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