Campbell Chapter 9: Mastering Biology Questions
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Questions and Answers

In muscle cells, fermentation produces ____.

lactate and NAD+

Which term describes the degree to which an element attracts electrons?

Electronegativity

Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other?

Anion and cation

Which of the following statements is true of the bonds in a water molecule?

<p>Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero.</p> Signup and view all the answers

Which of the following statements is not true of most cellular redox reactions?

<p>A hydrogen atom is transferred to the atom that loses an electron.</p> Signup and view all the answers

What kind of bond is formed when lithium and fluorine combine to form lithium fluoride?

<p>Ionic</p> Signup and view all the answers

In the reaction 2H2 + O2 → 2H2O + energy, which molecule is oxidized and what kind of bond is formed?

<p>Hydrogen, polar</p> Signup and view all the answers

Which of the following best describes the main purpose of the combined processes of glycolysis and cellular respiration?

<p>Transforming the energy in glucose and related molecules in a chemical form that cells can use for work</p> Signup and view all the answers

In the combined processes of glycolysis and cellular respiration, what is consumed and what is produced?

<p>Glucose is consumed, and carbon dioxide is produced.</p> Signup and view all the answers

Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions?

<p>ATP and NADH only</p> Signup and view all the answers

Which of the following describes the process of glycolysis?

<p>It represents the first stage in the chemical oxidation of glucose by a cell.</p> Signup and view all the answers

How many NADH are produced by glycolysis?

<p>2</p> Signup and view all the answers

In glycolysis, ATP molecules are produced by ____.

<p>substrate-level phosphorylation</p> Signup and view all the answers

Which of these is NOT a product of glycolysis?

<p>FADH2</p> Signup and view all the answers

In glycolysis, what starts the process of glucose oxidation?

<p>ATP</p> Signup and view all the answers

In glycolysis there is a net gain of _____ ATP.

<p>2</p> Signup and view all the answers

In the oxidation of pyruvate to acetyl CoA, one carbon atom is released as CO2. However, the oxidation of the remaining two carbon atoms—in acetate—to CO2 requires a complex, eight-step pathway—the citric acid cycle. Consider four possible explanations for why the last two carbons in acetate are converted to CO2 in a complex cyclic pathway rather than through a simple, linear reaction.

<p>It is easier to remove electrons and produce CO2 from compounds with three or more carbon atoms than from a two-carbon compound such as acetyl CoA.</p> Signup and view all the answers

What happened to most of the energy that the cell obtains from the oxidation of glucose?

<p>It is stored in NADH and FADH2.</p> Signup and view all the answers

Which of these enters the citric acid cycle?

<p>Acetyl CoA</p> Signup and view all the answers

In the citric acid cycle, ATP molecules are produced by ____.

<p>substrate-level phosphorylation</p> Signup and view all the answers

Which of these is NOT a product of the citric acid cycle?

<p>Acetyl CoA</p> Signup and view all the answers

Which statement about the citric acid cycle is correct?

<p>The last reaction in the citric acid cycle produces a product that is a substrate for the first reaction of the citric acid cycle.</p> Signup and view all the answers

The electrons stripped from glucose in cellular respiration end up in which compound?

<p>Water</p> Signup and view all the answers

In mitochondrial electron transport, what is the direct role of O2?

<p>To function as the final electron acceptor in the electron transport chain.</p> Signup and view all the answers

How would anaerobic conditions (when no O2 is present) affect the rate of electron transport and ATP production during oxidative phosphorylation?

<p>Both electron transport and ATP synthesis would stop.</p> Signup and view all the answers

Which statement best explains why more ATP is made per molecule of NADH than per molecule of FADH2?

<p>Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor.</p> Signup and view all the answers

Which one of the following statements about the redox reactions of the electron transport chain is correct?

<p>The redox reactions of the electron transport chain are directly coupled to the movement of protons across a membrane.</p> Signup and view all the answers

In fermentation _____ is reduced and _____ is oxidized.

<p>Pyruvate...NADH</p> Signup and view all the answers

In the absence of oxygen, what is the net gain of ATP for each glucose molecule that enters glycolysis?

