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