Bio Exam 2

25 July 2022
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question
Which of the following statements best describes the central role that ATP plays in cellular metabolism?
answer
ATP provides energy coupling between exergonic and endergonic reactions.
question
Glycolysis results in the net production of which of the following sets of molecules per glucose molecule?
answer
two pyruvate molecules, two ATP molecules, and two NADH molecules for the cell to use for energy.
question
Which of the following statements best describes an exergonic reaction?
answer
The reaction proceeds with a net release of free energy.
question
Upon completion of the citric acid cycle, most of the energy originally stored in each glucose molecule catabolized by cellular respiration is stored in which of the following molecules?
answer
NADH
question
Which of the following statements best describes a characteristic of NAD+?
answer
NAD+ is reduced to NADH in glycolysis, pyruvate oxidation, and the citric acid cycle.
question
Which of the summary statements below best describes the results of the following reaction?C6H12O6 + 6O2 →→ 6CO2 + 6H2O + Energy
answer
C6H12O6 is oxidized and O2 is reduced.
question
An enzyme-catalyzed reaction has a ΔG of -20 kcal/mol under standard conditions. What will be the ΔG for the reaction if the amount of enzyme is doubled?
answer
-20 kcal/mol
question
Which of the following statements best describes enzyme function?
answer
Enzymes increase the rate of chemical reactions by lowering activation energy barriers.
question
Which of the following statements best describes catabolic pathways?
answer
They are exergonic and provide energy that can be used to produce ATP from ADP and Pi.
question
When electrons are passed from one atom to a more electronegative atom, the more electronegative atom is ________
answer
reduced, and energy is released
question
Which of the following statements best describes what happens to a molecule of NAD+ (nicotinamide adenine dinucleotide) when it gains a hydrogen atom?
answer
NAD+ becomes reduced.
question
Which of the following reactions produces the majority of the CO2 released by the complete oxidation of glucose?
answer
the citric acid cycle
question
Which of the following is a characteristic feature of anabolic pathways?
answer
They consume energy to build up polymers from monomers.
question
In which reactions of cellular respiration does substrate-level phosphorylation occur?
answer
in both glycolysis and the citric acid cycle
question
Which of the following products result from the oxidation of pyruvate to acetyl-CoA?
answer
NADH and CO2
question
The standard free energy for the complete oxidation of glucose to CO2 and water is -686 kcal/mol, and the standard free energy for the reduction of NAD+ to NADH is +53 kcal/mol. Which of the following statements best explains why only two molecules of NADH are formed in glycolysis when up to 12 molecules could theoretically be produced?
answer
Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.
question
A decrease in entropy is associated with which of the following types of reaction?
answer
dehydration
question
The citric acid cycle. For each mole of glucose (C6H12O6) oxidized by cellular respiration, how many moles of CO2 are released in the citric acid cycle?
answer
4
question
Which of the following statements best describes how addition of a catalyst will affect a chemical reaction?
answer
The catalyzed reaction will have the same ΔG as the uncatalyzed reaction. Catalysts (both enzymes and non-biological catalysts) act by lowering G+. Catalysts DO NOT CHANGE G. All they do is lower the energy required to activate the reaction. While enzymes speed reactions immensely, they therefore DO NOT CHANGE THE OVERALL REACTION CONCENTRATION AT EQUILIBRIUM.
question
If glucose is the sole energy source for cellular respiration in an animal, what proportion of the carbon dioxide exhaled is derived from oxidation of pyruvate to acetyl CoA?
answer
1/3