FINAL 07 2020, questions and answers PDF

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Module_5_ Ch_09...

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6/13/2020

Module #5: Ch 09

Module #5: Ch 09 Due: 11:59pm on Thursday, July 1, 2021 You will receive no credit for items you complete after the assignment is due. Grading Policy

Activity: Overview of Cellular Respiration

Click here to complete this activity. Then answer the questions.

Part A What process occurs in Box A?

ANSWER: glycolysis the citric acid cycle electron transport oxidative phosphorylation electron transport and oxidative phosphorylation

Correct Glycolysis occurs in the cytosol.

Part B

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Module #5: Ch 09

What process occurs within Box B?

ANSWER: electron transport the citric acid cycle glycolysis oxidative phosphorylation photophosphorylation

Correct The citric acid cycle transfers electrons to NADH and FADH2.

Part C What molecule is indicated by the letter D?

ANSWER: water oxygen pyruvate ATP glucose

Correct Oxygen is the final electron acceptor of cellular respiration.

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Module #5: Ch 09

Activity: Redox Reactions

Click here to view this animation. Then answer the questions.

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

Hint 1. Which is a property of atoms?

ANSWER: Electronegativity. Polarity. Oxidation. Reduction.

Correct Electronegativity is the tendency of an atom to attract electrons toward itself.

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

Hint 1. How does the electrical state of each atom change?

ANSWER: Anion and cation. Ionic and covalent. Proton and electron. Polar and nonpolar.

Correct Each atom will carry a charge from the transfer of electrons.

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

Hint 1. Consider the atomic properties of oxygen and hydrogen.

ANSWER: Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero. The electron in each hydrogen atom is completely transferred to the oxygen atom, and each hydrogen atom has a net charge of +1. Oxygen acts as the electron acceptor and is oxidized. There is equal sharing of the electrons between the oxygen atom and the two hydrogen atoms, and the net charge is zero.

Correct The oxygen and hydrogen atoms in water have partial charges, but the molecule has a net charge of zero.

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

Hint 1. What happens to the electrons and bonds during a redox reaction?

ANSWER: A hydrogen atom is transferred to the atom that loses an electron. The reactant that is oxidized loses electrons. The electron acceptor is reduced. Changes in potential energy can be released as heat.

Correct A hydrogen atom (proton, or H+) is often transferred to the atom that gains an electron.

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

Hint 1. Consider the electrons in the outermost shell of each atom.

ANSWER: Ionic. Redox. Nonpolar covalent. Polar covalent.

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Correct The complete transfer of an electron from lithium to fluorine results in a stable compound in which both atoms have full outermost shells.

Part F Gaseous hydrogen burns in the presence of oxygen to form water: 2H2 + O2 → 2H2 O + energy Which molecule is oxidized and what kind of bond is formed?

Hint 1. How are the electrons transferred?

ANSWER:

Hydrogen, nonpolar. Oxygen, polar. Hydrogen, polar. Oxygen, nonpolar.

Correct Hydrogen loses electrons to oxygen, which is more electronegative and thus pulls the electrons closer to itself in the water molecule.

Activity: Glycolysis

Click here to complete this activity. Then answer the questions.

Part A How many NADH are produced by glycolysis? ANSWER: 1 3 4 2 5

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Correct Two NADH molecules are produced by glycolysis.

Part B In glycolysis, ATP molecules are produced by _____. ANSWER:

photophosphorylation substrate-level phosphorylation cellular respiration oxidative phosphorylation photosynthesis

Correct A phosphate group is transferred from glyceraldehyde phosphate to ADP.

Part C Which of these is NOT a product of glycolysis? ANSWER: pyruvate FADH2 ATP NADH

Correct FADH2 is a product of the citric acid cycle.

Part D In glycolysis, what starts the process of glucose oxidation? ANSWER:

ATP ADP hexokinase FADH2 NADPH

Correct Some ATP energy is used to start the process of glucose oxidation.

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Module #5: Ch 09

In glycolysis there is a net gain of _____ ATP. ANSWER: 4 2 1 5 3

Correct It takes 2 ATP to produce 4 ATP.

Activity: Electron Transport

Click here to complete this activity. Then answer the questions.

Part A For each glucose that enters glycolysis, _____ acetyl CoA enter the citric acid cycle. ANSWER:

2 4 0 5 1

Correct Each glucose produces two pyruvates, each of which is converted into acetyl CoA.

Part B For each glucose that enters glycolysis, _____ NADH + H+ are produced by the citric acid cycle. ANSWER:

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Module #5: Ch 09 3 3 to 6 2 0 6

Correct 3 NADH + H+ are produced per each acetyl CoA that enters the citric acid cycle.

Part C In cellular respiration, most ATP molecules are produced by _____. ANSWER: photophosphorylation oxidative phosphorylation substrate-level phosphorylation photosynthesis cellular respiration

Correct This process utilizes energy released by electron transport.

Part D The final electron acceptor of cellular respiration is _____. ANSWER: FADH2 NADH water CO2 oxygen

Correct Oxygen is combined with electrons and hydrogen to form water.

