photosynthesis

• What are the raw materials for photosynthesis?

  Carbon dioxide (CO₂) and water (H₂O)
• What are the products of photosynthesis?

  Glucose (C₆H₁₂O₆) and oxygen (O₂)
• Why is chlorophyll important for photosynthesis?


  It absorbs light energy necessary for the process
• What are the rate limiting factors of photosynthesis?

  Carbon dioxide concentration, light intensity, and temperature
• What is the role of ATP in photosynthesis?

  It provides energy for cellular processes
• What adaptations do leaves have for efficient photosynthesis?

  • Large surface area to absorb sunlight
  • Thin structure for short diffusion distance
  • Transparent cuticle and epidermis for light penetration
  • Long, narrow upper mesophyll cells packed with chloroplasts
  • Network of xylem for water transport
  • Phloem for transporting sugars
• Where do the light-dependent reactions occur in the chloroplasts?

  In the grana
• What happens during the light-dependent reactions?

  Light energy is absorbed and used for ATP synthesis, NADP reduction, and photolysis of water
• What stops the light-dependent reactions from occurring?

  Absence of light
• Where do the light-independent reactions occur in the chloroplasts?

  In the stroma
• What is the role of rubisco in photosynthesis?

  It catalyzes the reaction of carbon dioxide with ribulose bisphosphate
• How does ATP contribute to the light-independent reactions?

  It provides energy for regenerating ribulose bisphosphate (RuBP)
• What is the function of NADPH in the light-independent reactions?

  It provides hydrogen for building molecules needed to recycle RuBP
• What are the stages of photosynthesis?

  1. Light-dependent reactions:

  • Occur in the grana
  • Produce ATP and NADPH
  • Require light

  1. Light-independent reactions (Calvin cycle):

  • Occur in the stroma
  • Use ATP and NADPH
  • Do not directly require light
• What is photoionisation in photosynthesis?

  It is the process where light absorption by chlorophyll emits an electron
• What is chemiosmosis in the context of photosynthesis?

  It is the process where protons diffuse out of the thylakoid space to synthesize ATP
• What are the adaptations of chloroplasts for photosynthesis?

  • Many grana for large surface area
  • Many thylakoid membranes for oxidation and reduction reactions
  • Many ATP synthase enzymes in thylakoid membranes
  • DNA and ribosomes for protein synthesis
• How does carbon dioxide enter the leaf for photosynthesis?

  It diffuses through stomata into mesophyll cells
• What is carbon fixation in photosynthesis?

  It is the process where carbon dioxide is fixed onto ribulose bisphosphate to form a larger organic molecule
• What happens to the Calvin cycle when a plant is placed in darkness?

  It stops shortly after due to lack of ATP and NADPH
• How do oxidation and reduction relate to photosynthesis?

  Oxidation involves loss of electrons, while reduction involves gain of electrons during the reactions
• What is the role of glycerate-3-phosphate (GP) in photosynthesis?

  Some GP is used to make glucose, and some is recycled to regenerate RuBP
• What is the function of phloem in leaves?

  It carries away the sugars produced during photosynthesis
• What is the function of xylem in leaves?

  It brings water to the leaf cells
• Where do the light-dependent reactions of photosynthesis occur?

  Thylakoid membrane
• What is the fluid part in the center of the chloroplast called?

  Stroma
• What are the two main stages of photosynthesis?

  Light-dependent and light-independent reactions
• Why is the light-dependent reaction called so?

  It requires light energy to occur
• What are the four key steps in the light-dependent reactions?

  Photolysis, photoionization, chemiosmosis, ATP and NADPH production
• What happens during photolysis in the light-dependent reactions?

  Water is split into oxygen, electrons, and protons
• What is the role of NADP in the light-dependent reactions?

  It picks up protons to form NADPH
• What happens during photoionization of chlorophyll?

  Electrons gain energy and leave the chlorophyll
• How is ATP produced in the light-dependent reactions?

  Protons move through ATP synthase, phosphorylating ADP
• Where do the light-independent reactions (Calvin cycle) occur?

  Stroma
• What enzyme is crucial in the Calvin cycle?

  Rubisco
• Why is the Calvin cycle temperature-sensitive?

  It involves enzymes like Rubisco
• What are the products of the light-dependent reactions used in the Calvin cycle?

  ATP and NADPH
• What happens to carbon dioxide in the Calvin cycle?

  It reacts with RuBP to form GP
• How many times must the Calvin cycle occur to produce one hexose sugar?

  Six times
• What are the possible uses of the hexose sugar produced in the Calvin cycle?

  Cellulose, starch, lipids, amino acids