HL Aerobic Cell Respiration

Where does the link reaction occur in aerobic cell respiration?

• Cytoplasm

• Mitochondrial matrix

• Nucleus

• Intermembrane space

Answer explanation

The link reaction occurs in the mitochondrial matrix during aerobic cell respiration.

What is produced when pyruvate is decarboxylated during the link reaction?

• Oxaloacetate and ATP

• Ethanol and CO2

• Lactate and NADH

• Acetyl-CoA and CO2

Answer explanation

During the link reaction, pyruvate is decarboxylated to produce Acetyl-CoA and CO2, which are essential for the next steps in cellular respiration.

Which molecule combines with acetyl-CoA to form citrate in the Krebs cycle?

• Succinate

• Fumarate

• Oxaloacetate

• Pyruvate

Answer explanation

Oxaloacetate combines with acetyl-CoA to form citrate in the Krebs cycle.

How many molecules of NADH are produced per acetyl-CoA molecule in the Krebs cycle?

• Two

• Three

• One

• Four

Answer explanation

In the Krebs cycle, each acetyl-CoA molecule produces 3 molecules of NADH. Therefore, three molecules of NADH are produced per acetyl-CoA molecule.

What is the role of NADH in the electron transport chain?

• To pump protons directly

• To donate electrons to the first carrier protein complex

• To act as the terminal electron acceptor

• To synthesize ATP

Answer explanation

NADH's role in the electron transport chain is to donate electrons to the first carrier protein complex.

What creates the proton gradient across the inner mitochondrial membrane?

• Flow of electrons along the electron transport chain

• Decarboxylation of pyruvate

• Oxidation of glucose

• Direct synthesis of ATP

Answer explanation

The proton gradient across the inner mitochondrial membrane is created by the flow of electrons along the electron transport chain.

What is chemiosmosis?

• The process of ATP synthesis driven by the flow of protons

• The decarboxylation of pyruvate

• The breakdown of glucose to pyruvate

• The formation of water from oxygen

Answer explanation

The process of ATP synthesis driven by the flow of protons

What is the role of oxygen in aerobic cell respiration?

• To act as the terminal electron acceptor

• To pump protons across the membrane

• To donate electrons to the electron transport chain

• To form acetyl-CoA

Answer explanation

Oxygen acts as the terminal electron acceptor in aerobic cell respiration, allowing the electron transport chain to function and produce ATP.

Which of the following statements is true about lipids as respiratory substrates?

• They provide a lower yield of energy per gram compared to carbohydrates

• They are more accessible for immediate energy needs

• They are broken down into fatty acids and glycerol

• They undergo glycolysis to form pyruvate

Answer explanation

The correct statement is that lipids are broken down into fatty acids and glycerol, making this the true statement about lipids as respiratory substrates.

What is the final product when oxygen combines with electrons and protons in the electron transport chain?

• ATP

• Water

• NADH

• Carbon dioxide

Answer explanation

When oxygen combines with electrons and protons in the electron transport chain, the final product is water.