-
Fat-soluble vitamins are not
C) absorbed directly into the bloodstream through the intestinal mucosal cells
-
Retinol is
C) the alcohol form of vitamin A
-
Vitamin A is present in animal foods and body storage as
D) retinyl esters
-
The form of vitamin A involved in the visual process is ___________
-retinal
-
The form of vitamin A that is involved in cellular differentiation is ____________
-retinoic acid
-
True/False (support your answer with an explanation)
Night vision is maintained by iodopsin, the light-sensitive pigment of the cones in the retina
False
Night vision is maintained by rhodopsin, the light-sensitive pigment of the rods in the retina
-
The greatest deman for vitamin A is for
D) epithelial tissue development and maintenance
-
True/False (support your answer with an explanation)
Vitamin A is involved in the reaborption of old bone during bone development
-True
-
Children in developing countries often become blind because
D) protein and zinc deficiencies interfere with the utilization and transport of vitamin A, and intake of all three nutrients is deficient
-
In developed countries, vitamin A deficiency is caused mainly by
B) malabsorption of fat
-
True/False (support your answer with an explanation)
Vitamin A supplements are effective in the treatment of acne
False
Only retinoic acid form of vitamin A has been proven effective for the treatment of acne. Vitamin A in supplements is normally in the form of retinol
-
Vitamin A toxicity may occur
D) when a vitamin A supplement that exceeds the RDA by five to ten times is used daily for several months
-
Of the symptoms listed below, only___________is not cause by vitamin A toxicity
D) inability to adapt to dim light
-
The richest sources of vitamin A are
B) liver and fish oils
-
Of the foods listed below, only____________is not a rich source of beta-carotene
C) beets
-
The precursor of vitamin D in the skin is called__________
-7-dehydrocholesterol
-
The most active of the following vitamin D metabolites is
D) 1,25-(OH)2 D3
-
The final active form of vitamin D is formed by
A) hydroxylation in the kidneys
-
Vitamin D does not stimulate
B) the synthesis of 7-dehydrocholesterol
-
Of the symptoms listed below,_____________would most likely be a result of vitamin D deficiency
B) enlarged joints in children
-
In children, the bone disease resulting from vitamin D deficiency is called__________; in adults, ____________
-
Of the groups listed below, only____________are not particularly susceptible to vitamin D deficiency
a) low income, dark-skinned children
b) infants who are exclusively breast-fed for long periods of time
c) pregnant women
d) elderly people who stay indoors
-pregnant women
-
Excessive vitamin D intakes by adults may result in
B) calcification of arteries
-
The Canadian Cancer Society recommends vitamin D intake be increased to 1000 IU
D) to reduce the risk of colorectal, breast, and prostate cancers
-
The most reliable source of vitamin D in Canada
A) fortified milk
-
Vitamin E functions in the body as
D) an antioxidant
-
A free radical is
a) a highly reactive molecule formed during the oxidation of saturated fatty acids
b) formed when vitamin E is oxidized
c) a highly reactive molecule formed during the oxidative of polyunsaturated fats
d) a compound containing paired electrons
-
c) a highly reactive molecule formed during the oxidative of polyunsaturated fats
-
A deficiency of vitamin E in humans is most likely to cause
D) hemolysis of red blood cells
-
The symptoms of vitamin E deficiency in animals and humans can be attributed mainly to
D) disupted cell membranes
-
Megadoses of vitamin E
D) rarely cause harm
-
Of the groups listed below, only____________would probably not benefit from a vitamin E supplement
A) people with muscular dystrophy
-
The need for vitamen E
D) increases with increasing polyunsaturated fat intake
-
Much of the vitamin E in the diet comes from
a) vegetable oils, margarine, and salad dressings
b) fruits and vegetables
c) milk products
d) liver
vegetable oils, margarine, and salad dressings
-
True/False (support your answer with an explanation)
After being used for deep-frying, oil can turn rancid with relative ease, because the vitamin E has lost its activity as an antioxidant
True
-
Vitamin K deficiency produces
A) hemorrhagic disease
-
Vitamin K deficiency is most likely to occur in
B) premature infants
-
Vitamin K is produced by micro-organisms in the
B) GI tract
-
True/False (support your answer with explanation)
Under normal circumstances, intestinal synthesis of vitamin K by micro-organisms can provide all of the amount the body needs
False
The intestinal biosynthesis of vitamin K by micro-organisms can supply only half of the body's requirement
-
The best dietary source of vitamin K is
B) green leafy vegetables
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