Photosynthesis and Chloroplasts
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Questions and Answers

Where are the stacks of thylakoids located within chloroplasts?

  • Stroma
  • Grana (correct)
  • Outer membrane
  • Photosystems

    • Which part of the chloroplast is responsible for carrying out light-dependent reactions?

  • Stroma
  • Thylakoids
  • Photosystem I (correct)
  • Outer membrane

    • What is the main product generated in cyclic photophosphorylation?

  • ADP
  • Oxygen
  • ATP (correct)
  • Glucose

    • What process describes the production of ATP in photosynthesis?

    <p>Photophosphorylation</p> Signup and view all the answers

    What is the initial acceptor of electrons in the electron transport chain during light-dependent reactions?

    <p>Chlorophyll</p> Signup and view all the answers

    Which photosystem provides the excited electrons for cyclic photophosphorylation?

    <p>Photosystem I</p> Signup and view all the answers

    What is the space between the thylakoids and the outer chloroplast membrane called?

    <p>Stroma</p> Signup and view all the answers

    What is the main purpose of producing enzymes only when their substrate is present?

    <p>To avoid unnecessary enzyme production</p> Signup and view all the answers

    How do cells benefit from catabolizing metabolites to produce lots of energy?

    <p>By enhancing the efficiency of cellular activities</p> Signup and view all the answers

    Why is it important for eukaryotic cells to separate metabolic processes in membrane-bound organelles?

    <p>To compartmentalize different metabolic activities</p> Signup and view all the answers

    What is the primary role of allosteric regulation in enzyme function?

    <p>To regulate enzyme activity based on cellular conditions</p> Signup and view all the answers

    How does feedback inhibition contribute to the regulation of metabolic pathways?

    <p>By inhibiting excessive accumulation of end products</p> Signup and view all the answers

    Which process is associated with controlling enzyme production needed for metabolic pathways?

    <p>Synthesizing metabolites only when needed</p> Signup and view all the answers

    In what way do cells regulate the availability of cofactors to affect metabolic pathways?

    <p>By regulating pathways through cofactor control</p> Signup and view all the answers

    Which precursor metabolite is used to produce ribose and deoxyribose for nucleotide biosynthesis?

    <p>Ribose 5-phosphate</p> Signup and view all the answers

    What is the main source of phosphate for nucleotide biosynthesis?

    <p>ATP</p> Signup and view all the answers

    Which amino acids contribute to the production of purines and pyrimidines for nucleotide biosynthesis?

    <p>Glutamine and Aspartic acid</p> Signup and view all the answers

    How are catabolic and anabolic pathways related in terms of energy utilization?

    <p>Energy released in catabolic pathways is used to drive anabolic pathways</p> Signup and view all the answers

    What term is used to describe reactions that can function as both anabolic and catabolic pathways as needed?

    <p>Amphibolic</p> Signup and view all the answers

    Which component is NOT part of a nucleotide structure?

    <p>Adenine base</p> Signup and view all the answers

    What is the role of folic acid in nucleotide biosynthesis?

    <p>Aiding in the production of purines and pyrimidines</p> Signup and view all the answers

    Which type of organisms use inorganic compounds like H2S as a source of electrons for photosynthesis?

    <p>Anoxygenic organisms</p> Signup and view all the answers

    In noncyclic photophosphorylation, what is the role of photosystem II?

    <p>Replenishes electrons to PS II</p> Signup and view all the answers

    Which molecules are produced during the reduction step of the Calvin-Benson cycle?

    <p>Glyceraldehyde 3-phosphate (G3P)</p> Signup and view all the answers

    What drives the synthesis of glucose by carbon fixation in the light-independent pathway of photosynthesis?

    <p>ATP and NADPH</p> Signup and view all the answers

    What are amphibolic reactions in metabolism?

    <p>Reactions that proceed towards catabolism or anabolism depending on cell needs</p> Signup and view all the answers

    What is the ultimate product of the Calvin-Benson cycle?

    <p>Glucose</p> Signup and view all the answers

    What is the source of electrons for oxygenic organisms during photosynthesis?

