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VICBiologyQuick questions
Unit 3: How do cells maintain life?
Quick questions on Cellular respiration (glycolysis, Krebs cycle, electron transport chain): VCE Biology Unit 3
11short Q&A pairs drawn directly from our worked dot-point answer. For full context and worked exam questions, read the parent dot-point page.
What is link reaction (mitochondrial matrix)?Show answer
If oxygen is present, each pyruvate enters the mitochondrial matrix and is converted to acetyl-CoA (2 carbons), releasing one CO2 and producing one NADH. Two pyruvates per glucose therefore yield 2 acetyl-CoA, 2 CO2 and 2 NADH.
What is location?Show answer
The cytosol of every living cell.
What are inputs?Show answer
One glucose, 2 ATP (investment phase), 4 ADP + Pi, 2 NAD+.
What are outputs?Show answer
2 pyruvate (3 carbons each), 2 NADH, net 2 ATP (4 made, 2 invested).
What is process?Show answer
Glucose (6 carbons) is phosphorylated twice using 2 ATP, split into two 3-carbon intermediates, and oxidised. NAD+ accepts electrons and H+ to form NADH. ADP is phosphorylated to ATP by substrate-level phosphorylation.
What is per glucose?Show answer
4 CO2, 6 NADH, 2 FADH2, 2 ATP.
What are animal cells?Show answer
Pyruvate is reduced to lactate (lactic acid) by lactate dehydrogenase. NADH is reoxidised to NAD+. No CO2 is released.
What are plant and yeast cells?Show answer
Pyruvate is decarboxylated to acetaldehyde (releasing CO2), then reduced to ethanol by alcohol dehydrogenase. NADH is reoxidised to NAD+. This is the basis of brewing and bread-making.
What is q1?Show answer
State the location, net ATP yield and main output of glycolysis, the Krebs cycle and the electron transport chain. [4 marks]
What is q2?Show answer
One glucose yields about 36 ATP under aerobic conditions but only 2 ATP under anaerobic. (a) Calculate the efficiency loss percentage. (b) Explain why yeasts can still grow vigorously despite the lower ATP.
What is q3?Show answer
Refer to a Yarra Valley fermentation. (a) Write the word equation for ethanolic fermentation. (b) Predict what happens to the yeast at 14 percent alcohol.