100 Bioenergetics Questions and Answers.

100 BIOENERGETICS QUESTIONS AND ANSWERS

The following are top 100 questions and answers in bioenergetics. Kindly note that these are concise answers that should be elaborated in tests situations:

 

  1. Q: What is bioenergetics?

   A: Bioenergetics is the study of energy flow and transformation within living organisms.

 

  1. Q: What is ATP?

   A: ATP (adenosine triphosphate) is a high-energy molecule used as the primary energy currency in cells.

 

  1. Q: What cellular process generates ATP?

   A: ATP is generated during cellular respiration through processes like glycolysis, the citric acid cycle, and oxidative phosphorylation.

 

  1. Q: Where does glycolysis occur in the cell?

   A: Glycolysis occurs in the cytoplasm of the cell.

 

  1. Q: What is the net yield of ATP molecules in glycolysis?

   A: The net yield of ATP molecules in glycolysis is 2 ATP molecules.

 

  1. Q: What is the end product of glycolysis?

   A: The end products of glycolysis are two molecules of pyruvate.

 

  1. Q: What are the three main stages of cellular respiration?

   A: The three main stages of cellular respiration are glycolysis, the citric acid cycle (Krebs cycle), and oxidative phosphorylation.

 

  1. Q: Where does the citric acid cycle take place in the cell?

   A: The citric acid cycle takes place in the mitochondria.

 

  1. Q: What is the final electron acceptor in the electron transport chain?

   A: Oxygen is the final electron acceptor in the electron transport chain.

 

  1. Q: What is the purpose of the electron transport chain?

    A: The electron transport chain generates a proton gradient across the inner mitochondrial membrane, driving ATP synthesis.

 

  1. Q: What is the role of NADH in cellular respiration?

    A: NADH carries high-energy electrons to the electron transport chain, where they are used to produce ATP.

 

  1. Q: What is the function of FADH2 in cellular respiration?

    A: FADH2 also delivers electrons to the electron transport chain to produce ATP.

 

  1. Q: What is the main function of mitochondria in a cell?

    A: Mitochondria are the sites of cellular respiration, where ATP is produced.

 

  1. Q: What is the difference between aerobic and anaerobic respiration?

    A: Aerobic respiration uses oxygen as the final electron acceptor, while anaerobic respiration uses other molecules.

 

  1. Q: What is lactic acid fermentation?

    A: Lactic acid fermentation is an anaerobic process that converts pyruvate into lactic acid, regenerating NAD+ for glycolysis to continue.

 

  1. Q: What organisms perform alcoholic fermentation?

    A: Yeast and some bacteria perform alcoholic fermentation.

 

  1. Q: What is the main product of alcoholic fermentation?

    A: The main products of alcoholic fermentation are ethanol and carbon dioxide.

 

  1. Q: What is the primary photosynthetic pigment in plants?

    A: Chlorophyll a is the primary photosynthetic pigment in plants.

 

  1. Q: What is the purpose of photosynthesis?

    A: Photosynthesis converts light energy into chemical energy (glucose) in plants and some bacteria.

 

  1. Q: Where does photosynthesis occur in plants?

    A: Photosynthesis occurs in the chloroplasts of plant cells.

 

  1. Q: What is the chemical equation for photosynthesis?

    A: 6CO2 + 6H2O + light energy → C6H12O6 + 6O2

 

  1. Q: What are the two main stages of photosynthesis?

    A: The two main stages of photosynthesis are the light-dependent reactions and the Calvin cycle (light-independent reactions).

 

  1. Q: What happens during the light-dependent reactions of photosynthesis?

    A: Light-dependent reactions use light energy to produce ATP and NADPH, releasing oxygen as a byproduct.

 

  1. Q: What is the role of the Calvin cycle in photosynthesis?

    A: The Calvin cycle uses ATP and NADPH to convert carbon dioxide into glucose.

 

  1. Q: What is photophosphorylation?

    A: Photophosphorylation is the process of generating ATP using light energy in photosynthesis.

 

  1. Q: What is the difference between C3, C4, and CAM plants?

    A: C3, C4, and CAM plants are different types of photosynthetic pathways based on how they fix carbon dioxide.