    <p>H2O</p> Signup and view all the answers

    Which process involves the production of sugars, starch, cellulose, glycogen, and peptidoglycan from noncarbohydrate precursors?

    <p>Gluconeogenesis</p> Signup and view all the answers

    How many reactions are unique to gluconeogenesis?

    <p>Four</p> Signup and view all the answers

    Which process involves the synthesis of triglycerides from glycerol and fatty acids?

    <p>Lipid biosynthesis</p> Signup and view all the answers

    What type of amino acid synthesis involves the addition of an amine group from ammonia to a precursor metabolite?

    <p>Amination</p> Signup and view all the answers

    Which type of lipids require long synthesis pathways and lots of energy for their production?

    <p>Waxes</p> Signup and view all the answers

    What are essential amino acids?

    <p>Amino acids that must be obtained through diet</p> Signup and view all the answers

    Which metabolic pathway involves the seven reactions that are simply the reverse of glycolysis reactions?

    <p>Gluconeogenesis</p> Signup and view all the answers

    What is the role of nicotinamide adenine dinucleotide (NAD+) in metabolic pathways?

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

    During dehydrogenation reactions, which molecule loses an electron?

    <p>The electron donor</p> Signup and view all the answers

    What is the main function of flavin adenine dinucleotide (FAD) in metabolic pathways?

    <p>Transfer electrons</p> Signup and view all the answers

    In redox reactions, what happens to the electron donor?

    <p>Is oxidized</p> Signup and view all the answers

    What is the significance of phosphorylation in energy storage?

    <p>Adds a phosphate group to molecules</p> Signup and view all the answers

    Which statement accurately describes anabolic reactions in cellular metabolism?

    <p>Require ATP energy</p> Signup and view all the answers

    What type of reactions involve the transfer of electrons in metabolism?

    <p>Dehydrogenation</p> Signup and view all the answers

    What are organic cofactors also known as?

    <p>Coenzymes</p> Signup and view all the answers

    What term is used to describe RNA molecules that function as catalysts?

    <p>Ribozymes</p> Signup and view all the answers

    What is the function of ribosomal ribozymes in eukaryotes?

    <p>Process RNA molecules</p> Signup and view all the answers

    What determines enzyme-substrate specificity in enzymology?

    <p>Complementary shapes of active sites and substrates</p> Signup and view all the answers

    Which model describes the phenomenon where the active site of an enzyme changes shape upon substrate binding?

    <p>Induced Fit model</p> Signup and view all the answers

    How do enzymes affect the activation energy of a chemical reaction?

    <p>Decrease it</p> Signup and view all the answers

    What can influence the rate of enzymatic reactions?

    <p>Temperature, pH, enzyme and substrate concentration, and presence of inhibitors</p> Signup and view all the answers

    What might result in the denaturation of enzymes?

    <p>A change in shape due to physical or chemical factors.</p> Signup and view all the answers

    During glycolysis, how many net ATP molecules are produced?

    <p>2</p> Signup and view all the answers

    Which stage of glycolysis involves the splitting of glucose into two molecules of pyruvic acid?

    <p>Lysis</p> Signup and view all the answers

    In glycolysis, which molecule is produced by substrate-level phosphorylation?

    <p>ATP</p> Signup and view all the answers

    What determines whether pyruvate is directed to the citric acid cycle or fermentation reactions?

    <p>Availability of final electron acceptors</p> Signup and view all the answers

    Which stage of cellular respiration involves the production of acetyl-CoA?

    <p>Synthesis of acetyl-CoA</p> Signup and view all the answers

    Where does the production of acetyl-CoA in cellular respiration begin?

    <p>Decarboxylation of pyruvic acid</p> Signup and view all the answers

    How many stages are involved in cellular respiration?

    <p>3</p> Signup and view all the answers

    Which metabolic pathway yields the most ATP molecules from the aerobic respiration of glucose?

    <p>Embden-Meyerhof pathway</p> Signup and view all the answers

    What is the main purpose of fermentation in cells?

    <p>To generate NADPH</p> Signup and view all the answers

    Which pathway is used by only a few bacteria, utilizes different enzymes, and yields precursor metabolites and NADPH?

