Micro Ch. 5 exam 1

According to the animation, which compounds provide electrons to the system? ANSWER: NADH and FADH2 NADH Oxygen Water FADH2

a

Microbes are often identified using biochemical tests that detect specific enzymes of metabolic pathways. E.coli typically ferments lactose, whereas the dysenterybacterium, Shigella, does not. If a pure culture of each bacterium were placed in a tube containing lactose as the only food source, and a chemical indicator changed color if the tube became acid, what would the tubes look like after the bacteria were incubated? ANSWER: The tube with E. coli would indicate a pH change, and the Shigella tube would indicate no change. Neither tube will show any change. Both tubes would show the evidence of lactose fermentation by turning acidic and changing the pH indicator. Both tubes would show the evidence of lactose fermentation by turning alkaline.

a

Much of the energy released in catabolic reactions is captured in ATP for use in other reactions. When the phosphate is transferred directly from an organic molecule to ADP in order to produce ATP, as represented by C--C--C ~P + ADP → C--C--C + ATP, this represents __________. ANSWER: substrate-level phosphorylation oxidative phosphorylation noncyclic photophosphorylation cyclic photophosphorylation

a

The process of generating ATP using a proton gradient is referred to as ANSWER: chemiosmosis. water damming. the electron transport chain.

a

When proteins are oxidized, all of the following are true EXCEPT which one? ANSWER: Microbes produce extracellular enzymes to reduce proteins to their fatty acid and glycerol components so that each component can enter the Krebs cycle. After deamination of the protein, the organic acid enters the Krebs cycle. The amino group is removed through deamination and converted to nitrogenous waste such as NH4+. Enzymes break down proteins into component amino acids.

a

Where would you expect to find electron transport chains in a prokaryote? ANSWER: Along the plasma membrane Along the outer mitochondrial membrane Along the inner mitochondrial membrane Along the cell wall Free-floating in the cytoplasm

a

Which of the following statements about glycolysis is true? ANSWER: Glycolysis is also called the Embden-Meyerhof pathway. Glycolysis is the main source of NADH in the cell. Glycolysis produces glucose. All cells perform glycolysis.

a

Why is ATP required for glycolysis? ANSWER: ATP makes it easier to break apart glucose into two three-carbon molecules. ATP is used to convert PEP into pyruvic acid. ATP is used to convert DHAP into G3P. ATP is used to reduce NAD+ to NADH.

a

According to the animation, what does oxygen get reduced to at the end of the electron transport chain? ANSWER: Protons Water NADH Electrons ATP

b

According to the animation, what does the electron transport chain do to the concentration of hydrogen ions (protons)? ANSWER: The concentration of protons is lower outside the membrane than inside. The concentration of protons is higher outside the membrane than inside. The concentration of protons inside the membrane is equal to the concentration outside of the membrane.

b

Based on the animation, how many electron carriers are reduced in the Krebs cycle only? ANSWER: Three Four Six Five

b

Based on the concept map only, which of the following is most likely to be true of microbial metabolism? ANSWER: Acetyl-CoA is converted directly into 2 ATP The Krebs cycle produces molecules necessary for function of the electron transport chain. The energy from 2 ATP is necessary to drive the electron transport chain. Acetyl-CoA is produced by substrate-level phosphorylation.

b

What is the function of GTP? ANSWER: An oxidizer to produce CO2 An energy carrier A scaffolding for carbon atoms An electron carrier

b

What is the intermediate product formed by pyruvic acid during alcoholic fermentation? ANSWER: Lactic acid Acetaldehyde Formic acid Carbon dioxide Ethanol

b

What is the role of pyruvic acid in fermentation? ANSWER: It becomes the final electron acceptor for the electron transport chain in the absence of oxygen. It takes the electrons from NADH, oxidizing it back into NAD+. It provides the protons to be used in the electron transport chain. It is the organic acid end-product of fermentation.

b

What occurs at the bridge step? ANSWER: The formation of oxaloacetate Decarboxylation of pyruvic acid The formation of succinyl CoA The production of GTP

b

Which of the following correctly matches enzyme components with their correct definition and/or function? ANSWER: Cofactors are the protein components of enzymes. Coenzymes are the organic cofactors important to enzyme activity. Apoenzymes are typically inorganic molecules, such as iron, zinc, or magnesium. Apoenzymes are the nonprotein component of an enzyme.

b

Which of the following statements about fermentation is true? ANSWER: It provides additional protons to allow the electron transport chain to continue. It is an alternative way to return electron carriers to their oxidized state. It is an alternative way for a cell to produce oxygen. It allows the electron transport chain to continue in the abs

b

A new antibiotic is produced that inhibits the synthesis of acetyl-CoA and the electron transport chain in bacteria. For each glucose molecule that is metabolized, how many fewer ATP molecules will be produced? ANSWER: 38 4 36 34 2

c

What is the fate of the NAD+ newly regenerated by fermentation? ANSWER: It is converted into an organic acid. It is oxidized into carbon dioxide. It returns to glycolysis to pick up more electrons. It is converted into ethanol.

c

Which of the following is an acid produced by fermentation? ANSWER: Ethanol Propionic acid Lactic acid and propionic acid Lactic acid Pyruvic acid

c

Glycolysis literally means ANSWER: sugar producing. energy producing. Embden-Meyerhof. sugar splitting.

d

How many net ATPs can be made from one molecule of glucose in glycolysis? ANSWER: Four Six One Two

d

What carbon molecules remain at the end of glycolysis? ANSWER: Glyceraldehyde 3-phosphate (G3P) Dihydroxyacetone phosphate (DHAP) Glucose Pyruvic acid

d

What is the fate of metabolites during respiration? ANSWER: They are oxidized completely to form pyruvic acid. They are reduced to from NADH and FADH2. They are rearranged to form GTP. They are oxidized completely to carbon dioxide and water.

d

Which of the following conditions would increase enzymatic activity in a bacterial cell that normally thrives in the human body? ANSWER: increasing the substrate level in the environment beyond saturation adding another substrate that can act as a competitive inhibitor placing the bacteria in the refrigerator slightly increasing the temperature within the optimum range

d

Which of the following is true of aerobic respiration compared to anaerobic respiration? ANSWER: Aerobic respiration uses oxygen as a final electron (hydrogen) acceptor, whereas anaerobic respiration uses an organic molecule. Aerobic respiration and anaerobic respiration both require oxygen as a final electron acceptor. Aerobic respiration is less efficient than all forms of anaerobic respiration, producing less ATP and largerend-products. Aerobic respiration uses oxygen as a final hydrogen acceptor, whereas anaerobic respiration uses an inorganic molecule other than oxygen as the final electron acceptor.

d

Which of the following processes directly produce the most ATP? ANSWER: Glycolysis the Krebs cycle synthesis of acetyl-CoA the electron transport chain

d