Part E During electron transport, energy from _____ is used to pump hydrogen ions into the _____. ANSWER:

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Module #5: Ch 09 acetyl CoA ... intermembrane space NADH ... intermembrane space NADH ... mitochondrial matrix NADH and FADH2 ... mitochondrial matrix NADH and FADH2 ... intermembrane space

Correct The energy released as electrons, which have been donated by NADH and FADH2, is passed along the electron transport chain and used to pump hydrogen ions into the intermembrane space.

Part F Structure A is _____.

ANSWER:

phospholipid sensory protein an electron acceptor ATP synthase an electron donor

Correct ATP synthase phosphorylates ADP.

Part G The proximate (immediate) source of energy for oxidative phosphorylation is _____. ANSWER:

NADH and FADH2 ATP synthase kinetic energy that is released as hydrogen ions diffuse down their concentration gradient ATP substrate-level phosphorylation

Correct Concentration gradients are a form of potential energy.

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Module #5: Ch 09

Activity: Fermentation

Click here to complete this activity. Then answer the questions.

Part A In muscle cells, fermentation produces _____. ANSWER:

lactate, NADH, and ATP pyruvate carbon dioxide, ethanol, and NAD+ carbon dioxide, ethanol, NADH, and ATP lactate and NAD+

Correct These are the products of fermentation as it occurs in muscle cells.

Part B In fermentation _____ is reduced and _____ is oxidized. ANSWER: pyruvate ... NADH lactate ... NADH NAD+ ... pyruvate NADH ... lactate lactate ... ethanol

Correct The pyruvate from glycolysis is reduced to either lactate or ethanol, and NADH is oxidized to NAD+.

Activity: The Citric Acid Cycle

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Module #5: Ch 09

Click here to complete this activity. Then answer the questions.

Part A Which of these enters the citric acid cycle? ANSWER:

pyruvate NADH + H+ acetyl CoA G3P glucose

Correct Acetyl CoA is a reactant in the citric acid cycle.

Part B In the citric acid cycle, ATP molecules are produced by _____. ANSWER: photophosphorylation oxidative phosphorylation photosynthesis substrate-level phosphorylation cellular respiration

Correct A phosphate group is transferred from GTP to ADP.

Part C Which of these is NOT a product of the citric acid cycle? ANSWER:

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Module #5: Ch 09 FADH2 ATP acetyl CoA CO2 NADH + H+

Correct Acetyl CoA enters the citric acid cycle.

Cellular Respiration (4 of 5): Oxidative Phosphorylation (BioFlix tutorial) Oxidative phosphorylation consists of two tightly linked processes - electron transport and ATP synthesis. In electron transport, the NADH and FADH2 produced in the first three stages of cellular respiration are oxidized by O2 (the oxidative part of this stage). These redox reactions also drive the pumping of protons across the inner mitochondrial membrane, creating a proton ( H+) gradient. This H+ gradient is used to power the chemiosmotic synthesis of ATP from ADP and Pi (the phosphorylation part of this stage). As you watch the Oxidative Phosphorylation animation, pay close attention to how electron transport is coupled to the formation of the H+ gradient and ATP synthesis.

Part A - The role of O2 in electron transport In mitochondrial electron transport, what is the direct role of O2?

Hint 1. The definition of “direct role” A molecule plays a direct role in a chemical reaction if it participates in the reaction as either a reactant or a product, or if it is part of the catalytic machinery (enzymes or cofactors) that allows the reaction to occur. Hint 2. The electron transport chain The electron transport chain (shown in this diagram) consists of a sequence of electron carriers, most of which are components of the four main protein complexes (I - IV) embedded in the inner mitochondrial membrane. Two other substances, Q and Cyt c, are mobile carriers that shuttle electrons between the protein complexes. Note the different locations where electrons from NADH and FADH2 enter the electron transport chain and the role that O2 plays in this process.

ANSWER:

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Module #5: Ch 09 to provide the driving force for the production of a proton gradient to function as the final electron acceptor in the electron transport chain to oxidize NADH and FADH2 from glycolysis, acetyl CoA formation, and the citric acid cycle to provide the driving force for the synthesis of ATP from ADP and Pi

Correct The only place that O2 participates in cellular respiration is at the end of the electron transport chain, as the final electron acceptor. Oxygen's high affinity for electrons ensures its success in this role. Its contributions to driving electron transport, forming a proton gradient, and synthesizing ATP are all indirect effects of its role as the terminal electron acceptor.

Part B - The effects of anaerobic conditions How would anaerobic conditions (when no O2 is present) affect the rate of electron transport and ATP production during oxidative phosphorylation? (Note that you should not consider the effect on ATP synthesis in glycolysis or the citric acid cycle.)

