12. Which of the following is measured in 24-hour urine in the diagnosis of adrenal medulla chromaffin cell tumors? A) Vitamin D B) Vanilmandelic acid C) Indoleacetic acid D) L-dopa E) 17-ketosteroid 13. Which of the following is not synthesized from cholesterol? A) Calcitriol B) Estrone C) Colic acid D) Adrenaline C) Aldosterone 14. Megaloblastic anemia, defined as pernicious anemia, occurs due to deficiency of which vitamin? A) Vitamin B12 B) Vitamin B2 C) Vitamin D D) Vitamin B1 E) Niacin 15. At physiologic pH,which component of nucleotides carries a negative charge? A) Ribose B) Adenine c)Deoxyribose D) Phosphate groups E) Urasil 16. What are the parts of chromosomes that determine or influence a single character or phenotype (visible trait), such as eye color? A) Chromatin B) Gene C) Codon D) Phosphate groups E) Histone 17. A complete, catalytically active enzyme with its cofactor is called __ Which of the following comes in the dotted place above? A) Apoprotein B)Coenzyme C) Holoenzyme D) Prostatic group E) Cofactor

12. B) Vanilmandelic acid<br />Vanilmandelic acid (VMA) is a metabolite of catecholamines, such as adrenaline and noradrenaline, which are produced by chromaffin cells in the adrenal medulla. In the diagnosis of adrenal medulla chromaffin cell tumors, VMA is measured in 24-hour urine as an indicator of catecholamine production.<br /><br />13. C) Colic acid<br />Colic acid is not synthesized from cholesterol. Cholesterol is a precursor for the synthesis of bile acids, steroid hormones, and other important molecules in the body. Calcitriol, estrone, adrenaline, and aldosterone are all synthesized from cholesterol.<br /><br />14. A) Vitamin B12<br />Megaloblastic anemia, also known as pernicious anemia, occurs due to a deficiency of vitamin B12. Vitamin B12 is essential for DNA synthesis and red blood cell production. A deficiency in vitamin B12 can lead to the production of large, abnormal red blood cells that are unable to function properly, resulting in anemia.<br /><br />15. D) Phosphate groups<br />At physiologic pH, the phosphate groups in nucleotides carry a negative charge. Nucleotides are the building blocks of DNA and RNA, and they consist of a sugar molecule (ribose or deoxyribose), a nitrogenous base (adenine, guanine, cytosine, thymine, or uracil), and one or more phosphate groups.<br /><br />16. B) Gene<br />Genes are the parts of chromosomes that determine or influence a single character or phenotype, such as eye color. Genes are segments of DNA that code for specific proteins or functions in the body. Each gene is located at a specific position on a chromosome and is responsible for the inheritance of a particular trait.<br /><br />17. C) Holoenzyme<br />A complete, catalytically active enzyme with its cofactor is called a holoenzyme. Enzymes are proteins that catalyze chemical reactions in the body. Some enzymes require additional non-protein components, called cofactors, to be fully active. When an enzyme is combined with its cofactor, it forms a holoenzyme that can catalyze the reaction.