen is high; oxygen is present - Cellular nitrogen is low; oxygen is present

- Cellular nitrogen is high; oxygen is absent

Which statement regarding the foundational principles of microbial ecology is DEFINITELY false? - From elephant to butyric acid bacterium - it is all the same - Every molecule existing in nature can be used as a source of carbon or energy by a microorganism somewhere. - Microbes are found in every environment on Earth. - Everything is everywhere, and the environment selects

- Everything is everywhere, and the environment selects

T/F: All phototrophs are autotrophs. - True - False

- False

What would be a cell's preferred way to acquire a specific amino acid? - Fix it from nitrogen gas. - Build it from precursor molecules. - Build it from scratch. - Import it directly from outside the cell.

- Import it directly from outside the cell.

Where is the major global sink of phosphorous stored? - In the atmosphere - In biomass - In geological formations (i.e. rocks) - In the ocean

- In geological formations (i.e. rocks)

How do sulfur oxidizers differ from nitrogen oxidizers? - Sulfur has no major impacts on its surrounding environment. - Sulfur compounds cannot be used as an electron acceptor - Individual organisms can typically oxidize a variety of sulfur species - Sulfur only has one oxidation state, so it is a less versatile donor

- Individual organisms can typically oxidize a variety of sulfur species

Why is oxygen in the cell unwelcome for diazotrophs? - It irreversibly damages the enzyme necessary for nitrogen fixation. - They are all obligate anaerobes. - It allows respiration to compete with nitrogen fixation for resources in the cell. - They lack superoxide dismutase or similar enzymes necessary for protection from reactive oxygen species.

- It irreversibly damages the enzyme necessary for nitrogen fixation.

Which statement regarding iron as an electron donor is false? - It is typically coupled with oxygen as an acceptor - It can require reverse electron flow to generate NAD(P)H - It does not yield much energy - It is a good electron donor

- It is a good electron donor

Which of the following could not be used as an electron donor for chemolithotrophs? - Ammonium - Nitrite - Ammonium - Nitrate

- Nitrate

Photophosphorylation with the primary goal of making energy, but not producing compounds for biosynthesis is called _______. - Cyclic - Non-cyclic - Oxidative - Substrate-level

- Non-cyclic

Methanogenesis can generate energy because ______. - Methane is a powerful energy source. - Non-standard conditions create favorable energetics. - Using oxygen, any compound can be energetically favorable as an electron donor. - Hydrogen is a good enough electron donor that it can be coupled with carbon dioxide.

- Non-standard conditions create favorable energetics.

Identify the false statement regarding biosynthesis. - Biosynthesis is energetically costly. - Biosynthesis is necessary for the generation of many cellular products. - Most biosynthetic pathways rely on the conversion of carbon into precursor molecules. - Only autotrophs conduct biosynthesis.

- Only autotrophs conduct biosynthesis.

All of the following are necessary for the Calvin Cycle to occur - EXCEPT - Rubisco - Oxygen - ATP - Carbon Dioxide

- Oxygen

Reduced sulfur is available for: - Respiration only - Chemotrophy Only - Phototrophy and Chemotrophy - Phototrophy Only

- Phototrophy and Chemotrophy

Which statement regarding Rhodopsins is false? - They are found in both archaea and some bacteria - They pass protons out of the cell due to conformational changes - They absorb the same wavelengths as chlorophylls - They can help to generate ATP via a proton motive force

- They absorb the same wavelengths as chlorophylls

What is shared by all of the Carbon fixation pathways? - They all produce glucose directly. - They all use energy to reduce carbon dioxide. - They all share enyzmes with other pathways. - They all depend on solar energy.

- They all use energy to reduce carbon dioxide.

Identify the false statement about chemolithoautotrophs - They do not conduct oxidative phosphorylation - They can often be autotrophic or heterotrophic - They can often be aerobic or anaerobic - They can often switch between lithotrophy and organotrophy

- They do not conduct oxidative phosphorylation

Which statement regarding photophosphorylation involving chlorophylls is FALSE? - Low energy electrons are excited within the photosystems - Different photosystems can contain different pigments which are excited by varying wavelengths. - Water is the only electron donor for photosystems - Light harvesting complexes can be organized to maximize the energy gained

- Water is the only electron donor for photosystems

T/F: All phototrophs are autotrophs. -True -False

False

Photophosphorylation with the primary goal of making energy, but not producing compounds for biosynthesis is called _______. - Non-cyclic - Cyclic - Oxidative - Substrate-level

Non-cyclic