EduNinjaAerobic respiration occurs when oxygen is available. A much greater energy yield is obtained from aerobic respiration than from respiration in anaerobic conditions.
Explain why the link reaction only occurs when oxygen is available.
In an investigation, mammalian liver cells were homogenised (broken up) and the resulting homogenate centrifuged. Samples of the complete homogenate and samples containing only nuclei, only ribosomes, only mitochondria or only the remaining cytosol were incubated with:
1 glucose
2 pyruvate
3 glucose and cyanide
4 pyruvate and cyanide
Cyanide inhibits oxidative phosphorylation.
After incubation the presence or absence of carbon dioxide and lactate in each sample was determined.
The results are summarised in Table 7.1.
Table 7.1
Explain why carbon dioxide is produced when mitochondria are incubated with pyruvate but not when they are incubated with glucose.