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Cellular Respiration Flashcards
Free A Level Biology Revision Cards
These free Biology flashcards cover the full pathway of cellular respiration, from glycolysis and the link reaction through to the electron transport chain and ATP synthesis.
Question
What is cellular respiration?
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Answer
The process by which cells break down glucose to release energy in the form of ATP. It occurs in all living cells and can be aerobic (with oxygen) or anaerobic (without oxygen).
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Question
Write the word equation for aerobic respiration.
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Answer
Glucose + oxygen → carbon dioxide + water (+ energy released as ATP)
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Question
Write the balanced symbol equation for aerobic respiration.
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Answer
C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O
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Question
What is ATP?
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Answer
Adenosine triphosphate — the universal energy currency of cells. Energy is released when ATP is hydrolysed to ADP + Pᵢ, and stored when ADP is phosphorylated back to ATP.
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Question
Where does aerobic respiration occur in the cell?
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Answer
Glycolysis occurs in the cytoplasm. The Krebs cycle occurs in the mitochondrial matrix. Oxidative phosphorylation (electron transport chain) occurs on the inner mitochondrial membrane.
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Question
What is glycolysis?
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Answer
The first stage of respiration — glucose (6C) is split into two pyruvate molecules (3C) in the cytoplasm, producing a net gain of 2 ATP and 2 NADH.
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Question
What happens to pyruvate in aerobic conditions?
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Answer
Pyruvate enters the mitochondria, is converted to acetyl-CoA (releasing CO₂), and enters the Krebs cycle.
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Question
What does the Krebs cycle produce?
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Answer
For each turn: 2 CO₂, 3 NADH, 1 FADH₂, and 1 ATP. It runs twice per glucose molecule (once per pyruvate).
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Question
What is the electron transport chain?
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Answer
A series of protein complexes on the inner mitochondrial membrane. Electrons from NADH and FADH₂ are passed along the chain, driving proton pumps that generate ATP via chemiosmosis.
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Question
What is the overall ATP yield from one glucose in aerobic respiration?
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Answer
Approximately 30–32 ATP per glucose molecule under cellular conditions.
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