7. Which enzyme controls free guanine and hypoxanthine salvage?
(A) Adenosine phosphoribosyltransferase
(B) Hypoxanthine-guanine phosphoribosyltransferase
(C) Purine aminotransferase
(D) Purine amidotransferase
(E) Ribonucleotide reductase

3. A student introduces a specific mutation in a gene by using polymerase chain reaction (PCR) with a primer containing a single nucleotide change. This method is known as: (A) site-directed mutagenesis (B) southern blot hybridization (C) PCR reaction (D) DNA microarray analysis (E) CRISPR interference

4. Which of the following is a second messenger in signal transduction pathways? (A) Insulin (B) ATP (C) G protein β subunit (D) CAMP (E) Tyrosine kinase

5. The hyperchromic effect observed when DNA is denatured refers to: (A) The decrease in absorbance at 260 nm upon separation of strands. (B) The increase in absorbance at 260 nm when strands separate. (C) The increase in absorbance at 260 nm when strands are degraded. (D) The shift in absorbance peak to 280 nm after hydrolysis. (E) The shift in absorbance peak to 260 nm after hydrolysis.

6. What deficiency would lead to the symptom of pernicious anemia? (A) Vitamin B12 (B) Vitamin C (C) Biotin (D) Vitamin E (E) Calcium cation

8. How much free ammonia would one AMP catabolism lead to? (A) 2 (B) 3 (C) 4 (D) 5 (E) 6

9. What type of secondary structure shown below is? (A) Type I α turn (B) Type II α turn (C) Type I β turn (D) Type II β turn (E) Type III β turn

10. According to the Bohr effect, given the following graph, how much more O2 can be delivered by hemoglobin to the peripheral tissue when the peripheral tissue elevates the concentration of CO2?  (A) 20% (B) 30% (C) 35% (D) 40% (E) 45%

11. Which amino acid catabolism can lead to the formation of α-ketoadipate? (A) Methionine, Histidine (B) Glycine, Cysteine (C) Leucine, Serine (D) Lysine, Tryptophan (E) Valine, Phenylalanine

12. Which of the following statements about fatty acids is correct? (A) Fatty acids are primarily stored in the body as triglycerides in muscle tissue. (B) Fatty acids with a higher number of double bonds tend to be more hydrophobic. (C) Omega-3 fatty acids are known to be beneficial for cardiovascular health. (D) Fatty acids are not involved in energy metabolism under normal conditions. (E) Short-chain fatty acids are typically found in significant amounts in dietary fats.

13. Cholesterol is synthesized from: (A) acetyl-CoA (B) malate (C) oxalate (D) lipoic acid (E) choline