Oxygen competitively inhibits this enzyme’s active site, leading to a side reaction that produces the toxic compound 2-phosphoglycolate. For 10 points each:
[10m] Name this most abundant enzyme on Earth. This enzyme fixes carbon dioxide to a ribulose derivative during the Calvin cycle.
ANSWER: RuBisCO (“roo-BISS-ko”) [or ribulose-1,5-bisphosphate carboxylase-oxygenase or RuBPCase or RuBPco]
[10h] To mitigate oxygen inhibition, some plants use this pathway in which the Calvin cycle is sequestered in bundle-sheath cells. In this pathway, carbon dioxide is fixed to produce malate or aspartate in mesophyll cells.
ANSWER: C4 photosynthesis [or C4 carbon fixation or Hatch-Slack pathway; reject “C3 photosynthesis”]
[10e] RuBisCO is tethered by carboxysomes in photosynthetic organisms from this taxonomical domain that may have caused the Great Oxygenation Event. The three-domain system includes Archaea, Eukarya, and this domain.
ANSWER: Bacteria [accept cyanobacteria; reject “algae”]
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