    <p>Entner-Doudoroff pathway</p> Signup and view all the answers

    During aerobic respiration of glucose, where does the citric acid cycle occur?

    <p>Mitochondrial matrix</p> Signup and view all the answers

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

    <p>To produce ATP molecules</p> Signup and view all the answers

    Which molecule serves as the final electron acceptor in fermentation when complete cellular respiration electron acceptors are unavailable?

    <p>NAD+</p> Signup and view all the answers

    What is the purpose of the pentose phosphate pathway during glucose catabolism?

    <p>To provide precursor metabolites and NADPH for important molecule synthesis</p> Signup and view all the answers

    What is the main function of the citric acid cycle?

    <p>Generate ATP and FADH2</p> Signup and view all the answers

    Where does the electron transport chain take place in eukaryotic cells?

    <p>Mitochondrial matrix</p> Signup and view all the answers

    What is the primary role of the proton gradient in the electron transport chain?

    <p>Generate ATP through chemiosmosis</p> Signup and view all the answers

    What distinguishes lithotrophs from most organisms in terms of electron donors?

    <p>Harness energy from inorganic compounds</p> Signup and view all the answers

    Which cellular component houses the electron transport chains in prokaryotes?

    <p>Cytoplasmic membrane</p> Signup and view all the answers

    What is the common name for the tricarboxylic acid cycle?

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

    Which process utilizes energy from electrons to pump protons across a membrane?

    <p>Chemiosmosis</p> Signup and view all the answers

    What is the final electron acceptor in the electron transport chain?

    <p>Oxygen</p> Signup and view all the answers

    What is the primary purpose of synthesizing metabolites only when they are needed?

    <p>To avoid wasting energy on unnecessary metabolic processes</p> Signup and view all the answers

    How does allosteric regulation contribute to enzyme function?

    <p>By modulating enzyme activity based on cellular needs</p> Signup and view all the answers

    What is the purpose of feedback inhibition in metabolic pathways?

    <p>To prevent the accumulation of excess metabolites</p> Signup and view all the answers

    Which mechanism separates metabolic processes in eukaryotes?

    <p>Membrane-bound organelles</p> Signup and view all the answers

    What is the main function of controlling gene expression in cells?

    <p>To control the production of enzymes necessary for metabolic pathways</p> Signup and view all the answers

    How do cells benefit from producing enzymes only when their substrate is present?

    <p>By conserving energy and resources for necessary processes</p> Signup and view all the answers

    In what way do regulatory mechanisms impact metabolic pathways?

    <p>By influencing enzyme activity and metabolite synthesis</p> Signup and view all the answers

    What is a key role of Catabolizing metabolites to produce lots of energy?

    <p>To generate a significant amount of energy for cellular functions</p> Signup and view all the answers

    What is the primary function of adenosine triphosphate (ATP) in metabolism?

    <p>Storing energy in the bonds</p> Signup and view all the answers

    In metabolism, what is the role of catalytic enzymes?

    <p>Breaking down nutrients into precursor metabolites</p> Signup and view all the answers

    What is the main source of energy for metabolism?

    <p>Catabolism</p> Signup and view all the answers

    Which process involves assembling larger molecules using precursor metabolites and energy?

    <p>Anabolic reactions</p> Signup and view all the answers

    What is the primary function of the citric acid cycle in cellular respiration?

    <p>Generation of ATP molecules</p> Signup and view all the answers

    Which metabolic pathway involves the breakdown of proteins?

    <p>Lipid catabolism</p> Signup and view all the answers

    In photosynthesis, where do light-independent reactions take place?

    <p>Calvin-Benson cycle</p> Signup and view all the answers

    What is the main role of the pentose phosphate pathway during glucose catabolism?

    <p>Reduction of NADP+ to NADPH</p> Signup and view all the answers

    What is the primary difference between oxidative phosphorylation and photophosphorylation?

    <p>The source of energy</p> Signup and view all the answers

    Which category of enzymes is responsible for joining molecules together?

    <p>Ligases</p> Signup and view all the answers

    What type of cofactors include ions such as iron, magnesium, zinc, or copper?

