2. Which of the following is NOT a product of photosynthesis?
(A) Glucose.
(B) Oxygen.
(C) ATP.
(D) NADPH.
(E) Water.

48. 2,4-Dinitrophenol and oligomycin inhibit mitochondrial oxidative phosphorylation. 2,4-Dinitrophenol is an uncoupling agent; oligomycin blocks the ATP synthesis reaction itself. Therefore, 2,4-dinitrophenol will: (A) allow electron transfer in the presence of oligomycin. (B) allow oxidative phosphorylation in the presence of oligomycin. (C) block electron transfer in the presence of oligomycin. (D) diminish O2 consumption in the presence of oligomycin. (E) None of the above.

49. All are physiological changes initiated by glucagon   except  : (A) activation of glycogenolysis in liver. (B) stimulation of liver gluconeogenesis. (C) long-term maintenance of steady-state levels of glucose in the blood stream. (D) activation of glycogenolysis in muscles. (E) All are true.

50. A molecule such as 2,4-dinitrophenol (2,4-DNP) works to uncouple the proton gradient. Which of the following is true about 2,4-DNP? (A) 2,4-DNP is protonated in the matrix and deprotonated in the intermembrane space. (B) The presence of an uncoupler results in an increase in the activity of the TCA cycle and electron transport. (C) 2,4-DNP is a very ineffective uncoupler because its hydrophobic structure prevents it from effectively crossing lipid bilayer membranes. (D) 2,4-DNP has been used as a very effective diet aid for the past 70 years. (E) None of the above is correct.

1. Which of the following statements about the comparison between RNA and DNA synthesis processes is correct? (A) During RNA synthesis, RNA polymerase requires the removal of nucleosomes to initiate transcription, whereas DNA replication does not involve nucleosome remodeling. (B) RNA polymerase does not require proofreading during RNA synthesis, whereas DNA polymerase has 3'-5' exonuclease proofreading activity. (C) Both RNA and DNA synthesis require the binding of DnaA protein to recognize the initiation site. (D) RNA synthesis uses only dNTPs (deoxynucleotide triphosphates) as substrates, whereas DNA synthesis utilizes both NTPs (nucleotide triphosphates) and dNTPs as substrates. (E) Both RNA and DNA synthesis use DNA as a template, and neither process requires any protein-assisted initiation complex formation.

3. In patients with certain genetic diseases, a defect in the carnitine transporter can lead to which of the following conditions? (A) Fatty acids cannot enter the mitochondria for oxidation. (B) Glucose cannot enter the mitochondria for oxidation. (C) Proteins cannot enter the mitochondria. (D) ATP synthesis increases. (E) Elevation of intracellular ketone body levels.

4. Which of the following statements regarding the functions of RNA and DNA is INCORRECT? (A) DNA is primarily responsible for storing genetic information. (B) mRNA carries genetic information and is used for protein synthesis. (C) tRNA is involved in the process of protein translation. (D) rRNA is a major component of ribosomes and participates in protein synthesis. (E) miRNA can regulate gene expression but cannot degrade mRNA.

5. Under anaerobic conditions, ATP generation primarily relies on which of the following pathways? (A) Electron transport chain (B) Oxidative phosphorylation (C) Glycolysis (D) Citric acid cycle (E) β-oxidation

6. Which of the following enzymes is directly responsible for the elongation of fatty acid chains during de novo fatty acid synthesis? (A) Acetyl-CoA carboxylase. (B) Acyl-CoA dehydrogenase. (C) Fatty acid synthase. (D) B-ketoacyl-ACP synthase. (E) Carnitine acyltransferase.

7. Which enzyme catalyzes the rate-limiting step in the citric acid cycle and is inhibited by ATP? (A) Citrate synthase. (B) a-ketoglutarate dehydrogenase complex. (C) Isocitrate dehydrogenase. (D) Malate dehydrogenase. (E) Succinate dehydrogenase.

8. Regarding eukaryotic translation and the structure and function of tRNA, which of the following statements is correct? (A) During translation, the small ribosomal subunit is responsible for peptide bond formation, while the large subunit scans and pairs the ribosome with the start codon of the mRNA. (B) During the recognition and attachment of the correct amino acid to tRNA, aminoacyl-tRNA synthetase verifies the side-chain structure of the amino acid and the anticodon of the tRNA to ensure specificity. (C) The E-site of the ribosome is the entry site for aminoacyl-tRNA, while the P-site is the location where decoding occurs. (D) Eukaryotic translation initiation requires eIF2 (eukaryotic initiation factor 2) to assist in loading the initiator tRNA into the large ribosomal subunit and directly position the start codon on the mRNA via the 5' cap structure. (E) The TYC arm of tRNA interacts with the ribosome to help tRNA enter the ribosome, while the DHU arm is responsible for the specific recognition by aminoacyl-tRNA synthetase.