<p>Two ATP</p> Signup and view all the answers

What happens to the carbon in compounds that do not end up as CO2?

<p>The carbon compounds are removed from these processes to serve as building blocks for other complex molecules.</p> Signup and view all the answers

What is the oxidizing agent in the following reaction, Pyruvate + NADH + H+ → Lactate + NAD+?

<p>Pyruvate</p> Signup and view all the answers

The immediate energy source that drives ATP synthesis by ATP synthase during oxidative phosphorylation is the ____.

<p>H+ concentration across the membrane holding ATP synthase.</p> Signup and view all the answers

Which metabolic pathway is common to both fermentation and cellular respiration of a glucose molecule?

<p>Glycolysis</p> Signup and view all the answers

In mitochondria, exergonic redox reactions provide the energy that establishes the ____.

<p>proton gradient.</p> Signup and view all the answers

The final electron acceptor of the electron transport chain that functions in aerobic oxidative phosphorylation is ____.

<p>Oxygen.</p> Signup and view all the answers

When electrons flow along the electron transport chains of mitochondria, which of the following changes occurs?

<p>The pH of the matrix increases.</p> Signup and view all the answers

Most CO2 from catabolism is released during ____.

<p>The citric acid cycle.</p> Signup and view all the answers

Which of the following statements about the chemiosmotic synthesis of ATP is correct?

<p>The chemiosmotic synthesis of ATP requires that the electron transport in the inner mitochondrial membrane be coupled to proton transport across the same membrane.</p> Signup and view all the answers

The molecule that functions as the reducing agent (electron donor) in a redox or oxidation-reduction reaction ____.

<p>Loses electrons and loses potential energy.</p> Signup and view all the answers

Which of the following statements describes the results of this reaction, C6H12O6 + 6 O2 → 6 CO2 + 6 H2O + Energy?

<p>C6H12O6 is oxidized and O2 is reduced.</p> Signup and view all the answers

When a glucose molecule loses a hydrogen atom as the result of an oxidation-reduction reaction, the molecule becomes ____.

<p>Oxidized.</p> Signup and view all the answers

Which of the following statements describes NAD+?

<p>NAD+ is reduced to NADH during glycolysis, pyruvate oxidation, and the citric acid cycle.</p> Signup and view all the answers

Where does glycolysis take place in eukaryotic cells?

<p>Cytosol.</p> Signup and view all the answers

The oxygen consumed during cellular respiration is involved directly in which process or event?

<p>Accepting electrons at the end of the electron transport chain.</p> Signup and view all the answers

Why are carbohydrates and fats considered high energy foods?

<p>They have a lot of electrons associated with hydrogen.</p> Signup and view all the answers

Which process in eukaryotic cells will proceed normally whether oxygen (O2) is present or absent?

<p>Glycolysis.</p> Signup and view all the answers

What is the term for metabolic pathways that release stored energy by breaking down complex molecules?

<p>Catabolic pathways.</p> Signup and view all the answers

A molecule that is phosphorylated ____.

<p>Has an increased chemical potential energy; it is primed to do cellular work.</p> Signup and view all the answers

Why is glycolysis described as having an investment phase and a payoff phase?

<p>It uses stored ATP and then forms a net increase in ATP.</p> Signup and view all the answers

For each molecule of glucose that is metabolized by glycolysis and the citric acid cycle, what is the total number of NADH + FADH2 molecules produced?

<p>12</p> Signup and view all the answers

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

<p>Oxidation of pyruvate to acetyl CoA and the citric acid cycle.</p> Signup and view all the answers

How many carbon atoms are fed into the citric acid cycle as a result of the oxidation of one molecule of pyruvate?

<p>Two</p> Signup and view all the answers

During cellular respiration, acetyl CoA accumulates in which location?

<p>Mitochondrial matrix.</p> Signup and view all the answers

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

<p>Mitochondrial intermembrane space.</p> Signup and view all the answers

What is proton-motive force?

