Plant transport

• Glucose

  Condensed to sucrose to be transported through phloem
• Glucose


  Stored as starch
• Cellulose

  In cell wall
• Nitrogen

  Amino acids, proteins
• Respiration

  Release energy (break down of glucose)
• Photosynthesis

  1. 6CO2 + 6H2O → C6H12O6 + 6O2

  2. Light energy trapped by chlorophyll in the chloroplast
• Photosynthesis

  The process by which the plant makes carbohydrates (glucose/organic compound) from carbon dioxide and water (inorganic compounds) using light energy
• Respiration


  Release energy (break down of glucose) used in active transport, cell division, movement, part of this energy is heat energy to keep body temperature constant
• Plant nutrition

  Photosynthesis (involves production of glucose) condensation/anabolic/building up using light energy converted into chemical energy stored in glucose
• Glucose produced in leaf from photosynthesis
• Sucrose

  Less reactive, transported through phloem
• Glucose fate

  1. Respiration

  2. Cellulose cell wall

  3. Stored as starch

  4. React with nitrogen to form amino acids, proteins
• Importance of glucose to plant

  • Condensed into sucrose for transport
  • Used in respiration
  • Used to make cellulose in cell wall
  • Stored as starch
  • React with nitrogen to form amino acids and proteins
• Balanced equation of photosynthesis: 6CO2 + 6H2O → C6H12O6 + 6O2
• Word equation for photosynthesis: Carbon dioxide + Water → Glucose + Oxygen
• Role of Upper epidermis in photosynthesis

  Transparent to allow light to pass through to reach the chlorophyll in chloroplast in the mesophyll cells
• Upper epidermis

  • Transparent to allow light
  • Protective layer to prevent entry of pathogens/microorganisms
  • Produce waxy cuticle to reduce water loss
• Palisade mesophyll

  • Packed with many chloroplasts for maximum absorption of light energy
  • Cells are arranged close together with tiny air spaces to absorb more light energy
  • Arranged in columns, ends on to allow light to pass through with minimum number of cell walls
• Spongy mesophyll

  Allow diffusion of gases through their air spaces
• Spongy mesophyll

  • Loosely packed with large air spaces to allow diffusion of gases
  • Mesophyll cells surrounded by film of water/water droplets that evaporate into air spaces, helping to dissolve gases and cool down the plant by transpiration
• Xylem

  Transport water and minerals
• Phloem

  Transport sucrose and amino acids
• Stomata

  • Allow exchange of gases by allowing diffusion of carbon dioxide into the leaf for photosynthesis and oxygen out for respiration
  • Allow diffusion of water vapour out of the leaf in transpiration to help cool down the plant
• Guard cells


  Control the opening and closing of stomata
• Shortage of water (high temperature)

  Guard cells become flaccid, stomata close to reduce water loss by transpiration
• Increase in light intensity, plenty of water

  Guard cells become turgid, stomata open to allow diffusion of CO2 into the leaf for photosynthesis
• Ion concentration in guard cells

  Increase, decreasing water potential inside the cell compared to outside, causing water to move into guard cells by osmosis, increasing their volume and opening the stomata
• Limiting factors for photosynthesis

  Carbon dioxide concentration, light intensity, temperature
• Carbon dioxide concentration

  Increasing it increases the rate of photosynthesis and crop yield
• Light

  Source of energy, absorbed by chlorophyll, converted into chemical energy stored in glucose
• Carbon dioxide

  Reactant, limiting factor for photosynthesis
• Substrate concentration


  Rate of reaction
• Substrate concentration was a limiting factor


  Present in short supply
• Substrate is found in excess

  No longer a limiting factor
• Enzyme

  Limiting factor
• Pocket money

  Expenses
• Pocket money is limiting factor

  Pocket money is no longer
• Limiting factors for photosynthesis

  • Light intensity
  • CO2 concentration
  • Temperature
• Light intensity is a limiting factor


  Rate of photosynthesis
• Light is no longer a limiting factor

  CO2 concentration or temperature is a limiting factor