NCERT - RESPIRATION IN PLANTS - 24-25
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Questions and Answers

What is the role of cytochrome c in the electron transport chain?

  • It synthesizes ATP from ADP and inorganic phosphate.
  • It acts as a mobile carrier for electron transfer. (correct)
  • It contains copper centers that facilitate oxidation.
  • It reduces ubiquinone to form ubiquinol.

    • What does complex IV in the electron transport chain consist of?

  • Ubiquinone and other electron carriers.
  • NADH and FADH2.
  • Cytochromes a and a3, and two copper centers. (correct)
  • ATP synthase and ADP.

    • How many molecules of ATP are produced from the oxidation of one molecule of NADH?

  • 4
  • 3 (correct)
  • 1
  • 2

    • What is the primary function of complex V in the electron transport chain?

    <p>To couple electron transport with ATP synthesis. (A)</p> Signup and view all the answers

    What determines the number of ATP molecules synthesized during respiration?

    <p>The nature of the electron donor. (D)</p> Signup and view all the answers

    What is the limiting factor for the aerobic process of respiration?

    <p>The availability of oxygen. (C)</p> Signup and view all the answers

    What is the function of cytochrome b c1 complex (complex III)?

    <p>To transfer electrons to cytochrome c. (D)</p> Signup and view all the answers

    What is the main outcome of the electron transport chain?

    <p>Synthesis of ATP from ADP and inorganic phosphate. (B)</p> Signup and view all the answers

    What is one of the main conditions under which fermentation occurs?

    <p>Anaerobic conditions (B)</p> Signup and view all the answers

    Which enzyme is involved in converting pyruvic acid to ethanol during alcoholic fermentation?

    <p>Pyruvic acid decarboxylase (B), Alcohol dehydrogenase (D)</p> Signup and view all the answers

    What is produced as a byproduct of lactic acid fermentation in animal muscles during exercise?

    <p>Lactic acid (D)</p> Signup and view all the answers

    What percentage of energy from glucose is typically released during fermentation processes?

    <p>Less than 7 percent (B)</p> Signup and view all the answers

    What is the main advantage of aerobic respiration compared to fermentation?

    <p>It generates a higher yield of ATP (B)</p> Signup and view all the answers

    Which of the following processes occurs in mitochondria and requires oxygen?

    <p>Krebs' cycle (A)</p> Signup and view all the answers

    How do yeasts become inhibited by high concentrations of alcohol during fermentation?

    <p>Alcohol concentration reaches toxic levels (C)</p> Signup and view all the answers

    What reducing agent is reoxidized to NAD+ during the fermentation processes?

    <p>NADH+H+ (C)</p> Signup and view all the answers

    What is the primary purpose of cellular respiration in cells?

    <p>To break down food materials to release energy (A)</p> Signup and view all the answers

    Where does the breakdown of complex molecules primarily occur in eukaryotic cells?

    <p>In the cytoplasm and mitochondria (C)</p> Signup and view all the answers

    What are respiratory substrates primarily used for during cellular respiration?

    <p>Oxidation to release energy for ATP synthesis (A)</p> Signup and view all the answers

    What role does ATP play in cells?

    <p>It serves as the energy currency of the cell (B)</p> Signup and view all the answers

    How do plants primarily ensure the uptake of oxygen for respiration?

    <p>By using stomata and lenticels (C)</p> Signup and view all the answers

    Why can plant parts manage gas exchange without specialized organs?

    <p>Because each part manages its own gas exchange needs (C)</p> Signup and view all the answers

    What is a key difference in respiration rates between plants and animals?

    <p>Plants have lower respiration rates compared to animals (C)</p> Signup and view all the answers

    During cellular respiration, what happens to the energy released from respiratory substrates?

    <p>It is captured in a series of enzymatic steps as ATP (B)</p> Signup and view all the answers

    What is formed when citrate is isomerised?

    <p>Isocitrate (C)</p> Signup and view all the answers

    Which molecule is produced during the conversion of succinyl-CoA to succinic acid?

    <p>GTP (D)</p> Signup and view all the answers

    What is the primary function of NAD+ in the citric acid cycle?

    <p>Reducing to NADH + H+ (C)</p> Signup and view all the answers

    What is the outcome when GTP is converted to GDP?

    <p>Synthesis of ATP from ADP (D)</p> Signup and view all the answers

    Which compound acts as a substrate level phosphorylating agent in the cycle?

    <p>Succinyl-CoA (A)</p> Signup and view all the answers

    Which of the following steps involves the oxidation of FAD?

    <p>Oxidation of succinate to fumarate (B)</p> Signup and view all the answers

    What is the role of oxaloacetic acid in the citric acid cycle?

    <p>Acts as a starting and replenishing material for the cycle (C)</p> Signup and view all the answers

    How many points in the citric acid cycle reduce NAD+ to NADH + H+?

    <p>Three (B)</p> Signup and view all the answers

    What is the net gain of ATP molecules during the aerobic respiration of one molecule of glucose?

    <p>38 ATP (A)</p> Signup and view all the answers

    How does fermentation compare to aerobic respiration in terms of glucose breakdown?

    <p>Fermentation accounts for partial breakdown of glucose. (C)</p> Signup and view all the answers

    Which substrates are primarily converted into glucose before being used for respiration?

    <p>Carbohydrates (C)</p> Signup and view all the answers

    What is required for fatty acids before they can enter the respiratory pathway?

    <p>They must be degraded to acetyl CoA. (C)</p> Signup and view all the answers

    What is the primary role of NADH in fermentation compared to aerobic respiration?

    <p>NADH is oxidized to NAD+ slowly in fermentation. (A)</p> Signup and view all the answers

    Why has the respiratory process traditionally been considered a catabolic process?

    <p>It involves the breakdown of substrates. (C)</p> Signup and view all the answers

    At which stage do amino acids enter the respiratory pathway after degradation?

    <p>Krebs’ cycle or as pyruvate. (C)</p> Signup and view all the answers

    What happens to the compounds used for energy during respiration in relation to substrate synthesis?

    <p>They are withdrawn for the synthesis of substrates. (B)</p> Signup and view all the answers

    Which substrate is favored for cellular respiration in living organisms?

    <p>Glucose (C)</p> Signup and view all the answers

    Where does glycolysis occur within a cell?

    <p>Cytoplasm (C)</p> Signup and view all the answers

    What is the ultimate electron acceptor in aerobic respiration?

    <p>Oxygen (C)</p> Signup and view all the answers

    What occurs under anaerobic conditions during cellular respiration?

    <p>Lactic acid fermentation (D)</p> Signup and view all the answers

    Which of the following processes generates the most energy during respiration?

    <p>Electron transport chain (A)</p> Signup and view all the answers

    What does the respiratory quotient indicate?

    <p>Type of respiratory substrate used (A)</p> Signup and view all the answers

    Which statement best describes the Krebs cycle?

    <p>It is part of aerobic respiration that generates NADH and FADH2. (A)</p> Signup and view all the answers

    In what part of the mitochondria does oxidative phosphorylation occur?

    <p>Inner membrane (B)</p> Signup and view all the answers

    What process allows plants to trap light energy and convert it into chemical energy?

    <p>Photosynthesis (A)</p> Signup and view all the answers

    Which part of the plant typically carries out photosynthesis?

    <p>Cells containing chloroplasts (D)</p> Signup and view all the answers

    What is the primary source of energy for all life processes in plants?

    <p>Oxidation of food (D)</p> Signup and view all the answers

    What are saprophytes like fungi primarily dependent on for their energy needs?

    <p>Dead and decaying matter (C)</p> Signup and view all the answers

    Which organisms can prepare their own food through photosynthesis?

    <p>Green plants and cyanobacteria (A)</p> Signup and view all the answers

    What must occur for food to be used by non-green parts of a plant?

    <p>Food has to be translocated from green parts (A)</p> Signup and view all the answers

    How do animals obtain their food?

    <p>They directly consume plants or other animals (A)</p> Signup and view all the answers

    Where does the energy released during respiration ultimately come from?

    <p>Photosynthesis in green plants (A)</p> Signup and view all the answers

    Which of the following complexes is responsible for the oxidation of ubiquinol?

    <p>Complex III (A)</p> Signup and view all the answers

    How many ATP molecules are produced from the oxidation of one molecule of FADH2?

    <p>2 (C)</p> Signup and view all the answers

    What role does oxygen play in the electron transport chain?

    <p>It serves as the terminal electron acceptor. (B)</p> Signup and view all the answers

    Which statement describes the relationship between the electron transport chain and ATP production?

    <p>The electron transfer is directly coupled to ATP synthesis. (A)</p> Signup and view all the answers

    What factor influences the number of ATP molecules synthesized during aerobic respiration?

    <p>The type of respiratory substrate used. (D)</p> Signup and view all the answers

    Which electron carrier is involved in transferring electrons between complex III and IV?

    <p>Cytochrome c (D)</p> Signup and view all the answers

    What is the primary substrate used for respiration in living organisms?

    <p>Glucose (A)</p> Signup and view all the answers

    During glycolysis, how many molecules of pyruvic acid are generated from one molecule of glucose?

    <p>2 (B)</p> Signup and view all the answers

    Which process occurs in the mitochondria and is dependent on the presence of oxygen?

    <p>Aerobic respiration (B)</p> Signup and view all the answers

    What is the role of the electron transport system in cellular respiration?

    <p>To trap energy and synthesize ATP (D)</p> Signup and view all the answers

    What happens to pyruvic acid under anaerobic conditions?

    <p>It undergoes fermentation (D)</p> Signup and view all the answers

    Which molecules are generated during the Krebs cycle?

    <p>NADH + H+ and FADH2 (C)</p> Signup and view all the answers

    In the context of cellular respiration, what does the term 'amphibolic pathway' refer to?

    <p>A pathway involving both anabolism and catabolism (A)</p> Signup and view all the answers

    What primary process allows cells to partially oxidise glucose without oxygen?

    <p>Glycolysis (A)</p> Signup and view all the answers

    In which part of a plant does photosynthesis predominantly occur?

    <p>Leaves (C)</p> Signup and view all the answers

    What is the end product of the complete combustion of glucose?

    <p>Carbon dioxide and energy (C)</p> Signup and view all the answers

    What is a major advantage of oxidizing glucose in several steps during respiration?

    <p>It minimizes heat loss and maximizes ATP production. (C)</p> Signup and view all the answers

    What term describes organisms that can live in both aerobic and anaerobic conditions?

    <p>Facultative anaerobes (B)</p> Signup and view all the answers

    What structures in plant stems facilitate gas exchange?

    <p>Lenticels (C)</p> Signup and view all the answers

    What is the initial step of glycolysis?

    <p>Conversion of glucose to glucose-6-phosphate (C)</p> Signup and view all the answers

    Which atmosphere likely hosted the first cells on Earth?

    <p>Lacking oxygen (A)</p> Signup and view all the answers

    What makes the respiratory pathway considered amphibolic?

    <p>It simultaneously participates in both anabolism and catabolism. (D)</p> Signup and view all the answers

    What is the respiratory quotient (RQ) when carbohydrates are used as a substrate?

    <p>1.0 (A)</p> Signup and view all the answers

    What is the RQ value associated with the use of fats during respiration?

    <p>0.7 (D)</p> Signup and view all the answers

    What happens to acetyl CoA during the synthesis of fatty acids?

    <p>It is withdrawn from the respiratory pathway. (B)</p> Signup and view all the answers

    What does an RQ value of 0.9 suggest about the type of substrate being used?

    <p>Proteins are primarily used as substrates. (C)</p> Signup and view all the answers

    How is catabolism defined in the context of metabolism?