    <p>Inorganic cofactors</p> Signup and view all the answers

    Which mode of action involves rearranging atoms in a molecule?

    <p>Isomerases</p> Signup and view all the answers

    What is the main function of transferases among the six categories of enzymes?

    <p>Transfer functional groups</p> Signup and view all the answers

    What is the final product of substrate-level phosphorylation?

    <p>ATP</p> Signup and view all the answers

    Which enzyme category is involved in oxidizing or reducing reactions?

    <p>Oxidoreductases</p> Signup and view all the answers

    What distinguishes apoenzymes from complete protein enzymes?

    <p><em>Apoenzymes</em> are inactive until they bind with a nonprotein cofactor.</p> Signup and view all the answers

    What is the purpose of chemiosmosis in the electron transport chain?

    <p>Synthesizing ATP</p> Signup and view all the answers

    Which category of carrier molecules is responsible for creating a proton gradient across a membrane during chemiosmosis?

    <p>Ubiquinones</p> Signup and view all the answers

    How many molecules of NADH are oxidized to yield approximately 34 molecules of ATP during chemiosmosis?

    <p>10</p> Signup and view all the answers

    In anaerobic respiration, what serves as the final electron acceptor instead of oxygen?

    <p>Sulfate</p> Signup and view all the answers

    What is the primary function of cytochromes in the electron transport system?

    <p>Transporting electrons</p> Signup and view all the answers

    Which process results in the synthesis of ATP through the flow of protons through ATP synthase channels?

    <p><strong>Oxidative phosphorylation</strong></p> Signup and view all the answers

    During chemiosmosis, what provides potential energy known as a proton motive force?

    <p><strong>Oxidation of NADH</strong></p> Signup and view all the answers

    What is the role of ribozymes in eukaryotic cells?

    <p>Process RNA molecules</p> Signup and view all the answers

    How are substrates related to the active sites of enzymes?

    <p>Fit onto specifically shaped active sites</p> Signup and view all the answers

    What is the consequence of high temperatures on enzyme activity?

    <p>Denatures enzymes by changing their shape</p> Signup and view all the answers

    What effect does the presence of inhibitors have on enzyme reactions?

    <p>Slows down or stops enzymatic activity</p> Signup and view all the answers

    How is enzyme-substrate specificity determined?

    <p>By the complementary shapes of active sites and substrates</p> Signup and view all the answers

    What happens after an enzyme binds to a substrate in catabolism?

    <p>The enzyme separates from the two products formed</p> Signup and view all the answers

    What model describes the phenomenon where the active site of an enzyme can change shape upon substrate binding?

    <p>Induced-fit model</p> Signup and view all the answers

    How do physical and chemical factors like temperature and pH affect enzymatic activity?

    <p>Denature enzymes, affecting their ability to function</p> Signup and view all the answers

    Which type of metabolic reactions break down nutrients into precursor metabolites?

    <p>Catabolic reactions</p> Signup and view all the answers

    What is the primary function of ATP in metabolism?

    <p>Storing and transferring energy</p> Signup and view all the answers

    Which process involves the assembly of larger molecules using precursor metabolites and energy?

    <p>Anabolic reactions</p> Signup and view all the answers

    What is the main outcome of lipid catabolism?

    <p>ATP production</p> Signup and view all the answers

    During cellular respiration, what role do catalytic enzymes play?

    <p>Breaking down nutrients into precursor metabolites</p> Signup and view all the answers

    What is the key function of carbohydrate biosynthesis in metabolism?

    <p>Synthesizing carbohydrates from simpler precursors</p> Signup and view all the answers

    In terms of metabolism, what describes the role of photosynthesis?

    <p>Utilizes light energy to build organic molecules from CO2 and water</p> Signup and view all the answers

    What is the primary purpose of the tricarboxylic acid cycle in cells?

    <p>Oxidizing acetyl-CoA to produce NADH and FADH2 for electron transport chain</p> Signup and view all the answers

    What happens when a cell has doubled in size?

    <p>It typically divides into two cells</p> Signup and view all the answers

    What type of reactions synthesize macromolecules and use ATP energy?

