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Photosynthesis Basics - General Biology

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  • What is photosynthesis?

    Photosynthesis is the process by which green plants, algae, and some bacteria convert light energy into chemical energy stored in glucose.

  • Where does photosynthesis occur in plant cells?

    Photosynthesis occurs in the chloroplasts of plant cells.

  • What are the two main stages of photosynthesis?

    The two main stages are the light-dependent reactions and the Calvin cycle (light-independent reactions).

  • What is the primary pigment involved in photosynthesis?

    Chlorophyll is the primary pigment that absorbs light energy for photosynthesis.

  • What are the main inputs of the light-dependent reactions?

    Light energy, water (H2O), NADP+, and ADP + Pi are the main inputs.

  • What are the main outputs of the light-dependent reactions?

    Oxygen (O2), ATP, and NADPH are produced in the light-dependent reactions.

  • What happens to water during photosynthesis?

    Water is split (photolysis) to release oxygen, electrons, and protons during the light-dependent reactions.

  • What is the role of ATP and NADPH in photosynthesis?

    ATP and NADPH provide energy and reducing power for the Calvin cycle to synthesize glucose.

  • What is the Calvin cycle?

    The Calvin cycle is the light-independent stage where CO2 is fixed into glucose using ATP and NADPH.

  • What enzyme fixes carbon dioxide in the Calvin cycle?

    Rubisco is the enzyme that catalyzes CO2 fixation in the Calvin cycle.

  • What is the overall chemical equation for photosynthesis?

    6 CO2 + 6 H2O + light energy → C6H12O6 + 6 O2

  • Why is photosynthesis important for life on Earth?

    Photosynthesis produces oxygen and organic molecules that are essential for most life forms.

  • What wavelengths of light are most effective for photosynthesis?

    Blue and red wavelengths are most effectively absorbed by chlorophyll for photosynthesis.

  • What is photophosphorylation?

    Photophosphorylation is the process of generating ATP from ADP and Pi using light energy during the light-dependent reactions.

  • What is the role of the electron transport chain in photosynthesis?

    The electron transport chain transfers electrons to produce ATP and NADPH during the light-dependent reactions.

  • What is the source of oxygen released in photosynthesis?

    Oxygen is released from the splitting of water molecules during the light-dependent reactions.

  • How does the Calvin cycle regenerate its starting molecule?

    The Calvin cycle regenerates ribulose bisphosphate (RuBP) to continue fixing CO2.

  • What is the significance of NADP+ in photosynthesis?

    NADP+ acts as an electron carrier, becoming NADPH after accepting electrons in the light-dependent reactions.

  • What is the difference between C3 and C4 photosynthesis?

    C3 plants fix CO2 directly via the Calvin cycle; C4 plants use a separate pathway to concentrate CO2 and reduce photorespiration.

  • How does light intensity affect photosynthesis?

    Increasing light intensity increases the rate of photosynthesis up to a point, after which it plateaus.