    <p>It describes breakdown processes that release energy. (C)</p> Signup and view all the answers

    Which statement is true regarding the respiratory quotient?

    <p>RQ values can indicate metabolic activity. (C)</p> Signup and view all the answers

    What is the main outcome of the respiratory pathway?

    <p>Release of CO2 and energy. (B)</p> Signup and view all the answers

    How many ATP molecules are synthesised during glycolysis from one glucose molecule?

    <p>2 (C)</p> Signup and view all the answers

    Which substance is formed when PGAL is converted into 1,3-bisphosphoglycerate?

    <p>NADH + H+ (D)</p> Signup and view all the answers

    What occurs during the conversion of 3-phosphoglyceraldehyde to 1,3-bisphosphoglycerate?

    <p>Two hydrogen atoms are removed. (A)</p> Signup and view all the answers

    What is the final product of glycolysis?

    <p>Pyruvic acid (A)</p> Signup and view all the answers

    Which of the following statements about ATP synthesis in glycolysis is true?

    <p>ATP is produced exclusively from substrate-level phosphorylation. (D)</p> Signup and view all the answers

    What is the role of ATP during the initial stages of glycolysis?

    <p>ATP is hydrolyzed to ADP. (C)</p> Signup and view all the answers

    What type of reaction occurs when fructose 1,6-bisphosphate is converted into dihydroxyacetone phosphate and 3-phosphoglyceraldehyde?

    <p>Isomerization (C)</p> Signup and view all the answers

    During glycolysis, how is energy primarily captured during the conversion of 1,3-bisphosphoglycerate to 3-phosphoglyceric acid?

    <p>By synthesizing ATP (C)</p> Signup and view all the answers

    What is the primary source of energy for plants?

    <p>Photosynthesis (D)</p> Signup and view all the answers

    Which part of the plant primarily carries out photosynthesis?

    <p>Leaves (A)</p> Signup and view all the answers

    How do non-green parts of the plant obtain the necessary food?

    <p>Translocating food from green parts (A)</p> Signup and view all the answers

    What is the process by which green plants capture light energy?

    <p>Photosynthesis (A)</p> Signup and view all the answers

    What type of nutrition do animals primarily exhibit?

    <p>Heterotrophic (B)</p> Signup and view all the answers

    What do green plants predominantly use to produce energy for life processes?

    <p>Macromolecule oxidation (D)</p> Signup and view all the answers

    Which organisms are capable of preparing their own food through photosynthesis?

    <p>Green plants and cyanobacteria (A)</p> Signup and view all the answers

    Which of the following is true about the relationship between respiration and energy?

    <p>Energy is released from food during respiration. (A)</p> Signup and view all the answers

    How does glucose utilization in fermentation compare to aerobic respiration?

    <p>Glucose is partially broken down in fermentation. (C)</p> Signup and view all the answers

    What must fatty acids undergo before they can enter the respiratory pathway?

    <p>Conversion into acetyl CoA (C)</p> Signup and view all the answers

    What is a characteristic of NADH oxidation in fermentation compared to aerobic respiration?

    <p>It is less vigorous in fermentation. (C)</p> Signup and view all the answers

    What is the primary reason respiration has been traditionally viewed as a catabolic process?

    <p>It generates ATP from glucose breakdown. (B)</p> Signup and view all the answers

    Which type of pathways work simultaneously in a living system rather than sequentially?

    <p>Both anabolic and catabolic pathways (B)</p> Signup and view all the answers

    At what point can amino acids enter the respiratory pathway after degradation?

    <p>During the Krebs cycle (A)</p> Signup and view all the answers

    What is one of the first steps carbohydrates undergo before being utilized for respiration?

    <p>Conversion into glucose (B)</p> Signup and view all the answers

    What is the final product of glycolysis that enters the mitochondria for aerobic respiration?

    <p>Pyruvate (B)</p> Signup and view all the answers

    Which enzyme catalyzes the conversion of pyruvate to acetyl CoA in aerobic respiration?

    <p>Pyruvic dehydrogenase (C)</p> Signup and view all the answers

    Where does the complete oxidation of pyruvate occur within mitochondria?

    <p>Matrix (A)</p> Signup and view all the answers

    What is the initial stage of cellular respiration where glucose is converted into pyruvic acid?

    <p>Glycolysis (B)</p> Signup and view all the answers

    During aerobic respiration, how many molecules of NADH are produced from two molecules of pyruvic acid?

    <p>2 (B)</p> Signup and view all the answers

    What is the first molecule formed when acetyl CoA enters the Krebs cycle?

    <p>Citrate (A)</p> Signup and view all the answers

    What depends on the type of respiratory substrate used during respiration?

    <p>Respiratory quotient (A)</p> Signup and view all the answers

    Under anaerobic conditions, what process occurs after glycolysis in some organisms?

    <p>Alcohol fermentation (A)</p> Signup and view all the answers

    Which of the following coenzymes is NOT involved in the reactions catalyzed by pyruvic dehydrogenase?

    <p>FAD (D)</p> Signup and view all the answers

    What waste product is formed as a result of the complete oxidation of pyruvate during aerobic respiration?

    <p>Carbon dioxide (D)</p> Signup and view all the answers

    Where does the conversion of pyruvic acid into acetyl CoA take place?

    <p>Mitochondria (A)</p> Signup and view all the answers

    Which molecule acts as the final electron acceptor in the process of oxidative phosphorylation?

    <p>Oxygen (C)</p> Signup and view all the answers

    Which pathway directly follows the transformation of pyruvate into acetyl CoA?

    <p>Krebs cycle (A)</p> Signup and view all the answers

    What is the primary function of NADH and FADH2 produced during the Krebs cycle?

    <p>Energy transport to the electron transport chain (D)</p> Signup and view all the answers

    What process leads to energy production in the mitochondria through a series of enzyme-catalyzed reactions?

    <p>Cellular respiration (A)</p> Signup and view all the answers

    What is the primary purpose of cellular respiration?

    <p>To release energy from food materials (B)</p> Signup and view all the answers

    What is the favored substrate for respiration in living organisms?

    <p>Glucose (D)</p> Signup and view all the answers

    Which statement accurately describes the respiratory substrates?

    <p>Any organic compounds can be oxidized for energy. (A)</p> Signup and view all the answers

    Where does the oxidation of respiratory substrates primarily occur in eukaryotic cells?

    <p>In the mitochondria and cytoplasm (D)</p> Signup and view all the answers

    What is the role of ATP in cellular processes?

    <p>It serves as an energy currency (B)</p> Signup and view all the answers

    How do plants ensure the availability of oxygen for respiration?

    <p>Through the use of stomata and lenticels (D)</p> Signup and view all the answers

    What main gas do plants produce as a byproduct of respiration?

    <p>Carbon dioxide (C)</p> Signup and view all the answers

    What happens to the energy released from respiratory substrates during respiration?

    <p>It is captured as ATP through a series of reactions. (C)</p> Signup and view all the answers

    What is the primary role of glycolysis in cellular metabolism?

    <p>To partially oxidize glucose to pyruvic acid (B)</p> Signup and view all the answers

    Which type of organisms rely on anaerobic conditions for their survival?

    <p>Obligate anaerobes (A)</p> Signup and view all the answers

    What process primarily allows glucose to harness energy while minimizing heat loss?

    <p>Oxidation of glucose in multiple small steps (A)</p> Signup and view all the answers

    Where does glycolysis occur in the cell?

    <p>In the cytoplasm (A)</p> Signup and view all the answers

    Which statement about the oxygen release during photosynthesis is true?

    <p>Oxygen is released from the same cells that require it. (D)</p> Signup and view all the answers

    What is a major end product of the complete combustion of glucose?

    <p>Carbon dioxide and water (D)</p> Signup and view all the answers

    How do parenchyma cells contribute to gas exchange in plants?

    <p>By creating interconnected air spaces. (A)</p> Signup and view all the answers

    What is the first step in the breakdown of glucose under anaerobic conditions?

    <p>Glycolysis (C)</p> Signup and view all the answers

    Which compounds are typically oxidized during cellular respiration to release energy?

    <p>Carbohydrates, proteins, and fats (D)</p> Signup and view all the answers

    What gas do plants give out during respiration?

    <p>Carbon dioxide (D)</p> Signup and view all the answers

    What is the first product formed when pyruvate undergoes oxidative decarboxylation?

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

    Which coenzymes are required for the reactions catalyzed by pyruvic dehydrogenase?

    <p>NAD+ and Coenzyme A (B)</p> Signup and view all the answers

    What happens to the electrons removed from hydrogen atoms during aerobic respiration?

    <p>They are passed to molecular O2. (B)</p> Signup and view all the answers

    In which part of the mitochondria does the complete oxidation of pyruvate occur?

    <p>Matrix (B)</p> Signup and view all the answers

    What is produced in addition to Acetyl CoA during the decarboxylation of pyruvic acid?

    <p>NADH and H+ (D)</p> Signup and view all the answers

    What enzyme catalyzes the condensation of the acetyl group with oxaloacetic acid in the TCA cycle?

    <p>Citrate synthetase (C)</p> Signup and view all the answers

    Which product is not formed during the oxidative decarboxylation of pyruvate?

    <p>FADH (D)</p> Signup and view all the answers

    How many molecules of CO2 are generated from one molecule of pyruvate during aerobic respiration?

    <p>Three (D)</p> Signup and view all the answers

    What is the primary product of glycolysis from one molecule of glucose?

    <p>Two molecules of pyruvic acid (D)</p> Signup and view all the answers

    Which enzyme facilitates the conversion of sucrose to glucose and fructose in plants?

    <p>Invertase (D)</p> Signup and view all the answers

    During glycolysis, which molecule is formed after glucose-6-phosphate becomes fructose-6-phosphate?

    <p>Fructose-1,6-bisphosphate (B)</p> Signup and view all the answers

    What type of organism solely relies on glycolysis for respiration in anaerobic conditions?

    <p>Anaerobic organisms (D)</p> Signup and view all the answers

    What two monosaccharides readily enter the glycolytic pathway after being derived from sucrose?

    <p>Glucose and fructose (D)</p> Signup and view all the answers

    What is the role of hexokinase in glycolysis?

    <p>Phosphorylation of glucose (A)</p> Signup and view all the answers

    In glycolysis, what is produced as a result of the oxidation of NAD+?

    <p>NADH + H+ (B)</p> Signup and view all the answers

    Which substance is formed through a series of ten reactions in glycolysis?

    <p>Pyruvate (B)</p> Signup and view all the answers

    What is formed as a result of the isomerization of citrate?

    <p>Isocitrate (B)</p> Signup and view all the answers

    Which compound is required for the continued oxidation of acetyl CoA in the TCA cycle?

    <p>Oxaloacetic acid (B)</p> Signup and view all the answers

    Which of the following correctly describes the reduction of NAD+ in the citric acid cycle?

    <p>NAD+ is reduced to form NADH + H+ at three points (B)</p> Signup and view all the answers

    What happens to GTP during its conversion to GDP in the citric acid cycle?

    <p>It leads to ATP synthesis from ADP (A)</p> Signup and view all the answers

    How many points in the citric acid cycle result in the reduction of FAD to FADH2?

    <p>One point (A)</p> Signup and view all the answers

    What is the main function of acetyl CoA in the citric acid cycle?

    <p>To combine with oxaloacetic acid to form citric acid (D)</p> Signup and view all the answers

    Which of the following is a requirement for the regeneration of NAD+ in the citric acid cycle?

    <p>Oxidation of NADH to NAD+ (D)</p> Signup and view all the answers

    What is the main endpoint product of aerobic respiration of glucose?

