BIOL-111 Chapter 9 Homework

The free energy for the oxidation of glucose to CO₂ and water is -686 kcal/mol, and the free energy for the reduction of NAD⁺ to NADH is +53 kcal/mol. Why are only two molecules of NADH formed during glycolysis when it appears that as many as a dozen could be formed?

• Glycolysis is a very inefficient reaction, with much of the energy of glucose released as heat.

• There is no carbon dioxide or water produced as products of glycolysis.

• Most of the free energy available from the oxidation of glucose remains in pyruvate, one of the products of glycolysis.

• Most of the free energy available from the oxidation of glucose is used in the production of ATP in glycolysis.

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

•   fermentation and glycolysis

•   oxidative phosphorylation and fermentation

•   oxidation of pyruvate to acetyl CoA and the citric acid cycle

•   glycolysis and the oxidation of pyruvate to acetyl CoA

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

•   30-32

•   18-24

• 4

• 2

Use the image shown to answer the following:  If pyruvate oxidation is blocked, what will happen to the levels of oxaloacetate (OAA) and citric acid (citrate) in the citric acid cycle shown in the accompanying figure?

•   Both oxaloacetate and citric acid will decrease.

•   Oxaloacetate will decrease and citric acid will accumulate.

•   Both oxaloacetate and citric acid will accumulate.

•   Oxaloacetate will accumulate and citric acid will decrease.

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

•   the breakdown of an acetyl group to carbon dioxide

•   the breakdown of glucose into six carbon dioxide molecules

•   substrate-level phosphorylation

What kinds of cells carry out ATP synthesis by chemiosmosis?

•   all respiring cells, both prokaryotic and eukaryotic, using either oxygen or other electron acceptors

•   all cells, both prokaryotic and eukaryotic, exclusively using oxygen as the electron acceptor

•   only animal cells in mitochondria, exclusively using oxygen as the electron acceptor

•   only eukaryotic cells, both plant and animal, using either oxygen or other electron acceptors

In liver cells, the inner mitochondrial membranes are about five times the area of the outer mitochondrial membranes. What purpose must this serve?

•   It increases the surface for oxidative phosphorylation.

•   It increases the surface for substrate-level phosphorylation.

•   It allows for an increased rate of glycolysis.

•   It allows for an increased rate of the citric acid cycle.

In organisms that perform aerobic respiration, which of the following metabolic processes normally occurs regardless of whether or not oxygen (O₂) is present?

• glycolysis

•   oxidative phosphorylation

•   citric acid cycle

•   lactate fermentation

In eukaryotic cells, where are the proteins of the electron transport chain located?

•   mitochondrial outer membrane

•   mitochondrial matrix

•   mitochondrial intermembrane space

•   mitochondrial inner membrane

Which of the following statements describes a primary function of both alcohol fermentation and lactic acid fermentation?

•   reduction of NAD+ to NADH

•   reduction of FAD to FADH2 (the 2 should be subscripted; Canvas will not allow this)

•   hydrolysis of ATP to ADP + Pi

•   oxidation of NADH to NAD+