AS and A Level Biology 3 Views 1 Answers
State that within a chloroplast, the thylakoids (thylakoid membranes and thylakoid spaces), which occur in stacks called grana, are the site of the light-dependent stage and the stroma is the site of the light-independent stage
State that within a chloroplast, the thylakoids (thylakoid membranes and thylakoid spaces), which occur in stacks called grana, are the site of the light-dependent stage and the stroma is the site of the light-independent stage
Answer
Chloroplast Structure and Photosynthetic Stages
Within a chloroplast, distinct regions facilitate the two stages of photosynthesis:
- Light-Dependent Stage (Light Reactions):
- Location: Thylakoids (Thylakoid Membranes and Thylakoid Spaces)
- Arrangement: Stacks called Grana
- Processes:
- Light absorption by pigments (e.g., chlorophyll)
- Exciton transfer and electron transport
- ATP and NADPH synthesis (via photophosphorylation)
- Light-Independent Stage (Calvin Cycle):
- Location: Stroma
- Processes:
- CO2 fixation (via RuBisCO)
- Reduction of fixed CO2 to glucose (using ATP and NADPH from the Light-Dependent Stage)
Key Points from the Provided Web Search Results:
- Thylakoids/Grana:
- Disc-shaped structures stacked in grana (singular: granum)
- Contain chlorophyll and are the site of light-dependent reactions
- Thylakoid membrane envelops the thylakoid lumen
- Stroma:
- Protein-rich, alkaline, aqueous fluid surrounding the grana
- Equivalent in function to the mitochondrial matrix
- Site of the chloroplast genetic system and metabolic enzymes, including those for CO2 conversion to carbohydrates
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