L34: Glycogen

• What is the primary source of free energy for biological systems?

  Solar energy trapped by photosynthesis
• How much free energy does photosynthesis store globally each year?

  About $10^{18} \text{ kJ}$
• What is the waste product of photosynthesis?

  Oxygen
• How many tons of carbon are fixed into carbohydrates and other organic compounds by photosynthesis each year?

  About 200 billion tons
• What role do stomata play in photosynthesis?

  They allow the exchange of air, including $H_2O$ and $CO_2$
• What are the two main stages of photosynthesis?

  Light-dependent reactions and light-independent reactions
• What occurs during the light-dependent reactions of photosynthesis?

  • Capture of photons
  • Conversion of light energy to ATP and NADPH
• What occurs during the light-independent reactions of photosynthesis?

  • Fixing or capturing of $CO_2$
  • Making larger molecules for transport or storage
• What is the key step in capturing energy during photosynthesis?

  Capture of photons
• Which type of light has more energy, blue or red?

  Blue light has more energy than red light
• What is Planck's constant?

  6.6 \times 10^{-34} \text{ J·s}
• How does the energy of a photon relate to its wavelength?

  The energy of a photon is inversely proportional to its wavelength
• What does the Hill reaction demonstrate in photosynthesis?

  It shows that the primary event in photosynthesis is the light-driven transfer of an electron
• What is the role of the light harvesting complex in photosynthesis?

  It captures photons and transfers energy to the reaction center
• What happens to the excited electron in the reaction center?

  It can be transferred to other molecules in a series of redox reactions
• What is the "red drop" phenomenon in photosynthesis?

  It refers to the increase in wavelength and decrease in energy affecting photosynthetic rates
• What is the terminal electron acceptor in the light-dependent reactions?

  NADP⁺
• What does the Z Scheme illustrate in photosynthesis?

  It illustrates the changes in redox potential during the light-dependent reactions
• What is unique about the enzyme in Photosystem II?

  It is the only enzyme in nature able to split water
• Why is Rubisco considered a disappointing enzyme?

  It has slow catalytic activity and is not efficient at distinguishing between O₂ and CO₂
• How do C4 plants avoid photorespiration?

  They concentrate CO₂ at the site of the Calvin cycle
• What are the two types of carbohydrates produced during photosynthesis?

  Sucrose (mobile) and starch (storage)
• What is the overall efficiency of photosynthesis?

  About 30%
• What are the main differences between light and dark reactions in photosynthesis?

  • Light reactions:
  • Light harvesting
  • Produce NADPH and ATP
  • Cyclic or Z scheme
  • Dark reactions:
  • Calvin cycle
  • Interaction with gluconeogenesis and PPP pathways