    <p>Carbon dioxide and water (C)</p> Signup and view all the answers

    What is the total net gain of ATP molecules during the fermentation of one molecule of glucose?

    <p>2 ATP (A)</p> Signup and view all the answers

    Where do fatty acids enter the respiratory pathway after degradation?

    <p>As acetyl CoA (B)</p> Signup and view all the answers

    What distinguishes fermentation from aerobic respiration regarding glucose breakdown?

    <p>Fermentation is incomplete while aerobic respiration is complete. (C)</p> Signup and view all the answers

    How do amino acids enter the respiratory pathway after deamination?

    <p>At various stages within the Krebs cycle (B)</p> Signup and view all the answers

    What does the oxidation of NADH to NAD+ signify in the context of respiration?

    <p>It occurs vigorously in aerobic respiration. (B)</p> Signup and view all the answers

    What role do substrates play in the respiratory process?

    <p>Substrates can be extracted to synthesize other compounds. (B)</p> Signup and view all the answers

    Why is glucose favored as a substrate for respiration?

    <p>It can be broken down completely into simpler compounds for maximal ATP yield. (C)</p> Signup and view all the answers

    How many ATP molecules are directly synthesized from one glucose molecule during glycolysis?

    <p>4 (C)</p> Signup and view all the answers

    What is the role of NAD+ in glycolysis?

    <p>Serves as an electron acceptor (A)</p> Signup and view all the answers

    Which two molecules are produced when fructose 1, 6-bisphosphate is split?

    <p>Dihydroxyacetone phosphate and 3-phosphoglyceraldehyde (C)</p> Signup and view all the answers

    Which step of glycolysis involves substrate-level phosphorylation?

    <p>Conversion of phosphoenolpyruvate to pyruvic acid (C)</p> Signup and view all the answers

    In glycolysis, which molecule directly results from the conversion of 1, 3-bisphosphoglycerate?

    <p>3-phosphoglyceric acid (C)</p> Signup and view all the answers

    How is the energy produced during glycolysis primarily captured?

    <p>As ATP molecules (B)</p> Signup and view all the answers

    What is the first product formed when pyruvate enters the mitochondria?

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

    Which enzyme is responsible for the condensation of the acetyl group with oxaloacetic acid in the TCA cycle?

    <p>Citrate synthase (D)</p> Signup and view all the answers

    How many molecules of carbon dioxide are produced during the complete oxidation of one molecule of pyruvate?

    <p>Three (D)</p> Signup and view all the answers

    What role does NAD+ play in the reactions catalyzed by pyruvic dehydrogenase?

    <p>Electron acceptor (B)</p> Signup and view all the answers

    What is the main outcome of the TCA cycle regarding electron carriers?

    <p>Reduction of NAD+ and FAD (D)</p> Signup and view all the answers

    What process occurs in cells when oxygen is not available?

    <p>Glycolysis (D)</p> Signup and view all the answers

    Where does the passing of electrons to molecular oxygen occur during aerobic respiration?

    <p>Inner membrane of the mitochondria (B)</p> Signup and view all the answers

    What is the primary purpose of glycolysis?

    <p>To produce ATP and pyruvate from glucose (B)</p> Signup and view all the answers

    What is the fate of glucose during complete combustion?

    <p>It produces carbon dioxide, water, and energy (C)</p> Signup and view all the answers

    Which of the following statements about aerobic respiration is true?

    <p>It involves the complete oxidation of organic substances. (A)</p> Signup and view all the answers

    How do plants primarily ensure gas exchange during respiration?

    <p>By having most cells in contact with air (B)</p> Signup and view all the answers

    What is released as a byproduct during the oxidative decarboxylation of pyruvate?

    <p>Carbon dioxide (C)</p> Signup and view all the answers

    What allows plant cells to utilize some of the energy released during glucose oxidation?

    <p>Oxidizing glucose in several small steps (B)</p> Signup and view all the answers

    Which of the following is true regarding plant cells and oxygen during photosynthesis?

    <p>Oxygen is released within the cells, avoiding issues (D)</p> Signup and view all the answers

    In which part of the plant is the majority of gas exchange facilitated?

    <p>In the stems, leaves, and roots due to open structures (C)</p> Signup and view all the answers

    What term originates from the Greek words meaning 'sugar' and 'splitting'?

    <p>Glycolysis (A)</p> Signup and view all the answers

    What is the initial product formed when glucose undergoes partial oxidation in glycolysis?

    <p>Pyruvic acid (C)</p> Signup and view all the answers

    Which enzyme is responsible for phosphorylating glucose to glucose-6-phosphate?

    <p>Hexokinase (A)</p> Signup and view all the answers

    During glycolysis, which compound is directly converted from glucose-6-phosphate?

    <p>Fructose-6-phosphate (D)</p> Signup and view all the answers

    In glycolysis, which process primarily occurs in the cytoplasm of all living organisms?

    <p>Glycolysis (C)</p> Signup and view all the answers

    What are the end products of glycolysis when glucose is fully metabolized

    <p>Pyruvate and ATP (C)</p> Signup and view all the answers

    Which substrate is formed from sucrose before entering the glycolytic pathway?

    <p>Fructose (B)</p> Signup and view all the answers

    What role does ATP play during the glycolytic pathway?

    <p>It is consumed in the initial steps (B)</p> Signup and view all the answers

    How many reactions are involved in the glycolytic pathway to convert glucose to pyruvate?

    <p>Ten (A)</p> Signup and view all the answers

    What is produced during the conversion of succinyl-CoA to succinic acid?

    <p>GTP (C)</p> Signup and view all the answers

    Which compound is essential for replenishing the citric acid cycle?

    <p>Oxaloacetic acid (D)</p> Signup and view all the answers

    Which of the following statements is true regarding the production of ATP in the citric acid cycle?

    <p>ATP is produced directly during substrate level phosphorylation. (C)</p> Signup and view all the answers

    What is the main role of FAD in the citric acid cycle?

    <p>To participate in the reduction of FADH2 (A)</p> Signup and view all the answers

    What molecule is produced from the degradation of citrate during the citric acid cycle?

    <p>Isocitrate (C)</p> Signup and view all the answers

    What type of phosphorylation occurs when GTP is converted to GDP?

    <p>Substrate level phosphorylation (A)</p> Signup and view all the answers

    Which two coenzymes must be regenerated for the continued function of the citric acid cycle?

    <p>NAD+ and FAD+ (C)</p> Signup and view all the answers

    What is the respiratory quotient (RQ) when carbohydrates are fully oxidized?

    <p>1.0 (B)</p> Signup and view all the answers

    Why is the respiratory pathway considered an amphibolic pathway?

    <p>It facilitates both anabolic and catabolic reactions. (B)</p> Signup and view all the answers

    What is the respiratory quotient (RQ) for fats during respiration?

    <p>0.7 (C)</p> Signup and view all the answers

    What happens to acetyl CoA when the organism synthesizes fatty acids?

    <p>It is withdrawn from the respiratory pathway. (C)</p> Signup and view all the answers

    What is the relationship between catabolism and anabolism in living organisms according to metabolic processes?

    <p>Catabolism is related to breaking down, while anabolism relates to synthesis. (B)</p> Signup and view all the answers

    In terms of respiratory substrates, which has the RQ ratio closest to 0.9?

    <p>Proteins (A)</p> Signup and view all the answers

    What is the primary function of the respiratory pathway in relation to metabolic pathways?

    <p>To link catabolic and anabolic processes. (A)</p> Signup and view all the answers

    Which of the following statements is true regarding the breakdown of substrates for energy?

    <p>The respiratory pathway functions during both breakdown and synthesis. (A)</p> Signup and view all the answers

    What is the main pathway for the breakdown of glucose during cellular respiration?

    <p>Glycolysis (D)</p> Signup and view all the answers

    Under anaerobic conditions, what process occurs to convert pyruvate in many organisms?

    <p>Lactic acid fermentation (D)</p> Signup and view all the answers

    What is the ultimate acceptor of electrons in aerobic respiration?

    <p>Oxygen (D)</p> Signup and view all the answers

    Which of the following processes generates NADH during cellular respiration?

    <p>Both A and C (B)</p> Signup and view all the answers

    In which part of the cell does glycolysis occur?

    <p>Cytoplasm (C)</p> Signup and view all the answers

    What type of pathway is the respiratory pathway classified as?

    <p>Amphibolic (B)</p> Signup and view all the answers

    What happens to acetyl CoA after it is formed from pyruvic acid?

    <p>Enters Krebs cycle (C)</p> Signup and view all the answers

    What is the primary respiratory substrate favored by living organisms?

    <p>Glucose (D)</p> Signup and view all the answers

    What is the significance of chloroplasts in green plants?

    <p>They contain the pigments needed for photosynthesis. (A)</p> Signup and view all the answers

    Where do non-green parts of plants get their necessary food for oxidation?

    <p>They receive translocated food from green parts. (C)</p> Signup and view all the answers

    What type of nutritional strategy do herbivores primarily use?

    <p>Heterotrophic (C)</p> Signup and view all the answers

    Which of the following is a primary product of photosynthesis that plants utilize for respiration?

    <p>Starch (A)</p> Signup and view all the answers

    What characterizes saprophytes like fungi in terms of their energy acquisition?

    <p>They depend on dead and decaying matter. (C)</p> Signup and view all the answers

    What is the ultimate source of energy for all life processes as stated in the content?

    <p>Photosynthesis (C)</p> Signup and view all the answers

    What is the primary end product of glycolysis?

    <p>Pyruvic acid (D)</p> Signup and view all the answers

    Which enzyme is responsible for converting sucrose into glucose and fructose?

    <p>Invertase (C)</p> Signup and view all the answers

    In which part of the plant does photosynthesis mainly occur?

    <p>Chloroplast-containing cells (A)</p> Signup and view all the answers

    What initial step occurs during the glycolytic pathway after glucose is phosphorylated?

    <p>Isomerization to fructose-6-phosphate (B)</p> Signup and view all the answers

    In glycolysis, how many reactions occur to convert glucose into pyruvate?

    <p>10 reactions (D)</p> Signup and view all the answers

    Which molecule enters glycolysis readily after the action of invertase?

    <p>Fructose (C)</p> Signup and view all the answers

    What is produced during the phosphorylation of glucose to glucose-6-phosphate?

    <p>ATP (A)</p> Signup and view all the answers

    In the glycolytic pathway, what is the significance of NAD+?

    <p>It donates electrons during oxidation (B)</p> Signup and view all the answers

    What is produced when NADH and FADH2 are oxidized through the electron transport system?

    <p>H2O (A)</p> Signup and view all the answers

    Which complex is responsible for oxidizing NADH within the mitochondrial inner membrane?

    <p>NADH dehydrogenase (complex I) (C)</p> Signup and view all the answers

    During the citric acid cycle, how many molecules of NADH + H+ are synthesized from one glucose molecule?

    <p>8 (D)</p> Signup and view all the answers

    What is the term used to describe the breakdown of glucose to pyruvic acid?

    <p>Glycolysis (C)</p> Signup and view all the answers

    Why is oxygen critical in the respiratory process?

    <p>It acts as the final electron acceptor. (B)</p> Signup and view all the answers

    What is released as a product during glycolysis?

    <p>Pyruvic Acid (C)</p> Signup and view all the answers

    Which process relies exclusively on anaerobic conditions for energy production?

    <p>Fermentation (B)</p> Signup and view all the answers

    Which component of the electron transport system receives electrons from FADH2?

    <p>Ubiquinone (D)</p> Signup and view all the answers

    Why is oxygen not a limiting factor for photosynthesizing cells in plants?

    <p>Oxygen is produced during photosynthesis (D)</p> Signup and view all the answers

    What is the role of ADP in the mitochondrial matrix during respiration?

