Photosynthesis

• What are the raw materials needed for photosynthesis?

  Carbon dioxide and water
• What type of reaction is photosynthesis?

  It is an endothermic reaction
• What is the equation that summarizes photosynthesis?

  6CO₂ + 6H₂O light C₆H₁₂O₆ + 6O₂
• What is the process of photosynthesis?

  • Takes place in chloroplasts
  • Uses light energy to convert CO₂ and H₂O into glucose and O₂
  • Oxygen is released as a by-product
• How do plants obtain the energy needed for photosynthesis?

  They absorb light energy from the environment
• What happens to the glucose produced during photosynthesis?

  Some is used for respiration, and some is converted into starch for storage
• What gas is produced as a by-product of photosynthesis?

  Oxygen
• Why is it difficult to show that oxygen is produced by land plants during photosynthesis?

  Oxygen is a colorless gas and hard to detect
• How can you demonstrate that a water plant is photosynthesizing?

  By collecting bubbles of gas released during the process
• What adaptations do leaves have for photosynthesis?

  • Broad surface area for light absorption
  • Thin structure for short diffusion distance
  • Contain chlorophyll in chloroplasts
  • Air spaces for gas exchange
  • Stomata for gas entry and exit
  • Guard cells to regulate stomata
• What do leaves contain that is essential for photosynthesis?

  Chlorophyll
• Why do leaves have air spaces?

  To allow carbon dioxide to reach mesophyll cells and remove oxygen
• What is the role of guard cells in leaves?

  To open and close stomata for gas exchange
• Why is photosynthesis considered an endothermic reaction?

  It requires energy from the environment to occur
• What are the three main limiting factors affecting the rate of photosynthesis?

  Light intensity, temperature, and carbon dioxide concentration
• How does light intensity affect the rate of photosynthesis?

  Higher light intensity increases the rate of photosynthesis
• What happens to the rate of photosynthesis when temperature rises?

  It increases until enzymes are denatured at high temperatures
• Why is carbon dioxide concentration often a limiting factor for photosynthesis?

  Because the atmosphere contains only about 0.04% carbon dioxide
• What is the relationship between light intensity and distance from the light source?

  Light intensity decreases as the distance from the light source increases
• What is the inverse square law in relation to light intensity?

  Light intensity is inversely proportional to the square of the distance from the light source
• What do plants use glucose for?

  For respiration and to build larger molecules like cellulose
• Why do plants convert glucose into starch for storage?

  Because starch is insoluble and does not affect water balance
• What are the waste products of respiration in plants?

  Carbon dioxide and water
• What are the practical tests for starch, sugars, and proteins?

  • Starch: Iodine test (turns blue-black)
  • Sugars: Benedict's test (turns brick red)
  • Proteins: Biuret test (turns purple)
• Do cells respire all the time?

  Yes, cells respire all the time.
• What are the waste products of respiration?

  Carbon dioxide and water are the waste products.
• What do cells use some of the glucose produced during photosynthesis for?

  Cells use glucose for respiration.
• How is respiration related to photosynthesis chemically?

  Respiration is the reverse of photosynthesis.
• What do plants build from glucose during respiration?

  Plants build larger molecules like complex carbohydrates.
• What is cellulose used for in plants?

  Cellulose is used for strengthening cell walls.
• Why do plants convert some glucose into starch?

  Starch is used for storage in plants.
• Why is glucose stored in solution problematic for plants?

  It could affect the way water moves in and out of cells by osmosis.
• Why is starch advantageous for storage in plants?

  Starch is insoluble and does not affect water balance.
• Where is starch primarily stored in plants?

  Starch is stored in the cells all over the plant.
• What role does starch play in leaves?

  It provides an energy store for when light levels are low.
• How do tubers and bulbs help plants survive winter?

  They store starch to help the plant survive through winter.
• What is the iodine solution test used for?

  It tests for the presence of starch.
• Why must leaves be specially prepared for the iodine test?

  To allow iodine to reach the cells and react with starch.
• What happens to the iodine solution when it reacts with starch?

  Iodine solution turns blue-black in the presence of starch.
• What color does the iodine solution remain on a leaf kept in the dark?

  The iodine solution remains orange.