Chpt 3 Anaerobic Metabolism Flashcards
- Question: Which of the following is NOT a major source of energy for cells? Options: a) Carbohydrates b) Lipids c) Proteins d) Vitamins
Answer: d) Vitamins Explanation: Vitamins are essential organic compounds but they are not a major source of energy. Carbohydrates lipids and proteins are all macronutrients that can be broken down to produce ATP the cell’s primary energy currency.
- Question: Approximately what percentage of energy from glucose is released during glycolysis? Options: a) 7% b) 10% c) 50% d) 93%
Answer: a) 7% Explanation: Glycolysis only extracts a small portion of the total energy stored in glucose. The majority of energy is released during oxidative phosphorylation (in aerobic respiration).
- Question: Where in the cell do anaerobic processes like glycolysis and fermentation take place? Options: a) Nucleus b) Mitochondria c) Cytoplasm d) Golgi apparatus
Answer: c) Cytoplasm Explanation: Glycolysis and fermentation are anaerobic processes that occur in the cytoplasm of the cell not requiring the mitochondria.
- Question: Which of the following is NOT an activated carrier involved in anaerobic metabolism? Options: a) ATP b) NADH c) Acetyl CoA d) FADH2
Answer: c) Acetyl CoAExplanation: Acetyl CoA is an activated carrier involved in aerobic respiration (specifically the citric acid cycle) not anaerobic metabolism. ATP and NADH are crucial in both aerobic and anaerobic processes while FADH2 plays a role in aerobic respiration.
- Question: What is the ultimate electron acceptor in aerobic respiration? Options: a) Water b) Carbon dioxide c) Oxygen d) Pyruvate
Answer: c) OxygenExplanation: In aerobic respiration oxygen acts as the final electron acceptor in the electron transport chain.
- Question: What is the main product of the first stage of cellular respiration? Options: a) Glucose b) Pyruvate c) Acetyl CoA d) ATP
Answer: b) PyruvateExplanation: The first stage of cellular respiration is glycolysis which produces pyruvate.
- Question: In which stage of cellular respiration is carbon dioxide (CO2) released? Options: a) First stage b) Second stage c) Third stage d) All stages
Answer: b) Second stageExplanation: Carbon dioxide is released during the citric acid cycle (the second stage of cellular respiration).
- Question: The glycolytic pathway is a series of how many reactions? Options: a) 5 b) 8 c) 10 d) 12
Answer: c) 10Explanation: The glycolytic pathway consists of ten enzyme-catalyzed reactions.
- Question: Who is credited with discovering the glycolytic pathway? Options: a) Hans Krebs b) Gustav Embden c) Otto Meyerhof d) Both b and c
Answer: d) Both b and c Explanation: Gustav Embden and Otto Meyerhof are both credited with significant contributions to the discovery and elucidation of the glycolytic pathway.
- Question: What are the two phases of glycolysis? Options: a) Preparatory and payoff b) Oxidation and reduction c) Anaerobic and aerobic d) Citric acid cycle and electron transport chain
Answer: a) Preparatory and payoffExplanation: Glycolysis is divided into two phases: the preparatory phase (energy investment) and the payoff phase (energy generation).
- Question: How many ATP molecules are used in the preparatory phase of glycolysis? Options: a) 0 b) 1 c) 2 d) 4
Answer: c) 2 Explanation: Two ATP molecules are consumed in the preparatory phase of glycolysis to phosphorylate glucose and fructose-6-phosphate.
- Question: How many ATP molecules are produced in the payoff phase of glycolysis? Options: a) 2 b) 4 c) 6 d) 8
Answer: b) 4 Explanation: Four ATP molecules are produced in the payoff phase of glycolysis through substrate-level phosphorylation.
- Question: What is the fate of pyruvate in the yeast cell under anaerobic conditions? Options: a) Lactic acid b) Ethanol c) Acetyl CoA d) Glucose
Answer: b) Ethanol Explanation: In yeast under anaerobic conditions pyruvate is converted to ethanol through alcoholic fermentation.
- Question: How many molecules of NADH are produced per glucose molecule during glycolysis? Options: a) 1 b) 2 c) 3 d) 4
Answer: b) 2 Explanation: Two molecules of NADH are produced per glucose molecule during glycolysis (one per glyceraldehyde-3-phosphate molecule).
- Question: Which enzyme catalyzes the conversion of pyruvate to acetyl-CoA? Options: a) Hexokinase b) Phosphofructokinase c) Pyruvate dehydrogenase d) Lactate dehydrogenase
Answer: c) Pyruvate dehydrogenase Explanation: Pyruvate dehydrogenase is the enzyme complex that catalyzes the conversion of pyruvate to acetyl-CoA in the link reaction before the citric acid cycle.
- Question: What are the two types of fermentation discussed in the text? Options: a) Alcoholic and lactic acid b) Aerobic and anaerobic c) Homolactic and heterolactic d) Ethanol and lactate
Answer: a) Alcoholic and lactic acid Explanation: These are the two main types of fermentation discussed in relation to anaerobic metabolism.
- Question: What is the product of alcoholic fermentation? Options: a) Lactate b) Ethanol and CO2 c) Acetyl CoA d) Glucose
Answer: b) Ethanol and CO2 Explanation: Alcoholic fermentation produces ethanol and carbon dioxide as byproducts.
- Question: Which coenzyme is required for the decarboxylation of pyruvate to acetaldehyde in alcoholic fermentation? Options: a) NADH b) FADH2 c) Thiamine pyrophosphate d) Coenzyme A
Answer: c) Thiamine pyrophosphate Explanation: Thiamine pyrophosphate (TPP) is a coenzyme required by pyruvate decarboxylase for the decarboxylation of pyruvate.
- Question: What is regenerated in the second reaction of alcoholic fermentation? Options: a) Pyruvate b) Acetaldehyde c) Ethanol d) NAD+
Answer: d) NAD+ Explanation: The second reaction of alcoholic fermentation (aldehyde reductase) regenerates NAD+ from NADH allowing glycolysis to continue.
- Question: Where does homolactic fermentation occur? Options: a) Yeast cells b) Lactic acid bacteria and skeletal muscle c) Mitochondria d) Cytoplasm of all cells
Answer: b) Lactic acid bacteria and skeletal muscle Explanation: Homolactic fermentation occurs in lactic acid bacteria and also in vertebrate skeletal muscle cells during strenuous exercise.
- Question: What is the product of homolactic fermentation? Options: a) Ethanol b) Lactate c) Acetyl CoA d) CO2
Answer: b) Lactate Explanation: Homolactic fermentation produces only lactate as a product.
- Question: What is the standard free energy change (ΔG°’) for lactic acid fermentation? Options: a) +25.1 kJ/mol b) -25.1 kJ/mol c) 0 kJ/mol d) +3.5 kJ/mol
Answer: b) -25.1 kJ/mol Explanation: Lactic acid fermentation is an exergonic process with a negative standard free energy change.
- Question: Where is the NADH produced in homolactic fermentation useful? Options: a) Glycolysis b) Oxidative phosphorylation in the mitochondrial electron transport chain c) Citric acid cycle d) Gluconeogenesis
Answer: a) Glycolysis Explanation: In homolactic fermentation the NADH produced in glycolysis is used to reduce pyruvate to lactate regenerating NAD+ for continued glycolysis.
- Question: Which of the following reactions in glycolysis are irreversible? Options: a) All reactions b) Some reactions c) None of the reactions d) Only the reactions in the payoff phase
Answer: b) Some reactionsExplanation: The reactions catalyzed by hexokinase phosphofructokinase-1 and pyruvate kinase are irreversible under standard cellular conditions.