Photosynthesis

• What is photosynthesis?

  Photosynthesis is the process in which light energy is converted to chemical energy in the form of sugars.
• What are the main products of photosynthesis?

  Glucose molecules and oxygen are produced during photosynthesis.
• What do glucose molecules provide to organisms?

  Glucose molecules provide energy and fixed organic carbon to organisms.
• What is carbon fixation?

  Carbon fixation is the process of incorporating inorganic carbon from carbon dioxide into organic molecules.
• What role do photosynthetic organisms play in ecosystems?

  They introduce chemical energy and fixed carbon into ecosystems by synthesizing sugars.
• What are photoautotrophs?

  Photoautotrophs are organisms that produce their own food using light energy.
• What are heterotrophs?

  Heterotrophs are organisms that cannot convert carbon dioxide to organic compounds themselves.
• How did photosynthesis affect Earth's atmosphere?

  Photosynthesis generated oxygen gas as a byproduct, changing the atmosphere over 3 billion years ago.
• What is the significance of ancient photosynthesizers?

  They gradually released oxygen into Earth's atmosphere, influencing the evolution of aerobic life forms.
• What do photosynthetic organisms do with carbon dioxide?

  They remove carbon dioxide from the atmosphere and use it to build organic molecules.
• Why is preserving forests important in relation to carbon dioxide levels?

  Preserving forests helps combat rising carbon dioxide levels in the atmosphere.
• Where does most photosynthesis take place in plants?

  Most photosynthesis takes place in the leaves of plants.
• What is the mesophyll?

  The mesophyll is the middle layer of leaf tissue where the primary site of photosynthesis occurs.
• What are stomata?

  Stomata are small pores on the surface of leaves that allow gas exchange.
• What are chloroplasts?

  Chloroplasts are organelles in mesophyll cells specialized for photosynthesis.
• What are thylakoids?

  Thylakoids are disc-like structures within chloroplasts that contain chlorophylls.
• What is the stroma in chloroplasts?

  The stroma is the fluid-filled space around the grana in chloroplasts.
• What are the two stages of photosynthesis?

  The two stages of photosynthesis are the light-dependent reactions and the Calvin cycle.
• Where do the light-dependent reactions take place?

  The light-dependent reactions take place in the thylakoid membrane of chloroplasts.
• What is the role of chlorophyll in photosynthesis?

  Chlorophyll absorbs light energy, which is converted into chemical energy.
• What are the products of the light-dependent reactions?

  The products of the light-dependent reactions are ATP and NADPH.
• What is the Calvin cycle?

  The Calvin cycle is the stage of photosynthesis that uses ATP and NADPH to fix carbon dioxide and produce sugars.
• How does ATP contribute to photosynthesis?

  ATP provides energy for the Calvin cycle to fix carbon dioxide into sugars.
• What is the relationship between photosynthesis and cellular respiration?

  Photosynthesis and cellular respiration involve a series of redox reactions and are interconnected processes.
• What is non-cyclic photophosphorylation?

  Non-cyclic photophosphorylation is the process where electrons are removed from water and passed through photosystems to produce ATP and NADPH.
• What happens during light absorption in photosystem II?

  Light absorption in photosystem II boosts an electron to a high energy level, which is then passed to an acceptor molecule.
• What is chemiosmosis in the context of photosynthesis?

  Chemiosmosis is the process where H+ ions flow down their gradient through ATP synthase to produce ATP.
• What is the role of NADPH in photosynthesis?

  NADPH acts as a reduced electron carrier that provides electrons for the Calvin cycle.
• What is cyclic photophosphorylation?

  Cyclic photophosphorylation is a process where electrons follow a circular path and only ATP is produced.
• What are photosystems?

  Photosystems are large complexes of proteins and pigments that harvest light energy in photosynthesis.
• What happens when a pigment absorbs a photon?

  The pigment is raised to an excited state, boosting one of its electrons to a higher-energy orbital.
• What is resonance energy transfer in photosystems?

  Resonance energy transfer is the process where excited pigments pass energy to neighboring pigments in a photosystem.
• What is the reaction center of a photosystem?

  The reaction center contains a unique pair of chlorophyll a molecules that convert absorbed energy into high-energy electrons.
• What are the steps of the light-dependent reactions?

  1. Light absorption in PSII
  2. ATP synthesis via chemiosmosis
  3. Light absorption in PSI
  4. NADPH formation
• What are the main components of a photosystem?

  • Light-harvesting complexes
  • Reaction center with special pair of chlorophyll a molecules
  • Proteins and pigments
• What are the differences between photosystem I and photosystem II?

  • Photosystem I (PSI) has a special pair called P700.
  • Photosystem II (PSII) has a special pair called P680.
• What is the significance of the special pair in a photosystem?

  • The special pair converts absorbed energy into high-energy electrons.
  • It plays a crucial role in the light-dependent reactions.
• How do pigments in a photosystem work together?

  • Pigments act as an energy funnel.
  • They transfer energy to the reaction center through resonance energy transfer.
• What is the overall effect of the light-dependent reactions?

  • Convert light energy into chemical energy.
  • Produce ATP and NADPH for the Calvin cycle.
• What happens to a pigment when it absorbs a photon?

  It is raised to an excited state.