    <p>To be converted into ATP (B)</p> Signup and view all the answers

    How does the structure of parenchyma cells facilitate gas exchange?

    <p>They create interconnected air spaces (A)</p> Signup and view all the answers

    Which of the following statements about FADH2 is correct?

    <p>FADH2 donates electrons later in the electron transport chain than NADH. (B)</p> Signup and view all the answers

    What is a characteristic feature of the cells in thick, woody stems and roots of plants?

    <p>Only the outer layers are living (B)</p> Signup and view all the answers

    What is the total number of ATP molecules produced from one molecule of glucose via the citric acid cycle and electron transport system?

    <p>30-32 (B)</p> Signup and view all the answers

    What is produced during the complete combustion of glucose?

    <p>Carbon Dioxide and Water (D)</p> Signup and view all the answers

    What does the process of respiration utilize during glucose oxidation?

    <p>Oxygen (C)</p> Signup and view all the answers

    What is the initial stage of cellular respiration called?

    <p>Glycolysis (A)</p> Signup and view all the answers

    In aerobic respiration, what happens to pyruvic acid after glycolysis?

    <p>It is transported into the mitochondria. (C)</p> Signup and view all the answers

    Which of the following is the ultimate electron acceptor in aerobic respiration?

    <p>Oxygen (C)</p> Signup and view all the answers

    What do plants primarily use for gaseous exchange?

    <p>Stomata (D)</p> Signup and view all the answers

    What process occurs in the mitochondria after the conversion of pyruvic acid to acetyl CoA?

    <p>Krebs Cycle (B)</p> Signup and view all the answers

    Which of the following options best describes fermentation?

    <p>It occurs under anaerobic conditions. (D)</p> Signup and view all the answers

    Which of the following statements about respiratory substrates is true?

    <p>Glucose is the favored substrate for respiration. (A)</p> Signup and view all the answers

    Which statement accurately describes oxidative phosphorylation?

    <p>It utilizes an electron transport system. (B)</p> Signup and view all the answers

    What is the primary reason for considering the respiratory pathway as amphibolic?

    <p>It is involved in both breakdown and synthesis of molecules. (C)</p> Signup and view all the answers

    What is the respiratory quotient (RQ) value when carbohydrates are used as a substrate?

    <p>1.0 (C)</p> Signup and view all the answers

    Which of the following statements correctly describes the RQ when fats are used in respiration?

    <p>The RQ is less than 1. (C)</p> Signup and view all the answers

    When proteins are used as respiratory substrates, what is the approximate RQ value?

    <p>0.9 (C)</p> Signup and view all the answers

    What happens to acetyl CoA when the organism needs to synthesize fatty acids?

    <p>It is withdrawn from the respiratory pathway. (C)</p> Signup and view all the answers

    Which equation represents the complete oxidation of glucose in aerobic respiration?

    <p>$C_6H_{12}O_6 + 6O_2 ightarrow 6CO_2 + 6H_2O + Energy$ (C)</p> Signup and view all the answers

    Why is the respiratory pathway essential during both catabolic and anabolic processes?

    <p>It connects energy-producing and energy-consuming pathways. (A)</p> Signup and view all the answers

    What is the volume ratio of CO2 produced to O2 consumed when tripalmitin is the substrate for respiration?

    <p>0.7 (D)</p> Signup and view all the answers

    What is the initial product of glycolysis from glucose?

    <p>Pyruvic acid (C)</p> Signup and view all the answers

    What is the phosphorylated form of glucose produced by hexokinase?

    <p>Glucose-6-phosphate (C)</p> Signup and view all the answers

    Which statement accurately describes the pathway of fructose in glycolysis?

    <p>It follows the same steps as glucose after phosphorylation. (C)</p> Signup and view all the answers

    What does glycolysis produce as a direct byproduct during its series of reactions?

    <p>Both B and C (A)</p> Signup and view all the answers

    How many reactions are involved in the glycolytic pathway?

    <p>10 (C)</p> Signup and view all the answers

    Which compound is formed from glucose via the isomerization process in glycolysis?

    <p>Fructose-6-phosphate (A)</p> Signup and view all the answers

    What is the term for the initial step in glycolysis where glucose is phosphorylated?

    <p>Substrate-level phosphorylation (B)</p> Signup and view all the answers

    What is one of the metabolic fates of pyruvate in anaerobic conditions?

    <p>Conversion to lactic acid (A)</p> Signup and view all the answers

    Which enzyme catalyzes the conversion of pyruvic acid to ethanol during alcoholic fermentation?

    <p>Alcohol dehydrogenase (B)</p> Signup and view all the answers

    What is the primary reason yeast can be poisoned by high alcohol concentrations?

    <p>Toxic byproducts inhibit enzyme activity (C)</p> Signup and view all the answers

    In what way do lactic acid and alcoholic fermentation differ in their production?

    <p>Alcoholic fermentation produces ethanol and carbon dioxide (C)</p> Signup and view all the answers

    What is the net ATP yield from one molecule of glucose during fermentation?

    <p>2 ATP (A)</p> Signup and view all the answers

    Which process requires oxygen for complete oxidation of glucose?

    <p>Krebs cycle (C)</p> Signup and view all the answers

    What type of condition does fermentation typically occur in?

    <p>Anaerobic conditions (C)</p> Signup and view all the answers

    During lactic acid fermentation in muscle cells, what is pyruvic acid converted into?

    <p>Lactic acid (B)</p> Signup and view all the answers

    What is the respiratory quotient (RQ) when carbohydrates are completely oxidized during respiration?

    <p>1.0 (C)</p> Signup and view all the answers

    How does the respiratory quotient change when fats are used as a respiratory substrate?

    <p>The RQ is less than 1 (A)</p> Signup and view all the answers

    What is the main consequence of the oxidation of glucose in plant cells?

    <p>The release of carbon dioxide and water along with energy (D)</p> Signup and view all the answers

    Which statement best describes the role of the respiratory pathway in metabolism?

    <p>It links both catabolic and anabolic processes. (A)</p> Signup and view all the answers

    Which process allows cells to partially oxidize glucose without oxygen?

    <p>Glycolysis (B)</p> Signup and view all the answers

    What is the expected respiratory quotient (RQ) for proteins used as respiratory substrates?

    <p>0.9 (D)</p> Signup and view all the answers

    Where in the plant are the living cells primarily located in stems?

    <p>Inside the bark and in thin layers (A)</p> Signup and view all the answers

    What term describes the breakdown of glucose to pyruvic acid?

    <p>Glycolysis (A)</p> Signup and view all the answers

    What does a respiratory quotient of 0.7 indicate about substrate metabolism?

    <p>Fats are being metabolized as the primary substrate. (B)</p> Signup and view all the answers

    During aerobic respiration, what is the relationship between O2 consumption and CO2 production?

    <p>They are always in equal volumes. (B)</p> Signup and view all the answers

    What facilitates the gas exchange in most plant cells despite their structure?

    <p>Loose packing of parenchyma cells creating air spaces (C)</p> Signup and view all the answers

    What enables ATP synthesis during glucose oxidation?

    <p>Coupling large energy steps to ATP synthesis (A)</p> Signup and view all the answers

    Why is the respiratory pathway considered amphibolic?

    <p>It links energy production and metabolism of different substrates. (C)</p> Signup and view all the answers

    What kind of organisms can survive without oxygen due to their metabolic adaptations?

    <p>Obligate anaerobes (A), Facultative anaerobes (C)</p> Signup and view all the answers

    Which product of glucose combustion is primarily released as heat?

    <p>Energy (A)</p> Signup and view all the answers

    What is the primary difference in ATP production between fermentation and aerobic respiration?

    <p>Fermentation produces only 2 ATP, while aerobic respiration can produce up to 38 ATP. (C)</p> Signup and view all the answers

    How do different substrates enter the respiratory pathway for energy production?

    <p>Different substrates enter at various stages depending on their chemical structure. (A)</p> Signup and view all the answers

    What occurs to NADH during fermentation compared to aerobic respiration?

    <p>NADH is oxidized to NAD+ slowly in fermentation, but vigorously in aerobic respiration. (B)</p> Signup and view all the answers

    Why are amphibolic pathways important in cellular respiration?

    <p>They demonstrate the simultaneous interconversion of catabolic and anabolic processes. (A)</p> Signup and view all the answers

    What is the fate of glucose during fermentation?

    <p>It is partially broken down to pyruvic acid, yielding ATP. (D)</p> Signup and view all the answers

    What is required for fatty acids to enter the respiratory pathway?

    <p>They must first be broken down into glycerol and fatty acids. (B)</p> Signup and view all the answers

    Why is the respiratory process traditionally considered a catabolic process?

    <p>It focuses on breaking down substrates for energy release. (D)</p> Signup and view all the answers

    At what point do amino acids enter the respiratory pathway during metabolism?

    <p>After deamination, they enter at various stages of the Krebs cycle. (A)</p> Signup and view all the answers

    What is the primary role of oxygen in the process of respiration?

    <p>To act as the final acceptor of hydrogen (B)</p> Signup and view all the answers

    What is the function of the F0 component of ATP synthase?

    <p>To transport protons across the inner membrane (A)</p> Signup and view all the answers

    How many protons must pass through the F0 component to produce one molecule of ATP?

    <p>4 H+ (B)</p> Signup and view all the answers

    What is a significant assumption made when calculating the net gain of ATP from glucose oxidation?

    <p>Alternative substrates do not enter the respiration pathway (D)</p> Signup and view all the answers

    What type of phosphorylation occurs during the process described in respiration?

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

    What energy source is utilized for ATP synthesis during respiration compared to photophosphorylation?

    <p>Chemical energy from oxidation-reduction (D)</p> Signup and view all the answers

    Which component of ATP synthase contains the site for the synthesis of ATP?

    <p>F1 (A)</p> Signup and view all the answers

    During oxidative phosphorylation, what drives ATP synthesis?

    <p>The flow of electrons along the transport chain (C)</p> Signup and view all the answers

    Which statement about oxygen availability in plant cells during photosynthesis is accurate?

    <p>Oxygen is produced and released within the cell. (C)</p> Signup and view all the answers

    What is the primary purpose of catabolizing glucose in small steps during respiration?

    <p>To ensure energy release is coupled to ATP synthesis. (C)</p> Signup and view all the answers

    Which process occurs in the absence of oxygen in certain organisms?

    <p>Fermentation (C)</p> Signup and view all the answers

    During glycolysis, what is the primary product formed from the breakdown of glucose?

    <p>Pyruvic acid (A)</p> Signup and view all the answers

    What is the main reason cells can survive in environments lacking oxygen?

    <p>They can utilize anaerobic metabolism. (A)</p> Signup and view all the answers

    What are lenticels in plant stems important for?

    <p>Gas exchange in living cells. (B)</p> Signup and view all the answers

    How does the loose packing of parenchyma cells benefit plant respiration?

    <p>It allows for an interconnected network of air spaces. (B)</p> Signup and view all the answers

    What is the general outcome of the complete combustion of glucose?

    <p>Energy, carbon dioxide, and water are produced. (B)</p> Signup and view all the answers

    What role does oxygen play in the respiration process?

    <p>It acts as the final hydrogen acceptor. (C)</p> Signup and view all the answers

    Which statement describes the function of ATP synthase (complex V)?

    <p>It synthesizes ATP from ADP and inorganic phosphate. (C)</p> Signup and view all the answers

    What is the result of protons passing through the F0 complex of ATP synthase?

    <p>It is coupled to ATP synthesis. (D)</p> Signup and view all the answers

    Which factor can affect the theoretical net gain of ATP from glucose oxidation?

