1. Explain the similarities and differences in anaerobic and aerobic cellular respiration. (8 marks) SL aerobic requires oxygen and anaerobic does not utilize oxygen Answers MUST include both similarities and differences to receive full marks. Similarities (3 max) Differences (5 max)
Similarities (3 max) • both can start with glucose • both use glycolysis • both produce ATP/energy(heat) • both produce pyruvate • carbon dioxide is produced • (both start with glycolysis) aerobic leads to Krebs' cycle and anaerobic leads to fermentation
Differences (5 max) Anaerobic: • (fermentation) produces lactic acid in humans • (fermentation produces ethanol and CO2 in yeast • occurs in cytoplasm of the cell • recycles NADH (NAD+) Aerobic: • pyruvate transported to mitochondria • further oxidized to CO2 and water (in Krebs cycle) • produce a larger amount of ATP (36-38 ATP)/anaerobic produces less ATP (2) • can use other compounds / lipids / amino acids for energy
6. Outline the process of glycolysis. (5 marks) HL • glucose/hexose/6C sugar converted to form pyruvate • splitting of hexose (phosphate) / lysis • oxidation of triose phosphate • net gain of 2 NADH (+ H+) / reduced NAD • net gain of 2 ATP • substrate level phosphorylation • occurs in cytoplasm of cell • no O2 required • under feedback control / inhibition
7. Explain the reactions that occur in the matrix of the mitochondrion that are part of aerobic respiration. 8 marks HL • pyruvate is decarboxylated/ CO2 removed • link reaction/ pyruvate combined with CoA/ ethanoyl/acetyl CoA formed • pyruvate is oxidized/ hydrogen removed • reduction of NAD/ formation of NADH + H+ • whole conversion called oxidative decarboxylation • Krebs cycle • C2 + C4 ---> C6 • C6 ---> C5 giving off CO2 • C5 ---> C4 giving off CO2 • hydrogen atoms removed collected by hydrogen-carrying coenzymes • ATP formed by substrate level phosphorylation • oxygen accepts electrons/ oxygen combines with hydrogen • total yield per turn of Krebs cycle = 2 CO2,, 3 NADH + H+, 1 FADH2, 1 ATP (directly produced)