11.Which of the following describes an association of vitamin A and vision?

a.Retinoic acid is the form required for synthesis of retinoblasts.

b.Light causes retinal to shift from a cis to a trans configuration.

c.Retinol is the form bound to beta-carotene in the corneal membrane.

d.Pigment molecules in the retina are composed of a molecule of vitamin A bound to an omega-3 fatty acid.

12.Which of the following is the name of the vitamin A compound that is active in the visual response?

a.opsin

b.keratin

c.retinal

d.carotene

13.Which of the following describes an event in the visual response process?

a.Light energy strikes the retina and excites pigments to release retinal.

b.Light energy strikes the cornea and excites pigments to release retinoic acid.

c.Visual pigments deep in the brain are excited by light transmitted through the retina.

d.Epithelial cells on the surface of the eye respond to light energy by transmitting opsin molecules along nerve pathways to the brain.

14.Approximately what percent of the body’s vitamin A stores are found in the liver?

a.20 percent

b.50 percent

c.70 percent

d.90 percent

15.What tissue contains the majority of the body’s store of vitamin A?

a.liver

b.adipose

c.retinal cells

d.intestinal mucosal cells

16.Which of the following describes the primary function of vitamin A in bone health?

a.It stimulates uptake of calcium from the intestines.

b.It promotes synthesis of specific bone proteins involved in the mineralization process.

c.It assists enzymes that degrade certain regions of the bone thereby allowing remodelling to occur.

d.It inhibits oxidation of bone mucopolysaccharides thereby preserving bone crystal integrity and promoting growth.

17.If a normal, healthy adult were to begin consuming a vitamin A-poor diet, approximately how much time would pass before the first deficiency symptoms would appear?

a.2 weeks

b.1–2 months

c.6 months

d.1–2 years

18.Greg says that he usually eats 1 medium carrot every day to ensure that he’s consuming enough vitamin A. Today he said he didn’t eat any carrots and is worried that there is not enough vitamin A in his system. Which of the following would you say to Greg to allay his fear?

a.“Take a vitamin A supplement as soon as you can!”

b.“As long as you eat some chicken tonight you will not develop any deficiency.”

c.“Well, there isn’t any vitamin A in carrots so you probably haven’t consumed vitamin A for some time now.”

d.“Don’t worry; fat-soluble vitamins are stored in the body. It takes a lot longer than one day to develop any adverse effects.”

19.Approximately how many children worldwide have vitamin A deficiency?

a.5 million

b.25 million

c.250 million

d.500 million

20.Why does vitamin A status depend on the person’s protein status?

a.Adequate protein intake is a marker for liberal intake of vitamin A.

b.Dietary protein assures synthesis of vitamin A’s GI tract transporter.

c.Adequate protein intake reduces the risk for infection from bacteria that degrade vitamin A.

d.Transport of vitamin A within the body requires sufficient protein to synthesize retinol-binding protein.