IB Respiration HL: Kreb's cycle and the Electron Transport Chain

How many times is a molecule decarboxylated in the Krebs cycle per glucose molecule?

• 1

• 2

• 3

• 4

Answer explanation

6C citric acid --> 5C molecule and 5C --> 4C has a carbon removed when producing CO₂ so decarboxylation occurs twice. 2 acetyl CoA are produced from each glucose and so you need to multiply by 2 to take this into account.

Where, precisely, in the cell does the Krebs cycle occur?

(a)  

Which molecule is oxidised to produce FADH₂?

• 2C compound (acetyl coenzyme A)

• 4C compound (oxaloacetic acid)

• 5C compound (alpha-keto glutaric acid)

• FAD

How much ATP is produced in the Krebs cycle from each acetyl CoA that is inputted?

• 0

• 1

• 2

• 3

Answer explanation

Since it's per acteyl CoA and not per glucose you only need to take into account a single cycle.

Tags

NGSS.HS-LS1-7

Coenzyme A is recycled to be used in which process?

(a)  

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NGSS.HS-LS1-7

Which molecules are oxidised to produce NADH (reduced NAD)?

• 6C-citric acid

• 5C molecule

• 4C molecule

• Oxaloacetic acid

Answer explanation

When each molecule is oxidised they lose hydrogen atoms which are donated to NAD⁺

Tags

NGSS.HS-LS2-5

Select the products of the Krebs cycle

• NADH

• FADH₂

• ATP

• CO₂

In the electron transport chain, Oxygen acts as...

• a carrier of electrons, passing electrons down the chain

• a reducing agent

• the final electron acceptor

• a coenzyme

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NGSS.HS-LS1-7

When protons are pumped outside the matrix, across the inner membrane...

• water is made

• a concentration gradient of H⁺ ions (protons) is created

• NADH gets reduced

• CO₂ is produced

Tags

NGSS.HS-LS1-7

NGSS.HS-LS2-3

The electrons that are transferred through the electron transport chain initially belonged to

• NADH

• FADH₂

• ATP

• Oxygen

• NADH and FADH₂

Tags

NGSS.HS-LS1-7