Cellular Respiration Processes

00:00 16 marks

8. (a) Outline the process of glycolysis. [4]
(b) Explain the role of the electron transport chain and chemiosmosis in generating ATP during aerobic respiration. [7]
(c) Compare and contrast aerobic and anaerobic respiration in terms of substrates used, products formed, and ATP yield. [4]
*(Plus 1 mark for quality)*

Part a

6 minutes 4 marks

Question

Outline the process of glycolysis. [4]

Hint Hint

Hint

Focus on the key stages: phosphorylation, lysis, oxidation, and ATP/NADH production. Where does it happen?

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Glycolysis occurs in the cytoplasm. Glucose (6C) is phosphorylated (using 2 ATP) and lysed into two triose phosphates (3C). These are oxidized, reducing NAD+ to NADH and producing a net of 2 ATP via substrate-level phosphorylation, resulting in two pyruvate molecules.

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Part b

11 minutes 7 marks

Question

Explain the role of the electron transport chain and chemiosmosis in generating ATP during aerobic respiration. [7]

Hint Hint

Hint

Describe where this occurs, what powers the process (electron carriers), how the proton gradient is formed, and the role of ATP synthase and oxygen.

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In the inner mitochondrial membrane, NADH/FADH2 donate electrons to the ETC. Electron passage releases energy used to pump H+ from the matrix to the intermembrane space, creating a proton gradient. H+ flows back through ATP synthase (chemiosmosis), driving ATP synthesis. Oxygen is the final electron acceptor, forming water.

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Part c

6 minutes 4 marks

Question

Compare and contrast aerobic and anaerobic respiration in terms of substrates used, products formed, and ATP yield. [4]

Hint Hint

Hint

Consider key differences: oxygen requirement, location, final products (CO2/water vs. lactate/ethanol), and the relative amount of ATP produced per glucose.

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Comparison: Aerobic uses glucose/lipids/proteins, requires O2, occurs in cytoplasm & mitochondria, produces CO2/H2O, high ATP yield (~30-32). Anaerobic (human) uses glucose, no O2 needed, occurs in cytoplasm, produces lactate, low ATP yield (net 2).

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