Hint 1. The role of O2 in electron transport O2 is the final electron acceptor in the electron transport chain. Without O2, there is no place for the electrons from NADH and FADH2 (and ultimately from glucose) to go. Hint 2. What is the link between electron transport and ATP synthesis in oxidative phosphorylation? If electron transport stops because there is no O2 to serve as the final electron acceptor, ATP synthesis associated with oxidative phosphorylation also stops. Why? ANSWER: ATP synthesis in oxidative phosphorylation is directly driven by electrons moving from NADH and FADH2 to O2. Without electron transport, the inner mitochondrial membrane becomes leaky to protons and the proton gradient rapidly dissipates. The synthesis of ATP from ADP and Pi creates a proton gradient across the inner mitochondrial membrane. This gradient is required for NADH oxidation by O2. Without electron transport from NADH and FADH2 to O2, the pumping of protons across the inner mitochondrial membrane ceases.

ANSWER:

Both electron transport and ATP synthesis would stop. Electron transport would stop but ATP synthesis would be unaffected. Neither electron transport nor ATP synthesis would be affected. Electron transport would be unaffected but ATP synthesis would stop.

Correct Oxygen plays an essential role in cellular respiration because it is the final electron acceptor for the entire process. Without O2, mitochondria are unable to oxidize the NADH and FADH2 produced in the first three steps of cellular respiration, and thus cannot make any ATP via oxidative phosphorylation. In addition, without O2 the mitochondria cannot oxidize the NADH and FADH2 back to NAD+ and FAD, which are needed as inputs to the first three stages of cellular respiration.

Part C - Comparing the amount of ATP synthesis from NADH and FADH2 NADH and FADH2 are both electron carriers that donate their electrons to the electron transport chain. The electrons ultimately reduce O2 to water in the final step of electron transport. However, the amount of ATP made by electrons from an NADH molecule is greater than the amount made by electrons

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Module #5: Ch 09

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

Hint 1. How does the number of protons pumped across the membrane per NADH and FADH2 compare? Once an H+ ion is pumped across the inner mitochondrial membrane and becomes part of the H+ gradient, it has the potential to drive the same amount of ATP synthesis as any other H+ ion, regardless of where it was pumped across the membrane. Thus, an H+ ion derived from the oxidation of NADH is equivalent to an H+ ion derived from the oxidation of FADH2. Because more ATP is made from an NADH molecule than from an FADH2 molecule, what must be true about the number of H+ ions that these two molecules contribute to the H+ gradient? ANSWER:

NADH contributes more H+ ions than FADH2. Both NADH and FADH2 contribute the same number of H+ ions . NADH contributes fewer H+ ions than FADH2.

Hint 2. NADH and FADH2 donate electrons at different positions along the electron transport chain Although NADH and FADH2 have very similar functions in cellular respiration (they are both reduced electron carriers), they donate their electrons at different points along the electron transport chain.

ANSWER: FADH2 is made only in the citric acid cycle while NADH is made in glycolysis, acetyl CoA formation, and the citric acid cycle. It takes more energy to make ATP from ADP and Pi using FADH2 than using NADH. Fewer protons are pumped across the inner mitochondrial membrane when FADH2 is the electron donor than when NADH is the electron donor. There is more NADH than FADH2 made for every glucose that enters cellular respiration. The H+ gradient made from electron transport using NADH is located in a different part of the mitochondrion than the H+ gradient made using FADH2.

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Module #5: Ch 09

Correct Electrons derived from the oxidation of FADH2 enter the electron transport chain at Complex II, farther down the chain than electrons from NADH (which enter at Complex I). This results in fewer H+ ions being pumped across the membrane for FADH2 compared to NADH, as this diagram shows. Thus, more ATP can be produced per NADH than FADH2.

Part D - The effect of gramicidin on oxidative phosphorylation When the protein gramicidin is integrated into a membrane, an H+ channel forms and the membrane becomes very permeable to protons (H+ ions). If gramicidin is added to an actively respiring muscle cell, how would it affect the rates of electron transport, proton pumping, and ATP synthesis in oxidative phosphorylation? (Assume that gramicidin does not affect the production of NADH and FADH2 during the early stages of cellular respiration.) Sort the labels into the correct bin according to the effect that gramicidin would have on each process.

Hint 1. Review the Oxidative Phosphorylation animation In oxidative phosphorylation, electron transport is coupled to the synthesis of ATP via a proton gradient that forms across the inner mitochondrial membrane. In the Oxidative Phosphorylation animation, watch how the proton gradient is created by electron transport and how it is used in the synthesis of ATP.

Hint 2. How to approach the problem You know that membranes treated with gramicidin become very leaky to protons. Consider these four questions (in this order) to help you evaluate how gramicidin alters oxidative phosphorylation. 1. Is a proton gradient across the inner mitochondrial membrane required for ATP synthesis during oxidative phosphorylation? 2. What effect does a membrane that is very leaky to protons have on the ability of the mitochondrion to maintain a proton gradient across that membrane? 3. What effect does the ability of the mitochondrion to maintain a proton gradient have on the rate of proton pumping? 4. How is the rate of electron transport related to the rate of proton pumping, and are these rates affected by the membrane being leaky to protons? Hint 3. How would gramicidin affect electron transport and proton pumping?

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Module #5: Ch 09

Think about how gramicidin would affect proton pumping driven by electron transport. Which of the following statements is correct? ANSWER: Gramicidin would prevent electron transport from pum...