 

  1. Q: What is the primary function of light-harvesting complexes in photosynthesis?

    A: Light-harvesting complexes absorb light and transfer the energy to the reaction center, where photochemistry occurs.

 

  1. Q: What are the products of the light-dependent reactions?

    A: The products of the light-dependent reactions are ATP, NADPH, and oxygen.

 

  1. Q: How is ATP synthase used in photosynthesis?

    A: ATP synthase generates ATP by using the proton gradient formed during the light-dependent reactions.

 

  1. Q: What is the overall purpose of the light-dependent reactions?

    A: The light-dependent reactions capture and convert light energy into chemical energy (ATP and NADPH).

 

  1. Q: What is the Calvin cycle also known as?

    A: The Calvin cycle is also known as the dark reactions or light-independent reactions.

 

  1. Q: Where does the Calvin cycle take place in the chloroplast?

    A: The Calvin cycle takes place in the stroma of the chloroplast.

 

  1. Q: What molecule is initially fixed during the Calvin cycle?

    A: The Calvin cycle initially fixes carbon dioxide (CO2) using the enzyme RuBisCO.

 

  1. Q: What is the first stable product of the Calvin cycle?

    A: The first stable product of the Calvin cycle is 3-phosphoglycerate (3-PGA).

 

  1. Q: What is the primary function of NADPH in the Calvin cycle?

    A: NADPH provides the reducing power to convert 3-PGA into G3P (glyceraldehyde 3-phosphate).

 

  1. Q: How many turns of the Calvin cycle are needed to produce one molecule of glucose?

    A: Six turns of the Calvin cycle are needed to produce one molecule of glucose.

 

  1. Q: How does the Calvin cycle regenerate RuBP (ribulose-1,5-bisphosphate)?

    A: The last step of the Calvin cycle regenerates RuBP using ATP.

 

  1. Q: What are the products of the Calvin cycle?

    A: The products of the Calvin cycle are G3P (glyceraldehyde 3-phosphate) and ADP.

 

  1. Q: What is the role of stomata in photosynthesis?

    A: Stomata are small pores on plant leaves that allow carbon dioxide to enter for photosynthesis while releasing oxygen and water vapor.

 

  1. Q: What are the three phases of the Calvin cycle?

    A: The three phases of the Calvin cycle are carbon fixation, reduction, and regeneration of RuBP.

 

  1. Q: How is the rate of photosynthesis affected by light intensity?

    A: The rate of photosynthesis increases with increasing light intensity, up to a certain point where it plateaus.

 

  1. Q: What is the role of carotenoids in photosynthesis?

 

 

    A: Carotenoids help protect plants from excess light energy by dissipating it as heat.

 

  1. Q: How does temperature affect photosynthesis?

    A: Photosynthesis is temperature-sensitive; it increases with temperature until it reaches an optimum point, beyond which it declines.

 

  1. Q: What is the role of the photosystems in the light-dependent reactions?

    A: Photosystems are pigment-protein complexes that capture light energy and transfer it to reaction centers.

 

  1. Q: What is the primary function of NADP+ in photosynthesis?

    A: NADP+ is reduced to NADPH during the light-dependent reactions, carrying energy and high-energy electrons to the Calvin cycle.

 

  1. Q: What are the reactants of the light-dependent reactions?

    A: The reactants of the light-dependent reactions are light, water, ADP, and NADP+.

 

  1. Q: What is photolysis in photosynthesis?

    A: Photolysis is the process of breaking down water molecules into oxygen, protons, and electrons during the light-dependent reactions.

 

  1. Q: What is the role of cytochrome complex in the electron transport chain?

    A: The cytochrome complex is a protein complex in the electron transport chain that transfers electrons from cytochrome b to cytochrome c.

 

  1. Q: How does carbon dioxide enter the leaf for photosynthesis?

    A: Carbon dioxide enters the leaf through stomata.

 

  1. Q: How is the energy from the sun captured in photosynthesis?

    A: Energy from the sun is captured by chlorophyll and other pigments in the light-harvesting complexes.

 

  1. Q: What is the relationship between photosynthesis and cellular respiration?

    A: Photosynthesis produces glucose and oxygen, which are used as reactants in cellular respiration to produce ATP and carbon dioxide.

 

  1. Q: How is the energy stored in glucose released in cellular respiration?

    A: The energy stored in glucose is released through a series of redox reactions during glycolysis and the citric acid cycle.

