كويزات ونماذج الدفعة السابعة طب بشري /جامعة اب

1. About carbohydrates: a) derivatives of carbohydrates contain only carbon, hydrogen and oxygen b) monosaccharides are soluble in nonpolar solvents. c) monosaccharides can be hydrolyzed into simpler compounds d) the number of stereoisomers depend on the number of chiral carbon atoms✔️ 2. About carbohydrates: a) oligosaccharides consist of long chains of more than 10 monosaccharide units b) all polysaccharides are linear chains c) heteropolysaccharides contain only a single monosaccharide d) a heptose sugar contains 7 carbon atoms✔️ 3. Which of the following is an aldotetrose: a) glyceraldehyde b) erythrose✔️ c) mannose d) ribose 4. D-xylose is: a) a four carbon aldose b) has four chiral carbons c) involved in DNA synthesis d) a keto sugar e) a five carbon aldose✔️ 5. All the following are ketoses except: a) dihydroxyacetone b) ribose ✔️ ( aldoses) c) fructose d) xylulose e) ribulose 6. All of the following are hexose sugars except: a) Mannose b) Arabinose ✔️ ( pentoses ) c) Glucose d) Fructose e) Galactose 7. All of the following sugars are hexoses except: a) glucose b) fructose ✔️ ( ketoses ) c) mannose d) galactose e) ribose 8. Dextrose is: a) D-glucose ✔️ b) D-fructose c) dihydroxyacetone d) L-glucose e) L-sucrose 9. About carbohydrates: a) Dihydroxyacetone and glyceraldehyde have the same functional group ✖️ Because Dihydroxyacetone ⇒ keto group and glyceraldehyde ⇒ aldehyde group b) D-ribose and D-arabinose are epimers at carbon number 2 ✔️ c) D-ribose and D-arabinose are enantiomers d) optical isomers cannot rotate a plane of polarized light 10. How many isomers of sedoheptulose sugar? a) 2 b) 4 c) 12 d) 10 e) 16 ✔️ Because it has 4 asymmetric carbon atomes 4Alpa d sedoheptulose Alpa L  sedoheputlose 4beta d sedoheputlose        4beta L sedoheputlose 11. Galactose contains: a) one asymmetric carbon atom b) two asymmetric carbon atoms c) three asymmetric carbon atoms d) four asymmetric carbon atoms ✔️ 12. D-xylulose and D-ribulose are epimers with respect to: a) C1 b) C2 c) C3 ✔️ d) C4 e) C5 13. Mannose and galactose are epimers of glucose at carbon number: a) C2 and C4 respectively ✔️ ( Because glucose and mannose are an epimeric pair which differ only with respect to C2 and galactose is the 4th epimer ofglucose ) b) C2 and C5 respectively c) C3 and C5 respectively d) C1 and C4 respectively e) C3 and C4 respectively 14. Xylose and lyxose are epimers at carbon: a) C5 b) C2 ✔️ c) C3 d) C4 e) not epimers 15.The following is/are epimers of glucose: a) fructose b) mannose c) ribose d) galactose e) b & d ✔️ 16. The C2 epimer of glucose is: a) fructose b) galactose c) sedoheptulose d) mannose ✔️ 17. D-arabinose and D-ribose sugars are epimers with respect to: a) C1 b) C2 ✔️ c) C3 d) C5 e) C6 18. The D and L isomers of a ribose sugar takes place at: a) C1 b) C2 c) C3 d) C4 ✔️ e) C5 19. Alpha and beta configuration of D-fructofuranose depends on the position of: a) OH group on C1 with OH on C4 b) OH group on C1 with OH on C6 c) OH group on C2 with OH on C5 ✔️ Why ? (( Because 5-member furanose ring by reaction of the C2 keto group with the OH on C5 But if it is fructopyranose 6-member pyranose ring by reaction of the C2 keto group with the OH on C6 )) d) OH group on C2 with OH on C6 e) OH group on C1 with OH on C5 20. The compound on the right is: a) α-D-glucopyranose d) β-D- galactopyranose b) β-D- glucopyranose e) none of the above✔️ c) α-D-galactopyranose 21. Converting α-D-aldose to a β-D-aldose is called: a) reduction b) etherification c) mutarotation ✔️ d) epimerization 22. The anomeric carbon of fructose is at: a) C1 b) C2 ✔️ c) C3 d) C4 23. The monosaccharide with no isomerism and asymmetric carbon is: a) glucose b) fructose c) glyceraldehyde d) dihydroxyacetone ✔️ e) ribose 24. The following is a type of isomerism found only in the ring structure of monosaccharides and not in the open chain form: a) aldose-ketose isomerism b) epimerism c) anomerism ✔️ d) enantiomerism L & D isomerism كيمياء حيوية 1 #Biochemistry

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