question

1. Light first enters the eye through the cornea. 2. The retina is the light absorbing layer of the eye that contains the rod and cone cells. 3. A cell in the retina that is responsible for black and white vision, as well as night vision is a rod. 4. A cone is a cell in the retina responsible for color vision. 5. rhodopsin is a protein found in rods; it is needed for night vision. 6. A type of preformed vitamin A, retinal is found within the rhodopsin protein. 7. The name for the family of substances that are all types of preformed vitamin A is retinoids. 8. The process called bleaching occurs when light enters the eye and interacts with and changes rhodopsin, causing dissociation of vitamin A from rhodopsin.

answer

light contacts eye --> Light enters the eye through the cornea. --> Light travels to the macula within the retina--> Rhodopsin absorbs light, and the retinal changes shape. --> Retinal detaches from the rhodopsin, and some retinal is lost. --> Retinol is converted to retinal, which gets reincorporatedinto rhodopsin. --> Light-absorbing capabilities of proteins are regenerated

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sources of preformed vitamin A

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vitamin A fortified milk liver vitamin a supplements

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sources of provitamin a carotenoids

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cooked carrots basked sweet potatoes

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sources of both preformed vitamin a and provitamin a carotenoids as well as lutein

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kale turnip greens

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Some types of vitamin A are immediately usable by the body, while other types need to be converted first. Read the statements below and select the correct statements regarding the conversion of provitamin A carotenoids to retinol.

answer

-Retinol is the most usable form of preformed vitamin A. -Preformed vitamin A is only found in animal food sources, foods that are fortified, or supplements.

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Antioxidant minerals function as ______ within antioxidant enzyme systems.

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cofactors

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Oxidation is a chemical reaction that results in _____.

answer

loss of electrons

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Antioxidants work by ______ free radicals.

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stabilizing

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Antioxidant enzyme systems act by ______.

answer

converting free radicals to less damaging substances

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Which nutrient is a cofactor in antioxidant enzyme systems?

answer

Selenium

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Tocopherol compounds are biologically active forms of ________.

answer

vitamin E

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Vitamin C assists in ________.

answer

collagen synthesis

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Beta-carotene is a ________.

answer

carotenoid

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Consumption of excessive vitamin A during pregnancy can result in _____.

answer

birth defects

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Selenium is a trace mineral that appears to play a role in _____ function.

answer

immune

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Vitamin C deficiencies are rare in ______ countries.

answer

developed

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The primary function of vitamin E is to be a(n) _______.

answer

antioxidant

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Vitamin C is excreted easily because it is ______.

answer

water soluble

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Vitamin A is essential to _______.

answer

sight

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Selenium deficiency had been associated with _________.

answer

Keshan disease.

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Which of these foods is the best source of vitamin E?

answer

Canola oil

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Who is at greatest risk for vitamin E deficiency?

answer

People with liver or gallbladder diseases

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Vitamin C enhances _____ absorption.

answer

iron

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Which is the best food source of beta-carotene?

answer

pumpkin pie

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Which meal is likely to exceed the Upper Level (UL) for vitamin A?

answer

Liver and onions with a glass of wine

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The three major types of cancer treatment are radiation, chemotherapy, and ________.

answer

surgery

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One of the best things you can do to help prevent cancer is _________.

answer

not to smoke

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Infectious agents account for _____ of cancers worldwide.

answer

18%

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Cancer progresses in ______ stages.

answer

three

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Some of the signs and symptoms to watch for in cancer development include uncommon fatigue, unusual bleeding, and ________.

answer

unexplained weight loss

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An example of a modifiable risk factor identified by the American Cancer Society is ____.

answer

weight

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Most forms of cancer result in the formation of _________.

answer

tumors

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If cancer cells are proliferating and growing their own blood vessels, the cancer is likely in the _________ stage.

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progression

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An example of an action that decreases cancer risk is _________.

answer

eating a variety of brightly colored vegetables

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The cancer-treatment method that uses electron beams, rays, and photons to kill cancer cells is called ____.

answer

radiation

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nutrition chapter 8 mastering health – Flashcards

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