Exergonic vs endergonic reactions

Which term describes the degree to which an element attracts electrons? View Available Hint(s) Which term describes the degree to which an element attracts electrons? Electronegativity. Polarity. Reduction. Oxidation. SubmitPrevious Answers  Correct Electronegativity is the tendency of an atom to attract electrons toward itself. Part B Part complete Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other? View Available Hint(s) Which terms describe two atoms when they form a bond in which electrons are completely transferred from one atom to the other? Proton and electron. Ionic and covalent. Polar and nonpolar. Anion and cation. SubmitPrevious Answers  Correct Each atom will carry a charge from the transfer of electrons. Part C Part complete Which of the following statements is true of the bonds in a water molecule? View Available Hint(s) Which of the following statements is true of the bonds in a water molecule? Oxygen holds electrons more tightly than hydrogen does, and the net charge is zero. Oxygen acts as the electron acceptor and is oxidized. The electron in each hydrogen atom is completely transferred to the oxygen atom, and each hydrogen atom has a net charge of +1. There is equal sharing of the electrons between the oxygen atom and the two hydrogen atoms, and the net charge is zero. SubmitPrevious Answers  Correct The oxygen and hydrogen atoms in water have partial charges, but the molecule has a net charge of zero. Part D Part complete Which of the following statements is not true of most cellular redox reactions? View Available Hint(s) Which of the following statements is not true of most cellular redox reactions? The reactant that is oxidized loses electrons. A hydrogen atom is transferred to the atom that loses an electron. The electron acceptor is reduced. Changes in potential energy can be released as heat. SubmitPrevious Answers  Correct A hydrogen atom (proton, or H+) is often transferred to the atom that gains an electron. Part E Part complete What kind of bond is formed when lithium and fluorine combine to form lithium fluoride? View Available Hint(s) What kind of bond is formed when lithium and fluorine combine to form lithium fluoride? Redox. Nonpolar covalent. Polar covalent. Ionic. SubmitPrevious Answers  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 Part complete 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? View Available Hint(s) 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? Hydrogen, polar. Oxygen, nonpolar. Hydrogen, nonpolar. Oxygen, polar. SubmitPrevious Answers  Correct Hydrogen loses electrons to oxygen, which is more electronegative and thus pulls the electrons closer to itself in the water molecule. Part complete Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions? View Available Hint(s) Among the products of glycolysis, which compounds contain energy that can be used by other biological reactions? CO2 only pyruvate, ATP, and NADH NADH only O2 only pyruvate and ATP only ATP only ATP and NADH only More ATP is produced per CO2 released in cyclic processes than in linear processes. 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. Redox reactions that simultaneously produce CO2 and NADH occur only in cyclic processes. Cyclic processes, such as the citric acid cycle, require a different mechanism of ATP synthesis than linear processes, such as glycolysis. SubmitPrevious Answers  Correct Although it is possible to oxidize the two-carbon acetyl group of acetyl CoA to two molecules of CO2, it is much more difficult than adding the acetyl group to a four-carbon acid to form a six-carbon acid (citrate). Citrate can then be oxidized sequentially to release two molecules of CO2. In mitochondrial electron transport, what is the direct role of O2? View Available Hint(s) In mitochondrial electron transport, what is the direct role of O2? to provide the driving force for the synthesis of ATP from ADP and Pi 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 SubmitPrevious Answers  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 Part complete 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.) View Available Hint(s) 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.) Neither electron transport nor ATP synthesis would be affected. Electron transport would stop but ATP synthesis would be unaffected. Both electron transport and ATP synthesis would stop. Electron transport would be unaffected but ATP synthesis would stop. SubmitPrevious Answers  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 Part complete 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 from an FADH2 molecule. Which statement best explains why more ATP is made per molecule of NADH than per molecule of FADH2? View Available Hint(s) Which statement best explains why more ATP is made per molecule of NADH than per molecule of FADH2? 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. 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. SubmitPrevious Answers  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. In muscle cells, fermentation produces _____. In muscle cells, fermentation produces _____. carbon dioxide, ethanol, NADH, and ATP lactate, NADH, and ATP carbon dioxide, ethanol, and NAD+ pyruvate lactate and NAD+ SubmitPrevious Answers  Correct These are the products of fermentation as it occurs in muscle cells. Part B Part complete In fermentation _____ is reduced and _____ is oxidized. In fermentation _____ is reduced and _____ is oxidized. NADH ... lactate NAD+ ... pyruvate lactate ... NADH lactate ... ethanol pyruvate ... NADH SubmitPrevious Answers  Correct The pyruvate from glycolysis is reduced to either lactate or ethanol, and NADH is oxidized to NAD+.