What are vitamins classified as in terms of their role in nutrition?
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(A)
Essential nutrients
2
Which of the following best describes Vitamin A (retinal) from a chemical perspective?
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(B)
A compound containing a cyclohexenyl ring
3
What enzyme is responsible for breaking down β-Carotene, a Vitamin A precursor?
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(A)
An enzyme involved in dioxygenation
4
In the intestinal lining, what cofactor is required by retinaldehyde reductase to convert retinal to retinol?
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(A)
A form of NADPH
5
Which of the following foods is a significant source of preformed Vitamin A?
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(A)
Dairy products, fats, and organ meats
6
The conversion between retinol and retinal necessitates the presence of a dehydrogenase or reductase, which, in turn, requires which of the following cofactors?
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(A)
NAD or NADP
7
What is a characteristic of fat-soluble vitamins?
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(D)
All of the above
8
What is the standard used to define one international unit of Vitamin A?
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(A)
The activity of 0.3 µg of Vitamin A alcohol
9
At what temperature does Lumirhodopsin remain stable?
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(D)
Below -50°C
10
In the bloodstream, how is retinol transported?
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(A)
Bound to a specific binding protein
11
What is the typical blood serum level of vitamin A, measured in mg per 100 ml?
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(B)
15-60
12
Which of the following is a symptom associated with a lack of vitamin A?
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(B)
Night blindness
13
A deficiency in Vitamin A can lead to which condition?
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(A)
Xeropthalmia
14
What is a key role that vitamin A plays in the body?
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(D)
To maintain the integrity of epithelial tissue
15
Which visual pigment contains retinal as a key component?
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(B)
Rhodopsin
16
In what process does retinoic acid take part?
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(C)
Glycoprotein
17
What form of retinal results when rhodopsin is exposed to light?
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(A)
All trans-retinal
18
The Carr-Price reaction is utilized for identifying which vitamin?
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(A)
Vitamin A
19
The following structure represents which of the following substances?
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(A)
Cholecalciferol
20
Under what condition is the absorption of Vitamin D enhanced?
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(A)
Acid pH of intestine
21
Which of the following is the most active form of Vitamin D in the body?
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(B)
1,25-Dihydroxycholecalciferol
22
What is the typical range for 25-hydroxycholecalciferol levels in a blood test, measured in ng/ml?
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(D)
8-55
23
What is the normal range for 1,25-dihydroxycholecalciferol in the blood, expressed in pg/ml?
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(A)
26-65
24
What is the typical concentration of 24,25-dihydroxycholecalciferol in the blood, measured in ng/ml?
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(C)
1-5
25
Which of the following is NOT a good source of Vitamin D?
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(C)
Milk
26
Which of the listed options contains the highest concentration of Vitamin D?
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(A)
Fish liver oils
27
A lack of Vitamin D can lead to which of these conditions?
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(A)
Rickets and osteomalacia
28
The biological activity of one international unit (I.U) of vitamin D is equivalent to how much cholecalciferol?
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(A)
0.025 µg of cholecalciferol
29
What type of light causes the breakdown of the ẞ-ring of 7-dehydrocholesterol, leading to the production of cholecalciferol?
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(C)
Ultraviolet irridation with sunlight
30
Which organs are involved in the synthesis of calcitriol?
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(A)
Both liver and kidney
31
Which substance contains a negligible amount of Vitamin E?
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(D)
Fish liver oil
32
What factor negatively impacts the effectiveness of tocopherols?
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(A)
Commercial cooking
33
Increased intake of which dietary component elevates the need for vitamin E?
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(C)
Polyunsaturated fat
34
Which mineral's demand is lowered by vitamin E?
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(C)
Selenium
35
Which of the following is considered a key natural antioxidant?
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(B)
Vitamin E
36
What process do tocopherols inhibit?
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(A)
Vitamin A oxidation
37
Creatinuria is linked to a shortage of which vitamin?
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(C)
E
38
Which scenario does NOT lead to a true or apparent lack of vitamin K?
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(B)
Total lack of red meat in the diet
39
Where is vitamin K primarily sourced from?
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(A)
Green leafy plants
40
What is a primary function of Vitamin A?
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(D)
All of these
41
From which source was Vitamin K initially extracted?
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(D)
Putrid fish meal
42
Which vitamin is produced by bacteria in the intestines?
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(D)
K
43
Vitamin K aids in modifying blood clotting factors by serving as a helper molecule for which enzyme?
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(A)
Carboxylase
44
Vitamin K assists in which process?
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(A)
Gamma carboxylation of glutamic acid residue
45
An excess of Vitamin K in newborns might lead to which condition?
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(B)
Jaundice
46
Dicoumarol counteracts the effects of which vitamin?
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(C)
Menadione
47
For those consuming large amounts of vitamin C, what is the typical serum ascorbic acid level?
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(A)
1-1.4 µg/100 ml
48
Which vitamin is most likely to be lacking in someone following a diet exclusively consisting of meat?
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(C)
Vitamin C
49
Where is the highest concentration of ascorbic acid found in the human body?
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(B)
Adrenal cortex
50
Which vitamin is essential for creating hydroxyproline (in collagen)?