<p>The force provided by a transmembrane hydrogen ion gradient.</p> Signup and view all the answers

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

<p>60-64</p> Signup and view all the answers

Where are the proteins of the electron transport chain located?

<p>Mitochondrial inner membrane.</p> Signup and view all the answers

Which of the following produces the most ATP when glucose (C6H12O6) is completely oxidized to carbon dioxide (CO2) and water?

<p>Oxidative phosphorylation (chemiosmosis).</p> Signup and view all the answers

Where is ATP synthase located in the mitochondrion?

<p>Inner membrane.</p> Signup and view all the answers

One function of both alcohol fermentation and lactic acid fermentation is to ____.

<p>Oxidize NADH to NAD+.</p> Signup and view all the answers

Which of the following normally occurs regardless of whether or not oxygen (O2) is present?

<p>Glycolysis.</p> Signup and view all the answers

Which metabolic pathway is common to both cellular respiration and fermentation?

<p>Glycolysis.</p> Signup and view all the answers

What is the purpose of beta oxidation in respiration?

<p>Breakdown of fatty acids.</p> Signup and view all the answers

Study Notes

Fermentation in Muscle Cells

  • Fermentation in muscle cells produces lactate and regenerates NAD+.
  • In anaerobic conditions, pyruvate is reduced while NADH is oxidized.
  • Under anaerobic conditions, the net gain of ATP per glucose molecule during glycolysis is two ATP.

Glycolysis Overview

  • Glycolysis is the initial stage of glucose oxidation and occurs in the cytosol.
  • It starts with ATP investment, using stored ATP to ultimately yield a net gain of two ATP molecules.
  • Two NADH are produced as part of the glycolysis process.
  • Major products of glycolysis include ATP and pyruvate, which can be used by other biological reactions.

Citric Acid Cycle (Krebs Cycle)

  • Acetyl CoA enters the citric acid cycle after the oxidation of pyruvate.
  • ATP production in the citric acid cycle occurs through substrate-level phosphorylation.
  • The last reaction of the cycle yields a substrate for the first reaction, indicating a cyclic nature.
  • Most CO2 produced during cellular respiration originates from the citric acid cycle.

Electron Transport Chain (ETC)

  • Electrons from glucose end up in water, with O2 acting as the final electron acceptor.
  • The electron transport chain is responsible for establishing a proton gradient in the mitochondrial intermembrane space.
  • ATP synthesis driven by the proton-motive force relies on the H+ concentration across the membrane holding ATP synthase.

Redox Reactions and ATP Production

  • NAD+ is reduced to NADH in glycolysis, pyruvate oxidation, and the citric acid cycle.
  • Fewer protons are pumped across the membrane when FADH2 is the electron donor compared to NADH, resulting in less ATP produced from FADH2.
  • In glycolysis and the citric acid cycle, carbon that does not end up as CO2 is used for building blocks in complex molecules.

Energy Flow and Efficiency

  • The complete oxidation of one glucose molecule can yield approximately 30-32 ATP, with oxidative phosphorylation accounting for the most ATP production.
  • Beta oxidation is a metabolic pathway that breaks down fatty acids for energy.
  • Both cellular respiration and fermentation share glycolysis as a common metabolic pathway.

Key Concepts of Cellular Respiration

  • Chemiosmosis is the coupling of electron transport with proton movement across a membrane for ATP synthesis.
  • ATP synthase is located in the mitochondrial inner membrane, where it utilizes the proton gradient to produce ATP.
  • Carbohydrates and fats are high-energy foods due to their high electron content associated with hydrogen.

Miscellaneous

  • The overall equation for glucose oxidation showcases glucose being oxidized and oxygen being reduced.
  • NADH is seen as an essential reducing agent in metabolic reactions, losing electrons and potential energy during redox processes.
  • Acetyl CoA accumulates in the mitochondrial matrix, serving as a significant metabolic intermediate.

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Description

Test your knowledge of key concepts in Campbell's biology textbook, specifically Chapter 9. This quiz covers important terms and definitions related to cellular processes and biochemical concepts. Perfect for students needing a refresher or preparation for exams.

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