    <p>All of the above. (D)</p> Signup and view all the answers

    Under what assumption is the calculation of ATP yield primarily based?

    <p>Only glucose is respired throughout the process. (D)</p> Signup and view all the answers

    What mechanism describes the synthesis of ATP linked to the electron transport chain?

    <p>Chemiosmotic hypothesis. (D)</p> Signup and view all the answers

    How many protons need to pass through the F0 complex to synthesize one ATP molecule?

    <p>4 H+ (C)</p> Signup and view all the answers

    What is essential for the efficiency of oxidative phosphorylation?

    <p>A continuous supply of NADH. (A)</p> Signup and view all the answers

    How does the breakdown process of glucose in fermentation compare to that in aerobic respiration?

    <p>Fermentation accounts for only partial breakdown of glucose. (D)</p> Signup and view all the answers

    What must happen to fatty acids before they can enter the respiratory pathway?

    <p>They must be oxidized to fatty acyl CoA. (D)</p> Signup and view all the answers

    What is the primary reason respiration is traditionally considered a catabolic process?

    <p>Respiration breaks down substrates for energy. (C)</p> Signup and view all the answers

    Which statement is true regarding the oxidation of NADH in fermentation versus aerobic respiration?

    <p>It is slow in fermentation and vigorous in aerobic respiration. (C)</p> Signup and view all the answers

    At which point in the respiratory pathway do proteins enter after degradation?

    <p>As pyruvate or acetyl CoA. (B)</p> Signup and view all the answers

    What is the main function of glucose in cellular respiration?

    <p>It acts as the primary substrate for respiration. (B)</p> Signup and view all the answers

    Which of the following statements about respiratory substrates is incorrect?

    <p>Proteins enter the pathway unchanged. (B)</p> Signup and view all the answers

    What does the respiratory quotient (RQ) measure?

    <p>The volume of CO2 evolved to the volume of O2 consumed during respiration (A)</p> Signup and view all the answers

    What will the respiratory quotient (RQ) be when carbohydrates are the primary substrate?

    <p>1.0 (A)</p> Signup and view all the answers

    What characterizes the respiratory pathway in relation to metabolism?

    <p>It is considered an amphibolic pathway due to involvement in both anabolism and catabolism. (B)</p> Signup and view all the answers

    What is the RQ value for respiration using the fatty acid tripalmitin?

    <p>0.7 (B)</p> Signup and view all the answers

    Which of the following statements regarding catabolism and anabolism is true?

    <p>Catabolism refers to breaking down processes, while anabolism refers to synthesis. (A)</p> Signup and view all the answers

    When fatty acids are synthesized, what happens to acetyl CoA?

    <p>It is withdrawn from the respiratory pathway for synthesis. (C)</p> Signup and view all the answers

    What is the RQ value when proteins are the respiratory substrates?

    <p>0.9 (D)</p> Signup and view all the answers

    Which of the following best describes the process of breaking down fatty acids before entering the respiratory pathway?

    <p>Fatty acids must be transformed into acetyl CoA. (A)</p> Signup and view all the answers

    Which molecule is essential for the continual oxidation of acetyl CoA in the citric acid cycle?

    <p>Oxaloacetic acid (B)</p> Signup and view all the answers

    How many times is NAD+ reduced to NADH + H+ during one complete turn of the citric acid cycle?

    <p>3 (A)</p> Signup and view all the answers

    Which of the following compounds is formed as a result of substrate-level phosphorylation during the citric acid cycle?

    <p>GTP (B)</p> Signup and view all the answers

    What is the role of FAD+ during the citric acid cycle?

    <p>It is reduced to FADH2. (C)</p> Signup and view all the answers

    What is the first compound formed after citrate is isomerised?

    <p>Isocitrate (C)</p> Signup and view all the answers

    What compound is regenerated from NADH and FADH2 in the citric acid cycle?

    <p>FAD+ (B), NAD+ (D)</p> Signup and view all the answers

    Which of the following describes the process occurring when GTP is converted to GDP?

    <p>ATP is synthesized from ADP. (A)</p> Signup and view all the answers

    What is the primary function of NADH and FADH2 in the respiratory process?

    <p>To serve as electron carriers in the electron transport system (A)</p> Signup and view all the answers

    Which step in the electron transport chain is the first to oxidize NADH?

    <p>NADH dehydrogenase (Complex I) (B)</p> Signup and view all the answers

    How does the electron transport system contribute to ATP synthesis?

    <p>Through creating a proton gradient across the inner mitochondrial membrane (D)</p> Signup and view all the answers

    What is formed as a byproduct of the reaction between electrons and oxygen in the electron transport chain?

    <p>Water (A)</p> Signup and view all the answers

    What is the overall stoichiometric equation for the citric acid cycle as it relates to NADH and FADH2 production?

    <p>2 Pyruvic acid + 4 NAD+ + FAD + 2 ADP → 6 CO2 + 8 NADH + 2 FADH2 + 2 ATP (C)</p> Signup and view all the answers

    What essential component is required for the electron transport system to function effectively?

    <p>Oxygen (C)</p> Signup and view all the answers

    Which compound is produced in the inner mitochondrial membrane as part of the electron transfer process?

    <p>Ubiquinol (D)</p> Signup and view all the answers

    What does the metabolic pathway involving electron transfer between carriers in the inner mitochondrial membrane refer to?

    <p>Electron transport system (ETS) (B)</p> Signup and view all the answers

    What is the function of cytochrome c in the electron transport chain?

    <p>It acts as a mobile carrier for electrons. (A)</p> Signup and view all the answers

    Which complex is directly responsible for transferring electrons from ubiquinol to cytochrome c?

    <p>Complex III (D)</p> Signup and view all the answers

    How many ATP molecules are synthesized from one molecule of FADH2 during cellular respiration?

    <p>2 molecules of ATP (C)</p> Signup and view all the answers

    What is the overall role of oxygen in the electron transport chain?

    <p>It serves as the final electron acceptor. (A)</p> Signup and view all the answers

    What is the primary factor that determines the number of ATP molecules synthesized during respiration?

    <p>The nature of the electron donor. (A)</p> Signup and view all the answers

    Which proteins are contained within the cytochrome c oxidase complex (complex IV)?

    <p>Cytochromes a and a3 (B)</p> Signup and view all the answers

    During oxidation of NADH, how many molecules of ATP are produced?

    <p>3 molecules of ATP (D)</p> Signup and view all the answers

    What is the first product formed when glucose is phosphorylated in the glycolytic pathway?

    <p>Glucose-6-phosphate (A)</p> Signup and view all the answers

    During glycolysis, which metabolic intermediate is formed directly from glucose-6-phosphate?

    <p>Fructose-6-phosphate (B)</p> Signup and view all the answers

    What is the end product of glycolysis when glucose is partially oxidized?

    <p>Pyruvic acid (C)</p> Signup and view all the answers

    What do glucose and fructose yield after undergoing subsequent steps of metabolism in glycolysis?

    <p>ATP and NADH (C)</p> Signup and view all the answers

    What characterizes the EMP pathway in anaerobic organisms?

    <p>It is the only process in respiration. (B)</p> Signup and view all the answers

    Which of the following steps in glycolysis involves a change in the carbon structure of glucose?

    <p>Isomerization to fructose-6-phosphate (B)</p> Signup and view all the answers

    Why is glycolysis an essential process in all living organisms?

    <p>It provides the starting point for both aerobic and anaerobic respiration. (A)</p> Signup and view all the answers

    What is the primary factor that determines the metabolic fate of pyruvate?

    <p>Cellular energy demands (A)</p> Signup and view all the answers

    What is produced from the fermentation of glucose by yeast?

    <p>Ethanol and CO2 (A)</p> Signup and view all the answers

    Which enzyme is responsible for converting pyruvic acid to lactic acid in animal muscles?

    <p>Lactate dehydrogenase (C)</p> Signup and view all the answers

    What is the net gain of ATP from glucose during fermentation processes?

    <p>Around 2 ATP (A)</p> Signup and view all the answers

    In which cellular condition does fermentation typically take place?

    <p>Anaerobic conditions (B)</p> Signup and view all the answers

    What is the consequence of high alcohol concentration during yeast fermentation?

    <p>Inhibition of yeast growth (C)</p> Signup and view all the answers

    What is the major pathway for complete oxidation of glucose in eukaryotic cells?

    <p>Krebs cycle (C)</p> Signup and view all the answers

    Which of the following statements accurately describes a characteristic of fermentation?

    <p>Fermentation is a less efficient process than aerobic respiration. (D)</p> Signup and view all the answers

    What is glycolysis primarily responsible for in the process of cellular respiration?

    <p>Splitting glucose into pyruvic acid (B)</p> Signup and view all the answers

    What products are formed from the complete combustion of glucose?

    <p>Carbon dioxide and water (D)</p> Signup and view all the answers

    In certain conditions, some cells can survive without oxygen. What are these cells called?

    <p>Facultative anaerobes (B), Obligate anaerobes (C)</p> Signup and view all the answers

    What is one of the primary reasons why plant cells can effectively manage gas exchange?

    <p>Most cells are close to the surface and have a network of air spaces. (B)</p> Signup and view all the answers

    What is the first step in the anaerobic breakdown of glucose?

    <p>Glycolysis (D)</p> Signup and view all the answers

    What is produced as a result of glycolysis besides pyruvic acid?

    <p>Both B and C (C)</p> Signup and view all the answers

    What will the respiratory quotient (RQ) be when fats are used as a substrate?

    <p>0.7 (A)</p> Signup and view all the answers

    Why is it efficient for cells to oxidize glucose in several small steps?

    <p>To efficiently convert energy into ATP (B)</p> Signup and view all the answers

    During the synthesis of fatty acids, what happens to acetyl CoA?

    <p>It is withdrawn from the respiratory pathway. (B)</p> Signup and view all the answers

    What is the respiratory quotient (RQ) for proteins when they are used as substrates?

    <p>0.9 (D)</p> Signup and view all the answers

    In the context of catabolism and anabolism, which term refers to the breakdown processes within a living organism?

    <p>Catabolism (A)</p> Signup and view all the answers

    What ratio describes the relationship between the volume of CO2 evolved and the volume of O2 consumed during respiration?

    <p>Respiratory quotient (C)</p> Signup and view all the answers

    What is one key feature of the respiratory pathway regarding its involvement in metabolism?

    <p>It facilitates both energy breakdown and synthesis processes. (B)</p> Signup and view all the answers

    What is the primary substrate for cellular respiration in most living organisms?

    <p>Glucose (B)</p> Signup and view all the answers

    Which process occurs in the cytoplasm during cellular respiration?

    <p>Glycolysis (D)</p> Signup and view all the answers

    Which electron carrier accepts electrons in the electron transport system?

    <p>O2 (B)</p> Signup and view all the answers

    Which part of the mitochondria does the Krebs cycle occur?

    <p>Matrix (A)</p> Signup and view all the answers

    In what process is ATP synthesized through the action of electron carriers?

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

    What distinguishes aerobic respiration from fermentation?

    <p>Aerobic respiration requires oxygen (C)</p> Signup and view all the answers

    What is the function of NADH + H+ in cellular respiration?

    <p>They are used to synthesize ATP in the electron transport chain (A)</p> Signup and view all the answers

    Flashcards

    Ubiquinol oxidation

    Ubiquinol is oxidized, transferring electrons to cytochrome bc1 complex.

    Cytochrome c function

    Small protein, moves electrons between complex III and IV.

    Complex IV (Cytochrome c oxidase)

    Contains cytochromes a and a3, and copper centers, final electron acceptor.

    Electron transport chain (ETC)

    Chain of electron carriers, coupled to ATP synthesis.

