Cellular respiration and photosynthesis

• Biochemical processes


  Chemical reactions that happen in the cells of living things
• Two important biochemical processes

  • Respiration
  • Photosynthesis
• Metabolism


  The sum of all the chemical reactions in an organism
• Catabolic reactions


  Release energy and break large molecules down into smaller molecules
• Anabolic reactions


  Require energy and build large molecules from smaller ones
• Activities that require energy

  • Running
  • Walking
  • Sleeping
  • Talking
  • Thinking
• Respiration


  The release of energy from food
• Mitochondria


  Tiny organelles in the cytoplasm of a cell where respiration takes place
• Aerobic respiration


  Respiration that takes place in the presence of oxygen
• Requirements for aerobic respiration

  • Glucose
  • Oxygen
• Anaerobic respiration


  Respiration that takes place in the absence of oxygen
• If a person consumes more energy than they need

  The excess energy will be stored in the body as fat
• Fermentation


  Anaerobic respiration in yeast cells that produces carbon dioxide, causing bread dough to rise
• Factors that affect respiration

  • Temperature
  • Water
  • pH
• Enzymes


  Proteins produced inside cells that control the rate of chemical reactions
• Enzymes are sometimes called 'biological catalysts'
• Water is important during exercise for chemical reactions, muscle contraction, nerve impulse transmission, and removing toxic waste
• How temperature affects the rate of respiration


  Experimental Investigation 11.1
• Photosynthesis


  The biochemical process where plants absorb energy from the Sun to make their own food
• Chloroplasts


  Small organelles in the cytoplasm of plant cells where the reactions of photosynthesis take place
• Chlorophyll


  A green pigment in the chloroplast that absorbs light energy and uses it to power chemical reactions
• Stomata


  Pores in leaves through which oxygen is released as a waste product of photosynthesis
• Oxygen released by photosynthesis is used by organisms for aerobic respiration
• Factors that affect photosynthesis

  • Light intensity
  • Carbon dioxide concentration
  • Temperature
  • Water availability
• Light intensity is an important factor controlling the rate of photosynthesis
• Leaf adaptations to absorb light for photosynthesis

  • Large surface area
  • Thin cross section
  • Presence of stomata
• How light intensity affects the rate of photosynthesis


  Experimental Investigation 11.2
• Respiration and photosynthesis are almost the reverse of one another


  The reactants for respiration are the products of photosynthesis, and the products of respiration are the reactants for photosynthesis
• Respiration and photosynthesis as chemical processes


  A series of steps are involved, reactants are used, products are made, and energy is transformed
• Respiration and photosynthesis as biological processes

  Reactions take place in cells and enzymes play a role in controlling the rate of both processes
• Key terms


  • Biochemical processes
  • Respiration
  • Mitochondria
  • Aerobic respiration
  • Anaerobic respiration
  • Photosynthesis
  • Chloroplasts
  • Chlorophyll