energy for biological processes

• What is photosynthesis?

  Photosynthesis is a reaction where light energy splits water to produce glucose and oxygen.
• What is the role of photolysis in photosynthesis?

  Photolysis splits water molecules to release hydrogen for glucose production.
• What are the waste products of photosynthesis?

  Oxygen is a waste product of photosynthesis.
• What factors determine the rate of photosynthesis?

  The rate of photosynthesis is determined by carbon dioxide concentration, light intensity, and temperature.
• How is the chloroplast adapted for photosynthesis?

  • Contains stacks of thylakoid membranes called grana
  • Grana hold photosynthetic pigments like chlorophyll
  • Stroma surrounds grana and contains enzymes for the light-independent stage

  
• What are the two stages of photosynthesis?

  The two stages are the light-dependent reaction and the light-independent reaction (Calvin cycle).
• What happens during the light-dependent reaction of photosynthesis?

  Electrons are excited by light energy, passed down the electron transport chain, generating ATP and reduced NADP.
• What is photophosphorylation?

  Photophosphorylation is the process of generating ATP from ADP and inorganic phosphate during the light-dependent reaction.
• What is the Calvin cycle?

  The Calvin cycle is the light-independent reaction that uses ATP and reduced NADP to produce glucose.
• What are the steps of the Calvin cycle?

  1. RuBP combines with carbon dioxide (carbon fixation)
  2. RuBP converts into two glycerate 3-phosphate (GP) molecules
  3. GP is converted to triose phosphate (TP) using reduced NADP and ATP
  4. Some TP is used to make glucose; others reform RuBP with ATP
• What is a limiting factor in photosynthesis?

  A limiting factor is the component in lowest supply that restricts the rate of photosynthesis.
• How does light intensity affect photosynthesis?

  If light intensity is low, the light-dependent reaction slows, reducing ATP and NADPH production.
• What happens to GP and TP levels when light intensity is low?

  GP levels rise and TP levels fall when light intensity is low.
• How does temperature affect photosynthesis?

  Low temperatures reduce the kinetic energy of Rubisco and other molecules, affecting enzyme-controlled reactions.
• What is aerobic respiration?

  Aerobic respiration is the process of splitting a respiratory substrate to release carbon dioxide and produce energy in the presence of oxygen.
• What is the difference between aerobic and anaerobic respiration?

  Aerobic respiration occurs in the presence of oxygen, while anaerobic respiration occurs in its absence.
• Where does glycolysis occur?

  Glycolysis occurs in the cytoplasm.
• What are the products of glycolysis?

  Glycolysis produces 2 molecules of pyruvate, 2 molecules of NADH, and a net production of 2 molecules of ATP.
• What happens during the link reaction in aerobic respiration?

  Each pyruvate is converted to acetyl, producing NADH and releasing CO2.

  
• What is the Krebs cycle?

  The Krebs cycle is where glucose is oxidized to produce carbon dioxide, ATP, reduced NAD, and reduced FAD.

  
• What are the products of the Krebs cycle per glucose molecule?

  • 4 CO2
  • 4 NADH
  • 2 FADH
  • 2 ATP

  
• What is oxidative phosphorylation?

  Oxidative phosphorylation is the process of synthesizing ATP in the electron transport chain in mitochondria.

  
• How do reduced coenzymes function in oxidative phosphorylation?

  Reduced coenzymes carry hydrogen ions and electrons to the electron transport chain.
• What is the role of hydrogen ions in oxidative phosphorylation?

  Hydrogen ions move across the inner membrane, creating a concentration gradient that drives ATP production.

  
• What is the theoretical yield of ATP per glucose molecule in aerobic respiration?

  The theoretical yield is 38 ATP molecules per glucose molecule.
• Why is the actual yield of ATP lower than the theoretical yield?

  The actual yield is lower due to the inner mitochondrial membrane being 'leaky' to H+ ions.
• What are respiratory substrates?

  Respiratory substrates include carbohydrates, lipids, and proteins that release energy when oxidized.
• How is the respiratory quotient (RQ) calculated?

  RQ is calculated as carbon dioxide produced divided by oxygen consumed.
• What are the RQ values for carbohydrates, lipids, and proteins?

  Carbohydrates have an RQ of 1.0, lipids 0.8, and proteins 0.9.
• What occurs during anaerobic respiration?

  Anaerobic respiration occurs when oxygen is low, allowing glycolysis to continue without oxidative phosphorylation.
• What happens to pyruvate in mammals during anaerobic respiration?

  In mammals, pyruvate is converted to lactate, allowing NADH to be reoxidized to NAD.

  
• How does yeast perform anaerobic respiration?

  Yeast performs alcoholic fermentation, converting pyruvate to ethanol and releasing CO2.

  
• What is the significance of the first step in alcoholic fermentation?

  The first step produces CO2 and is irreversible in the process of converting pyruvate to ethanol.