9700 · 12.2
Respiration flashcards
Revision flashcards for Cambridge 9700 Respiration (syllabus 12.2). Flip, recall, then mark a real past-paper question.
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What is glycolysis and where does it occur?
A metabolic pathway that splits a 6-carbon glucose molecule into two 3-carbon pyruvate molecules. It occurs in the cytoplasm of the cell.
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What are the net products of glycolysis from one molecule of glucose?
2 Pyruvate, 2 ATP (net), and 2 reduced NAD (NADH).
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What is the purpose of the link reaction and where does it take place?
To convert pyruvate into acetyl CoA, linking glycolysis to the Krebs cycle. It occurs in the mitochondrial matrix.
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For each molecule of acetyl CoA that enters the Krebs cycle, what is produced?
1 ATP (by substrate-level phosphorylation), 3 reduced NAD, 1 reduced FAD, and 2 CO₂.
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What is the role of oxygen in aerobic respiration?
Oxygen is the final electron acceptor in the electron transport chain. It combines with electrons and protons (H⁺) to form water, allowing the ETC to continue functioning.
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Define chemiosmosis.
The movement of ions (specifically H⁺ protons) across a selectively permeable membrane, down their electrochemical gradient. This process is coupled to ATP synthesis by ATP synthase.
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What is the respiratory quotient (RQ)?
The ratio of the volume of carbon dioxide produced to the volume of oxygen consumed during respiration. The formula is $RQ = \frac{CO_2 \text{ produced}}{O_2 \text{ consumed}}$.
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What are the end products of anaerobic respiration in (a) animal muscle cells and (b) yeast?
(a) In animal muscle cells: Lactate. (b) In yeast: Ethanol and Carbon Dioxide.