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    ATP synthase (complex V)

    Enzyme producing ATP from ADP and inorganic phosphate.

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    NADH and ATP

    Oxidizing one NADH molecule creates 3 ATP molecules.

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    FADH2 and ATP

    Oxidizing one FADH2 molecule creates 2 ATP molecules.

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    Oxygen's Role in Respiration

    Oxygen is crucial at the end of respiration, accepting electrons from ETC.

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    Cellular Respiration

    The process by which cells break down food molecules to release energy and store it in ATP.

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    ATP

    Adenosine Triphosphate, the energy currency of cells, used for various energy-requiring processes.

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    Respiratory Substrates

    The molecules that are oxidized during respiration to release energy, mainly carbohydrates, but also proteins, fats, and organic acids.

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    Oxidation in Respiration

    The process of breaking down C-C bonds in complex molecules by removing electrons, releasing energy.

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    Energy Release in Respiration

    Energy released through oxidation is not directly used, but trapped in ATP via a series of controlled steps.

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    Plant Respiration

    Plants also respire, using oxygen and releasing carbon dioxide, but they have no specialized respiratory organs.

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    Plant Gas Exchange

    Plants exchange gases through stomata and lenticels, each plant part taking care of its own needs.

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    Why Plants Don't Need Respiratory Organs

    Plants respire at lower rates than animals and have efficient gas exchange systems, making specialized organs unnecessary.

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    What is glycolysis?

    A metabolic process that breaks down glucose into pyruvate, producing a small amount of ATP and NADH.

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    What happens to pyruvate in anaerobic conditions?

    When oxygen is unavailable, pyruvate undergoes fermentation, converting it into either lactic acid or ethanol. This process regenerates NAD+ for glycolysis.

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    What is lactic acid fermentation?

    Pyruvate is reduced to lactate by lactate dehydrogenase, regenerating NAD+ for glycolysis. Happens in muscle cells during strenuous exercise.

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    What is alcoholic fermentation?

    Pyruvate is decarboxylated to acetaldehyde, which is then reduced to ethanol by alcohol dehydrogenase, also regenerating NAD+.

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    What is the energy yield of fermentation?

    Fermentation releases a very small amount of energy, less than 7% of the energy stored in glucose. This is because glucose is not completely oxidized.

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    What is aerobic respiration?

    The complete oxidation of glucose to CO2 and H2O within mitochondria, requiring oxygen and producing a significant amount of ATP.

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    What is the role of NADH+H+ in fermentation?

    NADH+H+ is used as a reducing agent to convert pyruvate into either lactic acid or ethanol. It is then reoxidized back to NAD+ to sustain glycolysis.

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    What is the net ATP yield of fermentation?

    The net ATP yield from fermenting one glucose molecule is only 2 ATP. This is because the ATP generated from glycolysis is used for the fermentation process.

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    Anaerobic Respiration

    Energy production without oxygen, using fermentation to partially break down glucose and generate ATP.

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    Aerobic Respiration

    Energy production with oxygen, completely breaking down glucose into CO2 & H2O for maximum ATP yield.

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    ATP Yield Comparison

    Aerobic respiration creates significantly more ATP per glucose molecule than anaerobic fermentation.

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    Amphibolic Pathway

    A metabolic pathway that serves both catabolic (breakdown) and anabolic (synthesis) purposes, such as the respiratory pathway.

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    Glucose as a Substrate

    Glucose is the preferred substrate for respiration, as it enters the pathway at the beginning.

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    Alternative Substrates

    Other molecules like fats and proteins can be used for respiration, but they enter the pathway later.

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    Fat Breakdown

    Fats are broken down into glycerol and fatty acids, which enter the respiratory pathway later.

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    Protein Breakdown

    Proteins are broken down into amino acids, which enter the respiratory pathway depending on their structure.

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    Citric Acid Cycle: Key Players

    The Citric Acid Cycle (CAC) uses acetyl-CoA, a 2-carbon molecule, and oxaloacetic acid (OAA), a 4-carbon molecule, to generate energy. It's a cyclical process with key intermediates like citric acid, α-ketoglutaric acid, and succinyl-CoA.

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    CAC: Decarboxylation

    During the Citric Acid Cycle, two decarboxylation steps occur, where CO2 is released. This happens during the conversion of α-ketoglutaric acid to succinyl-CoA and isocitrate to α-ketoglutaric acid.

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    Substrate-Level Phosphorylation

    In the CAC, a molecule of GTP is synthesized in a substrate-level phosphorylation reaction where a phosphate group is directly transferred from a substrate (succinyl-CoA) to GDP.

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    CAC: Redox Reactions

    The CAC involves redox reactions, where electrons are transferred. NAD+ is reduced to NADH + H+ at three points in the cycle. FAD+ is reduced to FADH2 at one point.

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    CAC: OAA Replenishment

    The CAC requires the continued replenishment of oxaloacetic acid (OAA). This is crucial for the cycle to continue operating and generating energy from acetyl-CoA.

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    CAC: NAD+ and FAD+ Regeneration

    The CAC also requires the regeneration of NAD+ and FAD+ from NADH and FADH2 respectively. This is essential for maintaining the redox balance of the cycle.

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    Isocitrate Isomerization

    The CAC starts with citrate, which is then isomerized to isocitrate. Isomerization means rearranging the atoms within a molecule, changing its structure.

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    α-ketoglutaric Acid

    α-ketoglutaric acid is a key intermediate in the Citric Acid Cycle. Formed by the decarboxylation of isocitrate and further processed to succinyl-CoA.

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    What is cellular respiration?

    The process where cells break down organic molecules, like glucose, to release energy stored within their chemical bonds, using this energy to make ATP.

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    What are respiratory substrates?

    These are molecules that cells break down during respiration to release energy. The most common is glucose, but fats and proteins can also be used.

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    What is the Krebs cycle?

    A series of chemical reactions that occur in the mitochondria, breaking down pyruvate further and generating electron carriers (NADH and FADH2) used in the next stage.

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    What is the electron transport chain?

    A series of protein complexes in the mitochondria that use the energy from electron carriers (like NADH and FADH2) to create a proton gradient across the inner membrane, which then drives ATP production.

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    What is oxidative phosphorylation?

    The process of ATP synthesis driven by the electron transport chain and proton gradient, which uses oxygen as the final electron acceptor.

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    Electron Transport Chain

    A chain of protein complexes (I-IV) embedded in the inner mitochondrial membrane, transferring electrons from NADH and FADH2 to oxygen, generating a proton gradient for ATP production.

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    ATP Production from NADH & FADH2

    One NADH molecule produces 3 ATP molecules, while one FADH2 molecule produces 2 ATP molecules. This difference is due to the entry point in the electron transport chain.

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    Why do living organisms breathe?

    Living organisms require energy to perform life processes like growth, movement, and reproduction. This energy is obtained through the breakdown of food molecules, which involves the process of respiration.

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    What is the source of energy for life?

    The energy for life comes from the breakdown of food molecules, which are ultimately derived from photosynthesis in plants. Photosynthesis converts sunlight into chemical energy stored in carbohydrates.

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    Do all plants respire?

    Yes, all plants respire, even though only some parts of the plant can photosynthesize. All parts of the plant need energy for basic functions.

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    What is the role of photosynthesis in respiration?

    Photosynthesis provides the carbohydrates that are used as the primary source of energy for respiration. This energy is stored in the chemical bonds of carbohydrates.

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    What is respiration?

    Respiration is the process by which organisms break down food molecules to release energy stored in their chemical bonds. This energy is used to carry out various life processes.

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    What is the difference between autotrophs and heterotrophs?

    Autotrophs, like plants, can create their own food through photosynthesis. Heterotrophs, like animals, obtain their food by consuming other organisms.

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    What happens to food during respiration?

    Food molecules are broken down into simpler molecules, releasing energy stored within their chemical bonds. This energy is stored in a usable form called ATP.

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    Why is respiration important?

    Respiration provides the energy necessary for all living organisms to function. This includes growth, movement, repair, reproduction, and other vital processes.

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    Glycolysis: ATP Usage

    Glycolysis uses ATP in two steps: converting glucose to glucose 6-phosphate and fructose 6-phosphate to fructose 1, 6-bisphosphate.

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    Glycolysis: Fructose 1, 6-bisphosphate

    Fructose 1, 6-bisphosphate is split into dihydroxyacetone phosphate and 3-phosphoglyceraldehyde (PGAL).

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    Glycolysis: NADH Production

    NAD+ is converted to NADH + H+ when 3-phosphoglyceraldehyde (PGAL) is converted to 1, 3-bisphosphoglycerate (BPGA).

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    Glycolysis: ATP Synthesis

    Two ATP molecules are directly synthesized during glycolysis from one glucose molecule: one during the conversion of BPGA to PGA and another during the conversion of PEP to pyruvate.

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    Glycolysis: Key Product

    The key product of glycolysis is pyruvate, a 3-carbon molecule.

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    Glycolysis: Energy Yield

    Glycolysis produces a net gain of 2 ATP molecules per glucose molecule.

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    What happens to pyruvate after glycolysis?

    Pyruvate can be further processed through aerobic respiration (with oxygen) or fermentation (without oxygen) depending on the availability of oxygen.

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    Glycolysis

    The initial stage of respiration, occurring in the cytoplasm. It breaks down glucose into two pyruvate molecules, generating a small amount of ATP.

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    Krebs Cycle

    A series of reactions in the mitochondria that further break down pyruvate, generating electron carriers (NADH and FADH2) used in the next stage.

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    Oxidative Phosphorylation

    The process of ATP synthesis driven by the electron transport chain and proton gradient. Oxygen is the final electron acceptor.

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    Respiratory Quotient (RQ)

    The ratio of CO2 released to O2 consumed during respiration, indicating the type of respiratory substrate being used.

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    RQ for Carbohydrates

    When carbohydrates are the primary respiratory substrate, RQ is 1 because equal amounts of CO2 and O2 are involved during respiration.

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    RQ for Fats

    When fats are used, RQ is less than 1 because more oxygen is consumed than CO2 produced.

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    RQ for Proteins

    When proteins are used, RQ is around 0.9 because the ratio of CO2 produced to O2 consumed is slightly less than 1.

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    Catabolism

    Metabolic processes breaking down complex molecules into simpler ones, releasing energy.

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    Anabolism

    Metabolic processes building complex molecules from simpler ones, requiring energy.

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    Interrelationship of Metabolic Pathways

    Different metabolic pathways are interconnected, with the respiratory pathway playing a central role in both breakdown and synthesis of various molecules.

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    Why Plants Don't Need Special Respiratory Organs

    Plants don't have specialized respiratory organs because they have efficient gas exchange systems through stomata and lenticels, enabling each part of the plant to take care of its own respiratory needs.

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    How Does O2 Availability Affect Plant Respiration?

    Plants don't have an oxygen shortage for respiration because O2 is released during photosynthesis within the cells and most plant cells are close to the surface, enabling them to easily access air.

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    Why Do Cells Break Down Glucose Step-by-Step?

    Cells break down glucose in multiple steps during respiration to capture the energy released more efficiently. This allows the energy to be used for ATP synthesis and prevent a lot of energy being lost as heat.

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    What Happens to Pyruvate Without Oxygen?

    Without oxygen, pyruvate undergoes anaerobic fermentation, producing either lactic acid or ethanol. This regenerates NAD+ for glycolysis to continue, but releases much less energy than aerobic respiration.

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    How Does Aerobic Respiration Differ from Anaerobic Respiration?

    Aerobic respiration requires oxygen and completely breaks down glucose into CO2 and H2O, resulting in a much higher ATP yield than anaerobic respiration. Anaerobic respiration doesn't use oxygen and only partially breaks down glucose.

