Q: Which of the following is the correct general reaction for transamination?

$$\text{Amino acid} + \text{\alpha-ketoglutarate} \rightarrow \text{\alpha-keto acid} + \text{glutamate}$$

Question 1

Which of the following best describes the role of the malate-aspartate shuttle in cellular metabolism?

Accepted Answer

It transfers electrons from NADH in the cytosol to NAD+ in the mitochondrial matrix, enabling oxidative phosphorylation.

Question 2

Which enzyme catalyzes the first committed step in fatty acid synthesis, and what is its regulatory molecule?

Accepted Answer

Acetyl-CoA carboxylase (ACC); regulated by malonyl-CoA

Question 3

A patient presents with elevated ketone bodies in the blood. Which of the following best explains the biochemical basis for this observation?

Accepted Answer

Excess acetyl-CoA from fatty acid oxidation is diverted to ketone body synthesis when the TCA cycle is limited.

Question 4

Which of the following statements about the electron transport chain (ETC) is correct?

Accepted Answer

Electrons from NADH enter the ETC at Complex I, while electrons from FADH2 enter at Complex II.

Question 5

Which equation correctly relates the standard free energy change ($$\Delta G^\circ) to $$the equilibrium constant ($$K$$)?

Accepted Answer

$$\Delta G^\circ = -RT \ln K$$

Question 6

During photosynthesis, which photosystem is responsible for the initial splitting of water and what is the ultimate electron acceptor in non-cyclic electron flow?

Accepted Answer

Photosystem II; NADP+

Question 7

Which of the following best describes substrate-level phosphorylation?

Accepted Answer

ATP synthesis directly coupled to a chemical reaction, such as the conversion of phosphoenolpyruvate to pyruvate.

Question 8

Which of the following amino acids is classified as both ketogenic and glucogenic?

Accepted Answer

Isoleucine

Question 9

A cell has a high ATP/ADP ratio. Which effect would this have on the TCA cycle?

Accepted Answer

It would inhibit the TCA cycle through allosteric regulation.

Question 10

Which of the following is the correct general reaction for transamination?

Accepted Answer

$$	ext{Amino acid} + 	ext{\alpha-ketoglutarate} ightarrow 	ext{\alpha-keto acid} + 	ext{glutamate}$$

Question 11

Which of the following best explains why the glyoxylate cycle is important in plants but not in animals?

Accepted Answer

It allows plants to convert fatty acids into glucose by bypassing the decarboxylation steps of the TCA cycle.

Question 12

Which of the following is a key regulatory effect of malonyl-CoA in lipid metabolism?

Accepted Answer

It inhibits the carnitine shuttle, preventing fatty acid entry into mitochondria.

Question 13

Which of the following equations correctly describes the free energy change ($$\Delta G) $$for a reaction under cellular conditions?

Accepted Answer

$$\Delta G = \Delta G^\circ + RT \ln Q$$

Question 14

Which of the following is NOT a product of ketone body synthesis from acetyl-CoA?

Accepted Answer

Malonate

Question 15

Which of the following best describes the function of Rubisco in the Calvin cycle?

Accepted Answer

It catalyzes the carboxylation of ribulose-1,5-bisphosphate with CO2.

Question 16

Which of the following statements about nitrogen fixation is correct?

Accepted Answer

It is performed by certain bacteria, such as Rhizobium, in symbiosis with plants.

Question 17

Which of the following best describes the glucose-alanine cycle?

Accepted Answer

It transfers nitrogen from muscle to liver in the form of alanine, which is converted to glucose.

Question 18

Which of the following is a key difference between fatty acid synthesis and degradation?

Accepted Answer

Synthesis uses NADPH as a reducing agent, while degradation produces NADH and FADH2.

Question 19

Which of the following best describes the role of the F0F1-ATPase (ATP synthase) in oxidative phosphorylation?

Accepted Answer

It uses the proton gradient to synthesize ATP from ADP and inorganic phosphate.

Comprehensive Study Notes: TCA Cycle, Electron Transport, Lipid Metabolism, Photosynthesis, and Nitrogen/Amino Acid Metabolism

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