Ch 9 - Cellular Respiration and Fermentation

Which of the following statements best describes the primary role played by oxygen in cellular respiration?

It serves as the final acceptor for electrons from the electron transport chain.

Starting with one molecule of glucose, glycolysis results in the net production of which of the following sets of energy-containing products?

2 NADH, 2 pyruvate, and 2 ATP

Starting with citrate, which of the following combinations of products would result from three acetyl CoA molecules entering the citric acid cycle?

3 ATP, 6 CO2, 9 NADH, and 3 FADH2

Approximately how many molecules of ATP are produced from the complete oxidation of one molecule of glucose (C6H12O6) in aerobic cellular respiration?

30 - 32

For each mole of glucose (C6H12O6) oxidized by cellular respiration, how many moles of CO2 are released in the citric acid cycle (see the accompanying figure)?

4

Which one of the following is formed by the removal of a carbon (as CO2) from a molecule of pyruvate?

acetyl CoA

Which of the following statements about the electron transport chain is true?

It consists of a series of redox reactions

Why is glycolysis considered to be one of the first metabolic pathways to have evolved?

It does not involve organelles or specialized structures, does not require oxygen, and is present in most organisms.

In the absence of oxygen, yeast cells can obtain energy by fermentation, which results in the production of which of the following sets of molecules?

ATP, CO2, and ethanol (ethyl alcohol)

Substrate-level phosphorylation accounts for approximately what percentage of the ATP formed by the reactions of glycolysis?

100%

Which of the following statements describes what happens to a molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction?

It loses electrons and loses potential energy.

Following glycolysis and the citric acid cycle, but before the electron transport chain and oxidative phosphorylation, the carbon skeleton of glucose has been broken down to CO2 with some net gain of ATP. Most of the energy from the original glucose molecule at that point in the process, however, is stored in the form of which of the following molecules?

NADH

Which electron carrier(s) function in the citric acid cycle?

NADH and FADH2

If pyruvate oxidation is blocked, what will happen to the levels of oxaloacetate and citric acid in the citric acid cycle shown in the accompanying figure?

Oxaloacetate will accumulate and citric acid will decrease.

What happens when electrons are passed from one atom to a more electronegative atom?

The more electronegative atom is reduced, and energy is released.

High levels of citric acid inhibit the enzyme phosphofructokinase, a key enzyme in glycolysis. Citric acid binds to the enzyme at a different location from the active site. This is an example of _____.

allosteric regulation

Which kind of metabolic poison would most directly interfere with glycolysis?

an agent that closely mimics the structure of glucose but is not metabolized

The synthesis of ATP by oxidative phosphorylation, using the energy released by movement of protons across the membrane down their electrochemical gradient, is an example of which of the following processes?

coupling of an endergonic reaction to an exergonic reaction

In chemiosmosis, what is the most direct source of energy that is used to convert ADP +Pi to ATP?

energy released from movement of protons through ATP synthase, down their electrochemical gradient

Which of the following sequences describes the path by which electrons travel downhill energetically in aerobic respiration?

glucose → NADH → electron transport chain → oxygen

Where are the proteins of the electron transport chain located?

mitochondrial inner membrane

Energy released by the electron transport chain is used to pump H+ ions into which location in eukaryotic cells?

mitochondrial intermembrane space

Carbon dioxide (CO2) is released during which of the following stages of cellular respiration?

oxidation of pyruvate to acetyl CoA and the citric acid cycle

During which of the following metabolic processes is most of the CO2 from the catabolism of glucose is released?

the citric acid cycle

Which of the following events takes place in the electron transport chain?

the harnessing of energy from high-energy electrons derived from glycolysis and the citric acid cycle