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    What are the Key Differences Between Lactic Acid and Alcoholic Fermentation?

    Both lactic acid and alcoholic fermentation occur without oxygen, but lactic acid fermentation produces lactic acid, whereas alcoholic fermentation produces ethanol and CO2. They both regenerate NAD+ for glycolysis to continue.

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    Why do organisms breathe?

    Living organisms need energy to survive - breathing is part of the process of obtaining that energy from food.

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    Where does energy for life come from?

    Energy for all life comes from breaking down food, which is made by plants through photosynthesis.

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    Plant Respiration: Oxygen?

    Plants don't face oxygen shortage during respiration because they produce oxygen as a by-product of photosynthesis and most plant cells are close to the surface, allowing easy air access.

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    Why Step-by-Step Glucose Breakdown?

    Cells break down glucose slowly in many steps during respiration to capture energy more efficiently, preventing most of it from being lost as heat. This energy is then used for ATP production.

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    Pyruvate's Fate Without Oxygen

    When oxygen is unavailable, pyruvate undergoes anaerobic fermentation, producing either lactic acid or ethanol. This regenerates NAD+ for glycolysis to continue but yields much less energy than aerobic respiration.

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    Aerobic vs. Anaerobic: The Difference

    Aerobic respiration uses oxygen to completely break down glucose into CO2 and H2O, resulting in a high ATP yield. Anaerobic respiration doesn't use oxygen and only partially breaks down glucose, producing much less ATP.

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    Lactic Acid vs. Alcoholic Fermentation

    Both occur without oxygen, but lactic acid fermentation produces lactic acid, while alcoholic fermentation produces ethanol and CO2. They both regenerate NAD+ to sustain glycolysis.

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    Energy Source for Life?

    Energy for all life comes from breaking down food, which is made by plants using sunlight for photosynthesis. This process converts light into chemical energy stored in carbohydrates.

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    Pyruvate's Journey

    Pyruvate, produced from glycolysis, is transported into the mitochondria for further breakdown in aerobic respiration.

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    Oxidative Decarboxylation

    The removal of carbon dioxide and hydrogen atoms from pyruvate, forming acetyl CoA, a key molecule for the Krebs cycle, along with NADH.

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    ATP Production

    ATP is synthesized from ADP and inorganic phosphate using the energy from the proton gradient established by the electron transport chain.

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    Why are alternative substrates used?

    Other molecules besides glucose can be used for respiration because they can enter the respiratory pathway at different points, depending on their structure.

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    What is the role of fats in respiration?

    Fats are broken down into glycerol and fatty acids, which can then enter the respiratory pathway.

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    How are proteins used for respiration?

    Proteins are broken down into amino acids, which can enter the respiratory pathway at different stages, depending on their structure.

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    Is respiration truly catabolic?

    While respiration involves the breakdown of molecules, it is also an amphibolic pathway, meaning it plays a role in building molecules as well, by drawing on intermediates from the pathway.

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    How is glucose used for respiration?

    Glucose, a readily available sugar, is the preferred substrate for respiration, entering the pathway at the very beginning.

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    What is fermentation?

    A process that occurs without oxygen, where pyruvate is converted to either lactic acid or ethanol, regenerating NAD+ for glycolysis to continue. It releases less energy than aerobic respiration.

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    What is the respiratory quotient (RQ)?

    The ratio of CO2 released to O2 consumed during respiration, indicating the type of respiratory substrate being used. It can tell us if cells are using carbohydrates, fats, or proteins for energy.

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    ATP: Energy Currency

    ATP is the main energy molecule used by cells for processes like growth, movement, and repair. It's like the 'coin' cells use to pay for energy.

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    Pyruvate's Fate

    After glycolysis, pyruvate's fate depends on oxygen availability. With oxygen, it enters the mitochondria for further breakdown. Without oxygen, it undergoes fermentation.

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    Fermentation

    A process that occurs without oxygen, converting pyruvate into either lactic acid or ethanol. Regenerates NAD+ for glycolysis.

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    Glycolysis: Starting Point

    Glycolysis begins with the breakdown of glucose, a six-carbon sugar, into two molecules of pyruvate, each containing three carbons.

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    Pyruvate's Fate: With Oxygen

    When oxygen is available, pyruvate enters the mitochondria to continue respiration via the Krebs Cycle and electron transport chain.

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    RQ Values: Different Substrates

    When carbohydrates are the primary respiratory substrate, RQ is 1. When fats are used, RQ is less than 1. When proteins are used, RQ is around 0.9.

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    Mitochondrial Role

    Mitochondria are the powerhouses of the cell, where the majority of ATP production occurs during aerobic respiration.

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    Decarboxylation in Citric Acid Cycle

    Two steps in the Citric Acid Cycle involve the removal of a carbon dioxide (CO2) molecule from the intermediate molecules. This process is called decarboxylation.

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    NAD+ and FAD+ Regeneration

    The Citric Acid Cycle requires regeneration of NAD+ and FAD+ through the reduction of NADH and FADH2. This keeps the process running smoothly.

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    Replenishing Oxaloacetic Acid

    For the Citric Acid Cycle to continue, it's crucial to maintain a steady supply of oxaloacetic acid (OAA), a 4-carbon molecule that starts the cycle.

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    How does NAD+ relate to NADH?

    NAD+ is an electron carrier that accepts electrons during the Citric Acid Cycle, becoming reduced to NADH + H+. The NADH produced can then transfer these electrons to other processes, like the electron transport chain.

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    Succinyl-CoA Formation

    During the Citric Acid Cycle, α-ketoglutaric acid is converted into succinyl-CoA, a 4-carbon molecule, through a series of steps.

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    Fats in Respiration

    Fats are broken down into glycerol and fatty acids, which can then enter the respiratory pathway to be used for energy production.

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    Proteins in Respiration

    Proteins are broken down into amino acids, which can enter the respiratory pathway at various stages, depending on their structure, to release energy.

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    Plant Respiration: O2?

    Plants don't face an oxygen shortage for respiration because they produce oxygen as a by-product of photosynthesis. Also, most plant cells are near the surface, allowing easy air access.

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    Glycolysis: Location

    Glycolysis occurs in the cytoplasm of the cell, the fluid that fills the space between the cell membrane and the nucleus.

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    Glycolysis: Role

    Glycolysis is the first stage of respiration, where glucose is partially broken down into two molecules of pyruvate, generating a small amount of ATP.

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    Fermentation: Purpose

    Fermentation occurs when oxygen is unavailable, allowing glycolysis to continue by regenerating NAD+, which is essential for the process.

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    Fermentation: Energy Yield

    Fermentation produces a very small amount of energy compared to aerobic respiration because glucose is not completely oxidized.

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    Pyruvate's Fate in Aerobic Respiration

    After glycolysis, pyruvate is transported into the mitochondria where it undergoes oxidative decarboxylation to form acetyl CoA, a key component for the Krebs cycle.

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    Alternative Respiratory Substrates

    Other molecules besides glucose, like fats and proteins, can be used for respiration. They enter the pathway at different points, depending on their structure.

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    Why is Respiration Considered Amphibolic?

    Respiration is not just about breaking down molecules, but also plays a role in building complex molecules, drawing on intermediates from the pathway.

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    What are alternative substrates?

    Molecules like fats and proteins can be used for respiration when glucose isn't available. They enter the pathway at different points depending on their structure.

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    What is ATP: Energy Currency?

    ATP is the main energy molecule used by cells for processes like growth, movement, and repair. It's like the 'coin' cells use to pay for energy.

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    Decarboxylation in the Citric Acid Cycle

    The citric acid cycle involves two steps where carbon dioxide (CO2) is released from the molecule. This process is called decarboxylation.

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    Redox Reactions in the Citric Acid Cycle

    The citric acid cycle involves several redox reactions where electrons are transferred. NAD+ is reduced to NADH + H+ at three points, and FAD+ is reduced to FADH2 at one point.

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    OAA Replenishment

    The citric acid cycle requires a constant supply of oxaloacetic acid (OAA) to continue operating. This is crucial for accepting acetyl-CoA and generating energy.

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    Succinyl-CoA Oxidation

    Succinyl-CoA is oxidized during the citric acid cycle, ultimately leading to the regeneration of oxaloacetic acid (OAA). This oxidation allows the cycle to continue operating.

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    Electron Transport System (ETS)

    A series of protein complexes in the inner mitochondrial membrane that transfer electrons from NADH and FADH2 to oxygen, generating a proton gradient for ATP production.

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    What is the role of oxygen in respiration?

    Oxygen is the final electron acceptor in the electron transport chain. It combines with electrons and protons to form water, and this process is essential for maintaining the flow of electrons through the chain.

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    How do the electron carriers NADH and FADH2 contribute to ATP production?

    NADH and FADH2 molecules carry electrons from the Krebs cycle to the electron transport chain. The movement of electrons through the chain is coupled to the pumping of protons across the inner mitochondrial membrane, creating a gradient that drives ATP synthesis.

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    What is the difference between ATP production from NADH and FADH2?

    NADH produces 3 ATP molecules per molecule oxidized, while FADH2 only produces 2 ATP molecules. This difference is because FADH2 enters the electron transport chain at a later stage, contributing less to the proton gradient.

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    What is the energy yield of the electron transport chain?

    The electron transport chain is responsible for the majority of ATP production in respiration. It generates around 34 ATP molecules per glucose molecule, significantly more than the 2 ATP molecules produced during glycolysis.

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    Why is the electron transport chain coupled to ATP synthesis?

    The electron transport chain is coupled to ATP synthesis because the energy released by the flow of electrons through the chain is used to pump protons across the inner mitochondrial membrane, creating a gradient that drives ATP production. This coupling ensures that the energy released during electron transfer is harnessed for ATP synthesis.

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    What is the importance of the electron transport chain in respiration?

    The electron transport chain is the final stage of respiration and plays a crucial role in generating the majority of the ATP required by cells. Without this chain, cells would not be able to produce enough energy to perform essential functions.

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    Respiration

    The process by which organisms break down food molecules to release the energy stored within their chemical bonds.

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    Photosynthesis

    The process used by plants to convert light energy into chemical energy stored in carbohydrate molecules.

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    Glycolysis: What is it?

    Glycolysis is the initial stage of respiration, happening in the cytoplasm. It breaks down glucose into two molecules of pyruvate, generating a small amount of ATP.

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    Pyruvate: What Happens Next?

    Pyruvate can be further processed through aerobic respiration (with oxygen) or fermentation (without oxygen) depending on the availability of oxygen.

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    What other molecules, besides glucose, can be used in respiration?

    Fats and proteins can also be used in respiration, but they enter the pathway at different points, depending on their structure.

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    Pyruvate

    A three-carbon molecule produced at the end of glycolysis. Its fate depends on oxygen availability: it can be further processed in aerobic respiration or undergo fermentation.

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    Lactic Acid Fermentation

    A type of fermentation that produces lactic acid from pyruvate. This occurs in muscle cells during strenuous exercise.

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    Alcoholic Fermentation

    A type of fermentation that produces ethanol and CO2 from pyruvate. This occurs in yeast and some bacteria.

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    Energy Yield of Fermentation

    Fermentation releases a very small amount of energy, less than 7% of the energy stored in glucose. This is because glucose is not completely oxidized.

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    Net ATP Yield of Fermentation

    The net ATP yield from fermenting one glucose molecule is only 2 ATP. This is because the ATP generated from glycolysis is used for the fermentation process.

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    Maximum Alcohol Concentration

    Yeasts poison themselves to death when the concentration of alcohol reaches about 13 per cent. This is the maximum concentration of alcohol in beverages that are naturally fermented.

