energy for biological processes

Cards (11)

  • Photosynthesis is a reaction where light energy is used to split water molecules through photolysis to combine hydrogen with carbon dioxide to produce glucose
  • Oxygen is a waste product of photosynthesis and is released into the atmosphere
  • The rate of photosynthesis is determined by carbon dioxide concentration, light intensity, and temperature
  • Chloroplast is the site of photosynthesis and is adapted with stacks of thylakoid membranes called grana containing chlorophyll and stroma containing enzymes for the light-independent stage
  • Two stages of photosynthesis:
    • Light-dependent reaction: electrons are excited by chlorophyll in thylakoid membranes, generating ATP and reduced NADP
    • Light-independent reaction (Calvin cycle): uses ATP and reduced NADP to produce glucose
  • Factors affecting photosynthesis:
    • Light intensity
    • CO2 concentration
    • Temperature
  • Respiration:
    • Aerobic respiration: releases carbon dioxide and reunites hydrogen with oxygen to produce energy
    • Anaerobic respiration: occurs without oxygen
    • Glycolysis is the first step, producing pyruvate, NADH, and ATP
  • Link reaction: converts pyruvate to acetyl, reducing NAD to NADH and producing CO2
    • Krebs cycle: oxidises glucose to produce CO2, ATP, reduced NAD, and reduced FAD
  • Oxidative phosphorylation:
    • ATP synthesis in the electron transport chain in mitochondria
    • Hydrogen ions and electrons carried by coenzymes to generate ATP
    • Oxygen acts as the final electron acceptor
  • Respiratory substrates include carbohydrates, lipids, and proteins
    • Respiratory quotient (RQ) can determine the respiratory substrate being used
    • Different RQ values for carbohydrates, lipids, and proteins
  • Anaerobic respiration:
    • ATP production continues through glycolysis
    • In mammals, pyruvate is converted to lactate
    • Yeast and plants use alcoholic fermentation to enable glycolysis to continue