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Campbell Biology, AP Edition9th EditionCain, Jackson, Minorsky, Reece, Urry, Wasserman 715 solutions 25. Apply your understanding of how living
organisms use energy to argue in favor of why it is either beneficial or detrimental for cells to use ATP rather than directly using the energy stored in the bonds of carbohydrates to power cellular reactions. ATP is readily available in the form of a single unit that provides a consistent, appropriate amount of energy. If cells harvested energy from various carbohydrate
compounds, they would need to tailor each reaction to each energy source. ATP energy cannot activate the ROS dependent stress response whereas food molecules are responsible for activating ROS. ATP is low in energy, but food molecules (in the form of carbohydrates) possess higher levels of energy that cells can use. ATP is readily available to cells, unlike the carbohydrate compounds that have to first be phosphorylated in order to release their energy. 26. What role does \text{NAD}^{+} {\!} play in redox reactions?
27. Which statement best explains how electrons are transferred and the role of each species. Remember that R represents a hydrocarbon molecule and RH represents the same molecule with a particular hydrogen identified. \text{RH} + \text{NAD}^{+} {\!} \rightarrow \text{NADH} + \text{R}
28. Nearly all organisms on Earth carry out some form of glycolysis. Provide an accurate argument that explains how this fact either supports or refutes the assertion that glycolysis is one of the oldest metabolic pathways.
29. Red blood cells (RBCs) do not perform aerobic respiration, but they do perform glycolysis. Provide the reasoning necessary to explain why all cells need an energy source, and predict what would happen if glycolysis were blocked in a sample of RBCs.
30. What is the primary difference between a circular pathway and a linear pathway?
31. Cellular respiration breaks down glucose and releases carbon dioxide and water. Which steps in the oxidation of pyruvate produces carbon dioxide?
32. What three steps are included in the breakdown of pyruvate?
33. Apply your understanding of the various components of the electron transport chain to evaluate how the roles of ubiquinone and cytochrome c differ from those of the other components.
34. Consider that the number of ATP molecules formed through cellular respiration varies. Identify the claim that accounts for these differences.
35. Which of the following best describes complex IV in the electron transport chain?
36. . Review the process of fermentation, as illustrated here by lactic acid fermentation. Which of the following statements best compares fermentation and anaerobic respiration and accurately highlights their differences?
37. What type of cellular respiration is represented in the following equation, and why? \text{CO}_2 + \text{H}_2 + \text{NADH} \rightarrow \text{CH}_4 + \text{H}_2\text{O} + \text{NAD}^+
38. Would you describe metabolic pathways as inherently wasteful or inherently economical? Justify your answer by explaining why you chose it.
39. Make a claim to identify the lipids that are connected to glucose catabolism pathways, and support your claim with evidence of how the lipids are connected to those pathways.
40. Examine and compare the statements below, each of which proposes the specific mechanism by which citrate from the citric acid cycle affects glycolysis. Which statement offers an accurate description of this effect?
41. Compare the two types of feedback mechanisms, as pictured. Make a claim to explain why negative feedback mechanisms might be more common than positive feedback mechanisms in living cells.
Is metabolic pathways inherently wasteful or inherently economical?Would you describe metabolic pathways as inherently wasteful or inherently economical, and why? They are very economical. The substrates, intermediates, and products move between pathways and do so in response to finely tuned feedback inhibition loops that keep metabolism balanced overall.
Would you describe metabolic pathways in the two energy processes wasteful or economical?Metabolic pathways are wasteful as they. perform uncoordinated catabolic and anabolic. reactions that wastes some of the energy that is. stored.
What makes metabolic pathways more efficient?Concentrating both substrates and enzymes in the same cellular location is one way to make metabolic pathways more efficient, as the products of one enzyme-catalyzed reaction become the reactants for the next reaction.
Why metabolic pathways are not considered closed systems?Metabolic pathways should be thought of as porous—that is, substances enter from other pathways, and other substances leave for other pathways. These pathways are not closed systems. Many of the products in a particular pathway are reactants in other pathways.
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