Anaerobic Respiration & Energy Budgets

Question 1

Anaerobic Respiration

Answer 1

Occurs in the absence of oxygen

Without oxygen to act as the final electron acceptor, biochemical reactions inside the mitochondria grind to a halt as any reduced NAD and FAD cannot be deoxidised to pick up more hydrogen

A mechanism in glycolysis allows reduced NAD to transfer hydrogen to pyruvate, allowing NAD to again accept hydrogen from glucose.

Glycolysis can proceed giving a net yield of 2 ATP for each glucose entering the reaction

Question 2

Anaerobic Respiration in Animals & Bacteria

Answer 2

1. Glycolysis occurs. Triose phosphate is converted to pyruvate with the release of ATP and reduction of NAD
2. Reduced NAD reduces the pyruvate, forming lactate
3. The oxidised NAD can again be reduced during glycolysis. The cycle continues

Question 3

Anaerobic Respiration in Plants and Fungi

Answer 3

1. Glycolysis occurs
2. Triose phosphate is converted to pyruvate with the release of ATP and reduction of NAD
3. Pyruvate is decarboxylated, releasing carbon dioxide and forming ethanal
4. Reduced NAD reduces the ethanal, forming ethanol
5. The oxidised NAD can again be reduced during glycolysis. The cycle continues