Multiple Choice
Where in the cell do the Krebs cycle and electron transport chain occur?
27
views
8. Respiration
Krebs Cycle
Struggling with General Biology?
Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Which of the following statements is TRUE regarding one round of the Krebs cycle?
A
Four molecules of ATP are produced directly.
B
NADH is not produced during the cycle.
C
Two molecules of CO$_2$ are released.
D
The cycle begins with the combination of oxaloacetate and pyruvate.
Verified step by step guidance1
Step 1: Understand the Krebs cycle (also known as the citric acid cycle or TCA cycle). It is a series of chemical reactions that occur in the mitochondrial matrix, where acetyl-CoA is oxidized to produce energy intermediates such as NADH, FADH$_2$, and ATP (or GTP).
Step 2: Analyze the first statement: 'Four molecules of ATP are produced directly.' This is incorrect because only one molecule of ATP (or GTP, depending on the cell type) is produced per cycle. ATP is generated through substrate-level phosphorylation.
Step 3: Analyze the second statement: 'NADH is not produced during the cycle.' This is incorrect because three molecules of NADH are produced per cycle as a result of the oxidation of intermediates (e.g., isocitrate, α-ketoglutarate, and malate).
Step 4: Analyze the third statement: 'Two molecules of CO$_2$ are released.' This is correct because during one round of the Krebs cycle, two molecules of CO$_2$ are released as byproducts of the decarboxylation reactions involving isocitrate and α-ketoglutarate.
Step 5: Analyze the fourth statement: 'The cycle begins with the combination of oxaloacetate and pyruvate.' This is incorrect because the cycle begins with the combination of oxaloacetate and acetyl-CoA (not pyruvate) to form citrate.
Related Videos
Related Practice