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    ATP Synthase

    An enzyme that uses the proton gradient created by the electron transport chain to produce ATP from ADP and inorganic phosphate.

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    Chemiosmotic Hypothesis

    This theory explains how ATP is produced through the movement of protons across the inner mitochondrial membrane during respiration.

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    Glucose's Role

    Glucose is the preferred substrate for respiration, as it enters the pathway at the very beginning.

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    Ubiquinone

    A mobile electron carrier within the inner mitochondrial membrane. It accepts electrons from both NADH dehydrogenase (complex I) and succinate dehydrogenase (complex II) in the electron transport chain.

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    Cytochrome c

    A small protein that acts as an electron carrier between Complex III (cytochrome bc1 complex) and Complex IV (cytochrome c oxidase) in the electron transport chain.

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    NADH Dehydrogenase (Complex I)

    The first protein complex in the electron transport chain. It accepts electrons from NADH and transfers them to ubiquinone.

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    Cytochrome c Oxidase (Complex IV)

    The final electron acceptor in the electron transport chain. It contains cytochromes a and a3 and copper centers and transfers electrons to oxygen to form water.

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    FADH2 Dehydrogenase (Complex II)

    A protein complex in the electron transport chain that accepts electrons from FADH2 and transfers them to ubiquinone.

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    Why is oxygen not a problem for plants during photosynthesis?

    Plants produce oxygen as a byproduct of photosynthesis, so they have a readily available supply within their cells.

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    How does glucose breakdown differ in aerobic and anaerobic respiration?

    Aerobic respiration uses oxygen to completely break down glucose into carbon dioxide and water, releasing much more energy than anaerobic respiration, which doesn't use oxygen and only partially breaks down glucose.

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    What is the purpose of fermentation?

    Fermentation occurs when oxygen is unavailable, converting pyruvate into lactic acid or ethanol. This regenerates NAD+ for glycolysis to continue and produce a small amount of energy.

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    What is the importance of ATP?

    ATP is the energy currency of cells, supplying energy for various processes like growth, movement, and repair.

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    How are fats used as a respiratory substrate?

    Fats are broken down into glycerol and fatty acids, which can then enter the respiratory pathway.

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    Why are alternative substrates used for respiration?

    Besides glucose, other molecules, like fats and proteins, can be used as respiratory substrates because they can enter the pathway at different points.

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    Citric Acid Cycle: Purpose

    The Citric Acid Cycle (also known as the Krebs Cycle) is a series of reactions that break down acetyl-CoA, producing energy carriers (NADH and FADH2) that power the electron transport chain.

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    What is Isomerization?

    Isomerization is a process where the atoms within a molecule are rearranged, leading to a change in its structure but not its chemical formula. An example is the conversion of citrate to isocitrate in the Citric Acid Cycle.

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    What is Decarboxylation?

    Decarboxylation is a chemical reaction where a carboxyl group (COOH) is removed from a molecule, releasing carbon dioxide (CO2) as a byproduct. This process happens twice in the Citric Acid Cycle.

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    Oxaloacetic Acid (OAA): Replenishment

    The Citric Acid Cycle requires a constant supply of oxaloacetic acid (OAA) to continue functioning. This is necessary for the cycle to accept acetyl-CoA and generate energy.

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    Regeneration of NAD+ and FAD+

    The Citric Acid Cycle relies on the regeneration of NAD+ and FAD+ from NADH and FADH2 respectively. This maintains the redox balance within the cycle, ensuring its smooth operation.

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    α-ketoglutaric Acid: A Key Intermediate

    α-ketoglutaric acid is a crucial intermediate in the Citric Acid Cycle. This 5-carbon molecule is formed by the decarboxylation of isocitrate and is further processed to succinyl-CoA.

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    Respiratory Balance Sheet

    A theoretical calculation of the net gain of ATP for each glucose molecule oxidized, taking into account the energy yields of glycolysis, the Krebs cycle, and oxidative phosphorylation.

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    Why is oxygen essential for respiration?

    Oxygen acts as the final electron acceptor in the electron transport chain, drawing electrons through the chain and releasing the energy needed to power ATP synthesis.

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    What is the role of the proton gradient in ATP synthesis?

    The proton gradient, created by the electron transport chain, provides the energy for ATP synthase to synthesize ATP from ADP and inorganic phosphate.

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    How does the ETC generate energy?

    The ETC passes electrons from electron carriers like NADH and FADH2 to oxygen, releasing energy at each step to pump protons across the mitochondrial membrane, creating a gradient that powers ATP synthase.

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    Why do cells break down glucose in a step-by-step process?

    Breaking down glucose slowly in multiple steps allows for a more efficient capture of energy. This prevents a lot of energy being lost as heat.

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    What happens to pyruvate when there's no oxygen?

    Pyruvate undergoes anaerobic fermentation, producing either lactic acid or ethanol, which regenerates NAD+ for glycolysis to continue. This process releases far less energy than aerobic respiration.

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    What is the difference between aerobic and anaerobic respiration?

    Aerobic respiration requires oxygen and completely breaks down glucose into CO2 and H2O, resulting in a high ATP yield. Anaerobic respiration doesn't use oxygen and only partially breaks down glucose.

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    What are the main differences between lactic acid and alcoholic fermentation?

    Both processes occur without oxygen, but lactic acid fermentation produces lactic acid, while alcoholic fermentation produces ethanol and CO2. Both regenerate NAD+ to keep glycolysis going.

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    What is ATP's role in the cell?

    ATP is the primary energy currency of cells, powering vital processes like growth, movement, and repair. It's like the 'coin' cells use to pay for these functions.

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    What happens to proteins during respiration?

    Proteins are broken down into amino acids, which can enter the respiratory pathway at various points. Their breakdown yields energy and contributes to the cell's overall energy budget.

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    Cytochrome c: Electron Shuttle

    Cytochrome c is a small protein that acts as a mobile carrier, transporting electrons between Complex III and Complex IV in the electron transport chain.

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    Complex IV: Final Electron Acceptor

    Complex IV, also known as cytochrome c oxidase, contains cytochromes a and a3, and two copper centers. It accepts electrons from cytochrome c and transfers them to oxygen to form water, the final step in the electron transport chain.

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    ATP Synthase (Complex V): Energy Production

    ATP synthase is an enzyme complex that uses the energy from the proton gradient created by the electron transport chain to synthesize ATP from ADP and inorganic phosphate.

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    NADH Yield in Electron Transport Chain

    Oxidation of one molecule of NADH in the electron transport chain produces 3 molecules of ATP.

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    FADH2 Yield in Electron Transport Chain

    Oxidation of one molecule of FADH2 in the electron transport chain produces 2 molecules of ATP.

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    Electron Transport Chain: Linking Energy

    The electron transport chain is a series of protein complexes embedded in the inner mitochondrial membrane, transferring electrons from NADH and FADH2, ultimately to oxygen. This electron flow fuels the creation of a proton gradient across the membrane, which powers ATP synthesis.

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    Why do plants not need respiratory organs?

    Plants have efficient gas exchange systems through stomata and lenticels, allowing each part of the plant to take care of its own respiratory needs. This eliminates the need for specialized respiratory organs.

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    Why break down glucose step-by-step in respiration?

    Cells break down glucose slowly and in many steps during respiration to capture energy more efficiently, preventing most of it from being lost as heat. This energy is then harnessed for ATP production.

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    Aerobic vs. Anaerobic Respiration: The difference

    Aerobic respiration uses oxygen to completely break down glucose into CO2 and H2O, resulting in a high ATP yield. Anaerobic respiration does not use oxygen and only partially breaks down glucose, producing much less ATP.

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    Lactic Acid vs Alcoholic Fermentation: Key difference

    Both fermentations occur without oxygen, but lactic acid fermentation produces lactic acid, while alcoholic fermentation produces ethanol and CO2. Both regenerate NAD+ for glycolysis.

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    What is the energy source for life?

    Energy for all life comes from breaking down food, which is made by plants using sunlight for photosynthesis. This process converts light into chemical energy stored in carbohydrates.

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    Glycolysis: Where?

    Glycolysis takes place in the cytoplasm of the cell, the fluid inside cells.

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    Glycolysis: What's broken down?

    Glycolysis breaks down glucose, a simple sugar, into two molecules of pyruvate.

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    Glycolysis: What's produced?

    Glycolysis produces a small amount of ATP (energy) and NADH, an electron carrier.

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    What is ATP?

    ATP is the main energy molecule used by cells for processes like growth, movement, and repair.

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    What is NADH?

    NADH is an electron carrier that delivers electrons to the electron transport chain for ATP production.

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    Why is fermentation hazardous to organisms?

    Fermentation produces either acid (lactic acid) or alcohol (ethanol), which can be detrimental to organisms in high concentrations.

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    What is the maximum alcohol concentration in naturally fermented beverages?

    The maximum concentration of alcohol in naturally fermented beverages is about 13%. Yeasts are killed by higher concentrations.

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    Study Notes

    Respiration in Plants

    • Plants, like all living things, require energy for daily activities.
    • Energy comes from oxidizing food.
    • Photosynthesis is how green plants/cyanobacteria produce their own food.
    • Plants don't have to "eat" food like animals—they convert light into chemical energy.
    • This chemical energy is stored in the bonds of carbohydrates like sugars (glucose, sucrose, starch).
    • These molecules provide energy through respiration.

    Breathing in Plants

    • All plant parts don't necessarily need the same amount of gas exchange.
    • Gas exchange happens in leaves, stems, and roots.
    • Stomata and lenticels allow gas exchange.
    • Plants don't have respiratory systems like animals—gas exchange occurs by diffusion.
    • Plants don't need as much gas exchange as animals—each plant part handles its own needs.
    • During photosynthesis, O₂ need is less of a concern.

    Glycolysis

    • The breakdown of glucose to pyruvate.
    • Occurs in the cytoplasm of all cells.
    • Partial oxidation—releases some energy in a stepwise process.
    • Creates two ATP molecules per glucose.
    • Creates NADH which store energy.

    Fermentation

    • Anaerobic process—occurs when oxygen is unavailable.
    • Breakdown of glucose in absence of oxygen.
    • Produces lactic acid (animals) or ethanol/CO₂ (yeast/bacteria)
    • Very little energy is released compared to aerobic respiration.
    • Important biochemical pathway for life.

    Krebs Cycle

    • Also known as the citric acid cycle.
    • Occurs within mitochondria matrix.
    • Pyruvate from glycolysis enters and is converted to acetyl CoA.
    • Continues the breakdown of glucose and releases CO2.
    • Further extracts energy, storing it as NADH and FADH2.

    Electron Transport System (ETS)

    • A series of protein complexes embedded in the mitochondrial inner membrane.
    • Takes electrons from NADH and FADH2, passing them along the chain.
    • Energy released pumps protons (H+) across the inner membrane.
    • The proton gradient drives ATP synthesis through ATP synthase.
    • Produces a large number of ATP molecules.

    Respiratory Quotient (RQ)

    • Ratio of CO₂ released to O₂ consumed during respiration.
    • Varies depending on the respiratory substrate.
    • Carbohydrates: RQ = 1
    • Fats: RQ < 1
    • Proteins: RQ ~ 0.9

    Amphibolic Pathway

    • Respiratory pathway isn't solely catabolic (breakdown).
    • It also contributes to anabolic processes (biosynthesis of other molecules).
    • Molecules generated during respiration can be repurposed in various metabolic functions.

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    Respiration in Plants PDF

    Description

    Explore the fascinating processes of respiration and photosynthesis in plants. This quiz covers how plants generate energy from light and the mechanisms of gas exchange in various plant parts. Test your understanding of glycolysis and the unique respiration methods in plants.

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