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General Biology: Enzyme Function, Cellular Respiration, and Photosynthesis

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  • What is allosteric inhibition in enzymes?
    A product binds to a site other than the active site, changing the active site's shape and decreasing substrate binding.
  • What type of inhibition do NSAIDs like Vioxx exhibit on COX-2 enzyme?
    They are competitive inhibitors, as high substrate concentrations reduce their efficacy.
  • How does ethyl alcohol act as an antidote for methyl alcohol poisoning?
    Ethyl alcohol competitively inhibits alcohol dehydrogenase by blocking its active site, preventing methyl alcohol breakdown.
  • What type of inhibition do sulfa antibiotics demonstrate?
    Competitive inhibition by occupying the active site and blocking the normal substrate.
  • How does an acidic environment affect bacterial enzymes?
    It causes bacterial enzymes to fail or work less efficiently.
  • What type of inhibitor is triclosan with respect to sulfotransferase enzyme?
    Triclosan is a competitive inhibitor, resembling the substrate and binding the active site.
  • What role does oxygen play in cellular respiration?
    Oxygen accepts electrons at the end of the electron transport chain.
  • Which molecule collects most electrons from food during cellular respiration?
    NAD+ collects the majority of electrons.
  • Which cellular respiration process is NOT inhibited by cyanide binding to cytochrome oxidase IV?
    The reduction of NAD+ and FAD is not inhibited.
  • How many pyruvate molecules are produced from one glucose molecule during cellular respiration?
    Two pyruvate molecules are generated.
  • Why does stealing electrons from FADH2 and NADH kill insects?
    It prevents the electron transport chain from establishing a proton gradient, reducing ATP production.
  • What kind of poison directly interferes with glycolysis?
    An agent that mimics glucose structure but is not metabolized.
  • How does abundant ATP affect the citric acid cycle?
    ATP binds allosterically to slow the enzyme combining acetyl CoA and oxaloacetate, reducing the cycle rate.
  • What happens to acetyl groups from beta-oxidation of fatty acids?
    They directly enter the citric acid cycle.
  • Where does glycolysis occur in the cell?
    Glycolysis occurs in the cytoplasm.
  • What is the energy source driving ATP synthase in mitochondria?
    H+ ions flowing across the mitochondrial inner membrane.
  • What are the three main products of glycolysis?
    ATP, NADH, and pyruvic acid.
  • Where are the enzymes of the electron transport chain located?
    In the inner membrane of the mitochondrion.
  • Why do plants need two photosystems (PSI and PSII)?
    One photosystem alone cannot provide enough energy to reduce NADP+ and produce ATP.
  • What explains why chloroplasts and mitochondria generate ATP using different energy sources?
    Chloroplasts convert solar energy into chemical energy; mitochondria release stored chemical energy.
  • Why does oxygen production stop if Photosystem II is damaged but Photosystem I functions?
    Oxygen is generated only when water is split in Photosystem II.
  • What is the primary anabolic part of photosynthesis?
    Converting CO2 into glucose during the Calvin cycle.
  • Which light wavelengths result in the highest ATP production during photosynthesis?
    Light wavelengths around 450-500 nanometers (blue light) produce the highest ATP rates.
  • What color of light is reflected by a red leaf?
    Red light is reflected.
  • Where is chlorophyll found in plant cells?
    Chlorophyll is located in the thylakoid membranes.
  • What function does sunlight perform in photosynthesis?
    Sunlight excites electrons in chlorophyll to a higher energy level.
  • What happens if a herbicide blocks electron transfer at photosystems II and I?
    Oxygen production decreases and NADPH formation is reduced.
  • What process is inhibited if the proton gradient across the thylakoid membrane is prevented?
    ATP synthesis by ATP synthase is inhibited.
  • Why are stomata essential for photosynthesis despite water loss?
    They allow CO2 to enter, which is necessary for the Calvin cycle.