Bioenergetics

• What does photosynthesis produce using light?

  Glucose and oxygen
• Where does photosynthesis take place in plants?

  In chloroplasts of green plant cells
• What role do chlorophyll pigments play in photosynthesis?

  They absorb light energy
• How is energy transferred to chloroplasts?

  By light from the environment
• What type of reaction is photosynthesis?

  Endothermic
• What is the word equation for photosynthesis?

  Light + carbon dioxide + water → glucose + oxygen
• What is the symbol equation for photosynthesis?

  6CO₂ + 6H₂O → C₆H₁₂O₆ + 6O₂
• What are the five main ways plants use glucose?

  • For respiration
  • Making cellulose
  • Making amino acids
  • Stored as oils or fats
  • Stored as starch
• How do plants use glucose for respiration?

  It transfers energy from glucose
• How are amino acids made in plants?

  By combining glucose with nitrate ions
• What is cellulose made from?

  Glucose converted into cellulose
• Why do plants store glucose as starch?

  Starch is insoluble and better for storage
• What factors affect the rate of photosynthesis?

  Light intensity, CO₂ concentration, and temperature
• What does it mean if a factor is a limiting factor in photosynthesis?

  It stops photosynthesis from happening faster
• What is the limiting factor at night?

  Light
• What is often the limiting factor in winter?

  Temperature
• What can be a limiting factor if conditions are warm and bright?

  CO₂ concentration
• How can chlorophyll be a limiting factor?

  It can be affected by disease or nutrient stress
• What happens to chloroplasts if a plant is diseased?

  They may become damaged or produce less chlorophyll
• What happens to the rate of photosynthesis if chlorophyll levels are low?

  The rate of photosynthesis is reduced
• What does light provide for photosynthesis?

  The energy needed for the process
• What happens to the rate of photosynthesis as light intensity increases?

  It increases steadily up to a point
• What occurs beyond the point of maximum light intensity?

  The rate of photosynthesis no longer increases
• How can light intensity be changed in a lab experiment?

  By moving a lamp closer or further away
• What is the shape of the graph when plotting rate of photosynthesis against distance of lamp?

  It is a weird-shaped graph
• What happens to the rate of photosynthesis if CO₂ levels are too low?

  It slows down
• What happens to the rate of photosynthesis when CO₂ is plentiful?

  Temperature becomes the limiting factor
• What happens to enzymes at low temperatures?

  They work more slowly
• What happens to enzymes if the temperature is too high?

  They get damaged
• At what temperature do enzymes start to get damaged?

  About 45 °C
• How can multiple limiting factors affect the rate of photosynthesis?

  • Light intensity and temperature can both limit photosynthesis.
  • The rate increases linearly until a limiting factor is reached.
  • Different factors can limit photosynthesis at different times.
• What does a graph showing light intensity and temperature indicate?

  Both factors affect the rate of photosynthesis
• What does a graph showing light intensity and CO₂ concentration indicate?

  Both factors affect the rate of photosynthesis
• How can Canadian pondweed be used in experiments?

  To measure the effect of light intensity on photosynthesis
• What does the rate of oxygen production indicate in pondweed experiments?

  It corresponds to the rate of photosynthesis
• What is the first step in the pondweed experiment?

  Place a light source at a specific distance
• How is the volume of oxygen produced measured in the pondweed experiment?

  By measuring the length of the gas bubble
• What should be controlled in the pondweed experiment?

  Temperature and time of photosynthesis
• What can be done to measure the effect of temperature on photosynthesis?

  Use a water bath at a set temperature
• What can be done to measure the effect of CO₂ on photosynthesis?

  Add sodium hydrogencarbonate to the water