851. In the co-enzyme B12the position occupied by a cyanide ion in vitamin B12 is bonded directly to the __________ of the ribose of adenosine.
A. adenine
B. 5-6 dimethylbenzimidazole
C. hydroxycobalamin
D. cyanocobalamin

852. The reductant, NADH, transfers the electrons via a flavo-proteins to the specific disulfide (S-S) protein to form a dithiol (SH,SH) protein which converts vitamin
A. B12(Co2+)to B12(Co)
B. B12(Co) to B12(Co2+)
C. B12(Co2+)to B12(Co+)
D. B12(Co+)to B12(Co2+)

853. An early sign of retinol deficiencies in man is
A. night blindness
B. keratinization
C. xeropthalmia
D. none of these

854. An enzyme, L-folate reductase reduces folic acid to
A. hydrofolic acid
B. dihydrofolic acid
C. trihydrofolic acid
D. tetrahydrofolic acid

855. What compound of raw egg white causes a syndrome similar to vitamin B deficiency?
A. Avidin
B. Betabindin
C. Ovalbumin
D. Albumin

856. The disease Beriberi is due to a dietary deficiency in
A. vitamin B1 (thiamine)
B. vitamin B2 (riboflavin)
C. vitamin B6 (pyridoxine)
D. vitamin B12

857. Which of these is a symptom of vitamin A deficiency?
A. Osteoporosis
B. Impaired taste perception
C. Blindness
D. Impaired blood clotting

858. Vitamin-C is considered as a
A. water soluble
B. fat soluble
C. fat and water soluble
D. none of these

859. The vitamin niacin is part of the __________ molecule.
A. ferredoxin
B. pyridoxal phosphate
C. pyrophosphate

860. Which of these hormones is a catecholamine?
A. Follitropin
B. Norepinephrine
C. Tetraiodothyronine
D. Tetrahydrofolate