The same germinating-seed respirometer was used at 25 deg C, but seeds were poisoned with KCN (a cytochrome c oxidase inhibitor) in one trial and untreated in the other.
Why does KCN nearly eliminate O2 consumption?
- A
KCN inhibits glycolysis.
- Bcheck_circle
Cytochrome c oxidase passes electrons to O2; blocking it halts the entire ETC.
- C
KCN dissolves the mitochondrial outer membrane.
- D
KCN replaces O2 as the terminal electron acceptor.
Explanation
Complex IV (cytochrome c oxidase) is the only enzyme that reduces O2 to water in the ETC. Blocking it stops all electron flow and O2 consumption.