Question 1

Which of the following best describes the relationship between the reduction potential ($$E^\circ') $$and the standard free energy change ($$\Delta G^\circ') $$for a redox reaction?

Accepted Answer

$$\Delta G^\circ' = -nF E^\circ'$$

Question 2

Which of the following cofactors is capable of both one-electron and two-electron transfer, and can exist in fully oxidized, semiquinone (radical), and fully reduced states?

Accepted Answer

Ubiquinone (Coenzyme Q)

Question 3

In the mitochondrial electron transport chain, which complex is responsible for both electron transfer and proton pumping?

Accepted Answer

Complex I (NADH:ubiquinone oxidoreductase)

Question 4

A patient is exposed to cyanide, which inhibits cytochrome c oxidase (Complex IV). What would you expect to happen to oxygen consumption and ATP production in their mitochondria?

Accepted Answer

Both oxygen consumption and ATP production decrease

Question 5

Which of the following best explains how the chemiosmotic theory accounts for ATP synthesis in mitochondria?

Accepted Answer

A proton gradient across the inner mitochondrial membrane drives ATP synthesis via ATP synthase

Question 6

Which subunit of ATP synthase rotates in response to proton flow, driving conformational changes in the catalytic sites?

Accepted Answer

c-subunit

Question 7

The energetics of ATP synthesis by ATP synthase depend on which two components of the proton motive force?

Accepted Answer

The chemical gradient ($$\Delta pH) $$and the electrical potential ($$\Delta \Psi)$$

Question 8

During photophosphorylation in chloroplasts, what is the primary source of electrons that are excited by light energy?

Accepted Answer

Water ($$H_2O)$$

Question 9

Which of the following best describes the role of the oxygen-evolving complex in photosystem II?

Accepted Answer

It splits water to provide electrons for the photosystem

Question 10

Which of the following statements about the regulation of enzyme activity is correct?

Accepted Answer

Enzyme activity can be regulated by allosteric effectors, covalent modification, and changes in gene expression

Question 11

If an enzyme has a $$K_m of 5 mM $$for its substrate, what substrate concentration is required to achieve approximately 90% of its maximal velocity ($$V_{max}$$)?

Accepted Answer

About 45 mM

Question 12

Which of the following best describes the role of AMP-activated protein kinase (AMPK) in metabolic regulation?

Accepted Answer

AMPK activates catabolic pathways and inhibits anabolic pathways in response to low energy

Question 13

During beta-oxidation of fatty acids, what is the main reason for activating the beta-carbon (B carbon) to a thioester (anhydride) intermediate?

Accepted Answer

The thioester is labile and stabilizes the carbanion formed during cleavage

Question 14

How many rounds of beta-oxidation are required to completely oxidize palmitic acid (C$$_{16}$$:0) to acetyl-CoA?

Accepted Answer

7

Question 15

Which of the following is a correct pathway for lipids to reach the bloodstream after a meal?

Accepted Answer

Dietary fats are packaged into chylomicrons in the intestine, transported via lymph, and released into the blood

Question 16

Which of the following statements about the fate of electrons from NADH and FADH$$_2 in $$the mitochondrial respiratory chain is correct?

Accepted Answer

Electrons from NADH enter at Complex I, while electrons from FADH$$_2$$ enter at Complex II

Question 17

Which of the following best describes the effect of an uncoupler (such as DNP) on oxidative phosphorylation?

Accepted Answer

It dissipates the proton gradient, decreasing ATP synthesis but increasing oxygen consumption

Question 18

Which of the following is a key difference between one-electron and two-electron carriers in the electron transport chain?

Accepted Answer

Iron-sulfur clusters transfer one electron at a time, while NADH transfers two electrons at a time

Question 19

In photosynthesis, what is the main function of the light-harvesting complex II (LHCII)?

Accepted Answer

To absorb photons and transfer excitation energy to the reaction center

Exam 2 Review: Oxidative Phosphorylation, ATP Synthase, Photophosphorylation, Metabolic Control, and Fatty Acid Oxidation

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