 

  1. Q: What is the purpose of the ETC (electron transport chain) in cellular respiration?

    A: The ETC generates a proton gradient that drives ATP synthesis during oxidative phosphorylation.

 

  1. Q: Why is oxygen necessary for aerobic respiration?

    A: Oxygen is the final electron acceptor in the electron transport chain, allowing the efficient production of ATP.

 

  1. Q: What happens to pyruvate in aerobic respiration?

    A: In aerobic respiration, pyruvate enters the mitochondria and is further oxidized in the citric acid cycle.

 

  1. Q: What is the role of Coenzyme Q (CoQ) in the electron transport chain?

    A: Coenzyme Q transfers electrons from complex I and II to complex III in the electron transport chain.

 

  1. Q: What is the net yield of ATP from one molecule of glucose in cellular respiration?

    A: The net yield of ATP from one molecule of glucose in cellular respiration is 36-38 ATP molecules, depending on the cell type.

 

  1. Q: What is the function of the inner mitochondrial membrane in cellular respiration?

    A: The inner mitochondrial membrane houses the electron transport chain and ATP synthase, crucial for ATP production.

 

  1. Q: What is the role of acetyl-CoA in the citric acid cycle?

    A: Acetyl-CoA is the starting molecule in the citric acid cycle, and it combines with oxaloacetate to form citrate.

 

  1. Q: What are the electron carriers in the electron transport chain?

    A: The main electron carriers in the electron transport chain are NADH and FADH2.

 

  1. Q: How is the proton gradient established during cellular respiration?

    A: The proton gradient is established by the movement of protons across the inner mitochondrial membrane during the electron transport chain.

 

  1. Q: What is the role of oxygen in the electron transport chain?

    A: Oxygen is the final electron acceptor in the electron transport chain, combining with protons to form water.

 

  1. Q: What is the purpose of substrate-level phosphorylation in glycolysis?

    A: Substrate-level phosphorylation generates ATP by directly transferring a phosphate group from a high-energy substrate to ADP.

 

  1. Q: Why is the citric acid cycle also called the Krebs cycle?

    A: The citric acid cycle is named after its discoverer, Hans Krebs.

 

  1. Q: What happens to the carbon atoms in glucose during the citric acid cycle?

    A: The carbon atoms in glucose are completely oxidized to carbon dioxide during the citric acid cycle.

 

  1. Q: What is the role of the F1F0 ATP synthase complex in cellular respiration?

    A: The F1F0 ATP synthase complex produces ATP from ADP and inorganic phosphate using the proton gradient.

 

  1. Q: What is the role of dehydrogenases in cellular respiration?

    A: Dehydrogenases remove hydrogen atoms from substrates, transferring them to electron carriers like NAD+ and FAD.

 

  1. Q: What are the steps involved in the electron transport chain?

    A: The steps involved in the electron transport chain are: Complex I (NADH dehydrogenase), Complex II (Succinate dehydrogenase), Coenzyme Q, Complex III (Cytochrome bc1 complex), Cytochrome c, Complex IV (Cytochrome c oxidase).

 

  1. Q: What is the role of the mitochondrial matrix in cellular respiration?

    A: The mitochondrial matrix houses the enzymes necessary for the citric acid cycle.

 

  1. Q: What is the final product of the citric acid cycle?

    A: The final products of the citric acid cycle are ATP, NADH, FADH2, and carbon dioxide.

 

  1. Q: What happens during the preparatory reaction before the citric acid cycle?

    A: During the preparatory reaction, pyruvate is converted into acetyl-CoA.

 

  1. Q: How many carbon atoms are in one molecule of glucose?

    A: One molecule of glucose contains six carbon atoms.

 

  1. Q: Why is the proton gradient important for ATP synthesis?

    A: The proton gradient drives the rotation of ATP synthase, enabling it to generate ATP from ADP and inorganic phosphate.

 

  1. Q: What is the role of ATP synthase in cellular respiration?

    A: ATP synthase produces ATP using the energy of the proton gradient formed during the electron transport chain.

 

  1. Q: What are the two main types of fermentation?

    A: The two main types of fermentation are lactic acid fermentation and alcoholic fermentation.