    <p>Anabolic reactions</p> Signup and view all the answers

    What do oxidation-reduction (redox) reactions involve the transfer of?

    <p>Electrons</p> Signup and view all the answers

    Which molecules are often required in metabolic pathways as electron carriers?

    <p>Nicotinamide adenine dinucleotide (NAD+), nicotinamide adenine dinucleotide phosphate (NADP+), and flavin adenine dinucleotide (FAD)</p> Signup and view all the answers

    What is the role of ATP in energy storage?

    <p>It stores energy in high-energy phosphate bonds</p> Signup and view all the answers

    What is characteristic of catabolic pathways?

    <p>They are exergonic and break down nutrient molecules</p> Signup and view all the answers

    What occurs during dehydrogenation reactions?

    <p>An electron donor loses an electron and is oxidized</p> Signup and view all the answers

    What is phosphorylation in the context of cellular processes?

    <p>The addition of inorganic phosphate to a molecule to store energy</p> Signup and view all the answers

    Where are the two photosystems, PS I and PS II, located within the chloroplast?

    <p>Thylakoids</p> Signup and view all the answers

    What process generates ATP in photosynthesis through a proton motive force?

    <p>Photophosphorylation</p> Signup and view all the answers

    Which chlorophyll molecule is excited by transferred energy and passes electrons to the electron transport chain?

    <p>Reaction center chlorophyll</p> Signup and view all the answers

    What is the primary function of photosystem I in cyclic photophosphorylation?

    <p>Provide excited electrons</p> Signup and view all the answers

    What is the general term for the light absorption and redox reactions of photosynthesis?

    <p>Light-dependent reactions</p> Signup and view all the answers

    In photosynthesis, where is ATP synthesized during cyclic photophosphorylation?

    <p>By chemiosmosis</p> Signup and view all the answers

    What role does the space between thylakoids and the outer chloroplast membrane play in photosynthesis?

    <p>It is the stroma where dark reactions occur</p> Signup and view all the answers

    What is the primary function of the citric acid cycle?

    <p>Synthesize ATP</p> Signup and view all the answers

    In the electron transport chain, what is the role of lithotrophs compared to most organisms?

    <p>Utilize inorganic electron donors</p> Signup and view all the answers

    What is the main source of energy produced in the electron transport chain?

    <p>Proton motive force</p> Signup and view all the answers

    Which enzymes are responsible for the hydration reactions in the citric acid cycle?

    <p>Hydratase enzymes</p> Signup and view all the answers

    What is the final electron acceptor in the electron transport chain?

    <p>Oxygen</p> Signup and view all the answers

    How many ATP molecules are formed for every two molecules of acetyl-CoA that enter the citric acid cycle?

    <p>4 ATP</p> Signup and view all the answers

    Which organelle houses the electron transport chains in eukaryotic cells?

    <p>Mitochondria</p> Signup and view all the answers

    What is the process used to generate ATP by utilizing a proton gradient across a membrane?

    <p>Chemiosmosis</p> Signup and view all the answers

    What is the primary function of photophosphorylation?

    <p>Phosphorylation of ADP using inorganic phosphate and energy from light</p> Signup and view all the answers

    Which category of enzymes is responsible for splitting molecules without using water?

    <p>Lyases</p> Signup and view all the answers

    What distinguishes protein enzymes composed of apoenzymes and nonprotein cofactors from complete protein enzymes?

    <p>They are not functional by themselves</p> Signup and view all the answers

    What is the role of isomerases among the six categories of enzymes?

    <p>Rearrange atoms in a molecule</p> Signup and view all the answers

    What type of cofactors are made from vitamins and include NAD+ and FAD?

    <p>Organic cofactors</p> Signup and view all the answers

    How are organic catalysts, like enzymes, different from inorganic catalysts?

    <p>Enzymes are not permanently changed in the process</p> Signup and view all the answers

    What is the primary function of transferases among the six categories of enzymes?

    <p>Transfer functional groups</p> Signup and view all the answers

    What is the main purpose of hydrolases among the six categories of enzymes?

    <p><strong>Split molecules without using water</strong></p> Signup and view all the answers

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