Photosynthesis and respiration

• Photosynthesis


  A chemical reaction where energy is transferred from the environment as light from the Sun to the leaves of a plant. This is an endothermic reaction.
• Chlorophyll


  • The green pigment in chloroplasts in the leaves that absorbs the light energy
  • Leaves are well-adapted to increase the rate of photosynthesis when needed
• Limiting factor


  Anything that limits the rate of a reaction when it is in short supply
• Limiting factors for photosynthesis

  • Temperature
  • Carbon dioxide concentration
  • Light intensity
  • Amount of chlorophyll
• Less chlorophyll in the leaves

  Reduces the rate of photosynthesis
• More chlorophyll produced by plants in well-lit areas


  Increases the rate of photosynthesis
• Uses of glucose from photosynthesis


  • Converted into insoluble starch for storage
  • For respiration to release energy
  • Produce cellulose to strengthen cell walls
  • Produce fat or oil (lipids) for storage
  • Produce amino acids for protein synthesis
• At low temperatures


  The rate of photosynthesis is low because the reactant molecules have less kinetic energy
• At high temperatures


  The enzymes are denatured and the rate of photosynthesis quickly decreases
• Increasing carbon dioxide concentration

  Increases the rate of photosynthesis
• Increasing light intensity


  Increases the rate of photosynthesis
• Photosynthesis will stop if there is little or no light
• Cellular respiration


  An exothermic reaction that occurs continuously in the mitochondria of living cells to supply the cells with energy
• Processes that require the energy released during respiration

  • Chemical reactions to build larger molecules, for example, making proteins from amino acids
  • Muscle contraction for movement
  • Keeping warm
• Aerobic respiration


  Uses the complete oxidation of glucose to release a large amount of energy
• Anaerobic respiration


  Uses the incomplete oxidation of glucose and releases much less energy per glucose molecule than aerobic respiration
• Aerobic respiration


  Glucose + Oxygen → Carbon dioxide + Water
• Anaerobic respiration in muscles

  Glucose → Lactic acid
• Metabolism


  The sum of all the reactions in a cell or the body. The energy released by respiration in cells is used for the continual enzyme-controlled processes of metabolism that produce new molecules.
• Metabolic processes


  • Synthesis and breakdown of carbohydrates, proteins, and lipids
• Anaerobic respiration in plant and yeast cells

  Glucose → Ethanol + Carbon dioxide
• During exercise with insufficient oxygen

  Anaerobic respiration takes place, leading to the build-up of lactic acid
• During long periods of vigorous exercise

  Muscles become fatigued and stop contracting efficiently
• Removal of lactic acid


  Lactic acid in the muscles is transported to the liver in the blood and converted back to glucose
• Antibodies have to be the right shape for a pathogen's unique antigens, so they target a specific pathogen