 

  1. Q: What is the purpose of fermentation in cells?

    A: Fermentation allows the regeneration of NAD+ from NADH, ensuring that glycolysis can continue in the absence of oxygen.

 

  1. Q: What type of respiration occurs in human muscle cells during intense exercise?

    A: Lactic acid fermentation occurs in human muscle cells during intense exercise when oxygen becomes limited.

 

  1. Q: How many molecules of NADH are produced in glycolysis?

    A: Two molecules of NADH are produced in glycolysis.

 

  1. Q: What is the function of the electron carriers in cellular respiration

 

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    A: The electron carriers (NADH and FADH2) transport high-energy electrons to the electron transport chain.

 

  1. Q: How does the electron transport chain generate a proton gradient?

    A: The electron transport chain uses energy from electron transfers to pump protons across the inner mitochondrial membrane.

 

  1. Q: What is the primary role of oxygen in cellular respiration?

    A: The primary role of oxygen is to act as the final electron acceptor in the electron transport chain, forming water.

 

  1. Q: What is the role of cytochrome c in the electron transport chain?

    A: Cytochrome c transfers electrons from complex III to complex IV in the electron transport chain.

 

  1. Q: What are the three phases of glycolysis?

    A: The three phases of glycolysis are energy investment, cleavage, and energy generation.

 

  1. Q: How is energy harvested from NADH and FADH2 in the electron transport chain?

    A: Energy from NADH and FADH2 is harvested as electrons pass through the electron transport chain, driving proton pumps.

 

  1. Q: What are the three main stages of cellular respiration?

    A: The three main stages of cellular respiration are glycolysis, the citric acid cycle, and oxidative phosphorylation.

 

  1. Q: What is the role of oxygen in the electron transport chain?

    A: Oxygen acts as the final electron acceptor, combining with electrons and protons to form water.

 

  1. Q: What is the role of Coenzyme Q (CoQ) in the electron transport chain?

    A: Coenzyme Q transfers electrons from complex I and II to complex III in the electron transport chain.

 

  1. Q: What happens to pyruvate in aerobic respiration?

    A: In aerobic respiration, pyruvate enters the mitochondria and is further oxidized in the citric acid cycle.

 

  1. Q: What is the primary function of NADP+ in photosynthesis?

    A: NADP+ is reduced to NADPH during the light-dependent reactions, carrying energy and high-energy electrons to the Calvin cycle.

 

  1. Q: How many turns of the Calvin cycle are needed to produce one molecule of glucose?

    A: Six turns of the Calvin cycle are needed to produce one molecule of glucose.

 

  1. Q: How does the Calvin cycle regenerate RuBP (ribulose-1,5-bisphosphate)?

    A: The last step of the Calvin cycle regenerates RuBP using ATP.

 

  1. Q: What are the products of the Calvin cycle?

    A: The products of the Calvin cycle are G3P (glyceraldehyde 3-phosphate) and ADP.

 

  1. Q: What is the role of stomata in photosynthesis?

    A: Stomata are small pores on plant leaves that allow carbon dioxide to enter for photosynthesis while releasing oxygen and water vapor.

 

  1. Q: What are the three phases of the Calvin cycle?

    A: The three phases of the Calvin cycle are carbon fixation, reduction, and regeneration of RuBP.

 

  1. Q: How is the rate of photosynthesis affected by light intensity?

    A: The rate of photosynthesis increases with increasing light intensity, up to a certain point where it plateaus.

 

  1. Q: What is the role of carotenoids in photosynthesis?

    A: Carotenoids help protect plants from excess light energy by dissipating it as heat.

 

  1. Q: How does temperature affect photosynthesis?

    A: Photosynthesis is temperature-sensitive; it increases with temperature until it reaches an optimum point, beyond which it declines.

 

  1. Q: What is the role of the photosystems in the light-dependent reactions?

    A: Photosystems are pigment-protein complexes that capture light energy and transfer it to reaction centers.

 

  1. Q: What is the primary function of NADP+ in photosynthesis?

    A: NADP+ is reduced to NADPH during the light-dependent reactions, carrying energy and high-energy electrons to the Calvin cycle.

 

  1. Q: How is the energy from the sun captured in photosynthesis?

     A: Energy from the sun is captured by chlorophyll and other pigments in the light-harvesting complexes.

 

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