B4 Photosynthesis

• photosynthesis is a chemical reaction carried out by plants and algae
• the equation for photosynthesis is carbon dioxide + water -> glucose + oxygen
• Chlorophyll

  Green pigment stored in structures called chloroplasts. It absorbs light for photosynthesis
• Photosynthesis is an endothermic reaction
• Root hair cells

  Absorb water + minerals

  Large surface area to increase rate of diffusion + osmosis
• Stomata

  Allows CO2 to diffuse in and out

  Creates short diffusion pathway so increase the rate of diffusion
• Variegated leaves

  Green sections of a leaf contain chlorophyll

  Chlorophyll absorbs light for photosynthesis
• How is glucose stored?

  Used in respiration to release energy

  Stored as starch - insoluble

  Used to make cellulose - needed to make cell walls

  Used to make fats, oils, fruits, seeds

  Used to make amino acids which also require nitrates
• Distance and light energy are inversely proportional to each other
• Light intensity ⍺ 1/distance²
• Limiting Factor is a variable that controls the rate of photosynthesis
• What are the four limiting factors of photosynthesis?

  Concentration of Carbon Dioxide

  Light Intensity

  Chlorophyll

  Temperature
• What are the main uses of glucose in plants?

  Respiration

  Makes starch

  Makes amino acids

  Makes fats ,oils ,seeds and fruits

  Makes cellulose
• How does the rate of photosynthesis vary with temperature?

  The rate initially rises because particles have more energy so move faster. The highest rate is the optimum temperature. At higher temperatures the rate decreases as bonds holding the enzyme together begin to break, and so the enzyme changes shape. Rate falls to zero as enzymes denature