Q: A food contains 4,000 μg of β-carotene. If 30% is absorbed and 100% of the absorbed β-carotene is converted to active vitamin A, how much active vitamin A is produced?

$$4,000 \times 0.3 = 1,200$$ μg absorbed; $$1,200 \times 1.0 = 1,200$$ μg active vitamin A

Q: If a spinach salad contains 4,000 μg of β-carotene and only 80% of β-carotene can still function as vitamin A after absorption, how much vitamin A is available?

$$4,000 \times 0.3 = 1,200$$ μg absorbed; $$1,200 \times 0.8 = 960$$ μg vitamin A

Question 1

Which of the following best explains why vitamins are considered essential micronutrients?

Accepted Answer

They are needed in small amounts and cannot always be synthesized by the body.

Question 2

How are vitamins classified based on their solubility?

Accepted Answer

Vitamins are classified as either water-soluble or fat-soluble.

Question 3

Which vitamin is an exception to the rule that vitamins cannot be synthesized by the body?

Accepted Answer

Vitamin D

Question 4

A patient is experiencing oxidative damage to cell membranes. Which vitamin would most likely help protect against this damage due to its antioxidant properties?

Accepted Answer

Vitamin E

Question 5

Which of the following statements about free radicals is correct?

Accepted Answer

Free radicals can damage cells by causing oxidative stress.

Question 6

What is the main function of antioxidants in the body?

Accepted Answer

Antioxidants destroy free radicals, preventing cell damage.

Question 7

Which of the following is TRUE regarding the naming of vitamins?

Accepted Answer

Vitamins are named in order of their discovery, with some letters skipped if substances were discarded.

Question 8

A food contains 4,000 μg of β-carotene. If 30% is absorbed and 100% of the absorbed β-carotene is converted to active vitamin A, how much active vitamin A is produced?

Accepted Answer

$$4,000 	imes 0.3 = 1,200$$ μg absorbed; $$1,200 	imes 1.0 = 1,200$$ μg active vitamin A

Question 9

Which statement best describes the difference between provitamin and preformed vitamin?

Accepted Answer

Provitamins must be converted into an active form in the body, while preformed vitamins are already active.

Question 10

If a spinach salad contains 4,000 μg of β-carotene and only 80% of β-carotene can still function as vitamin A after absorption, how much vitamin A is available?

Accepted Answer

$$4,000 	imes 0.3 = 1,200$$ μg absorbed; $$1,200 	imes 0.8 = 960$$ μg vitamin A

Question 11

Which of the following is NOT a function of vitamins?

Accepted Answer

Providing energy directly to cells

Question 12

Which statement about vitamin bioavailability is correct?

Accepted Answer

Bioavailability refers to the proportion of a nutrient that is absorbed and utilized by the body.

Question 13

Which of the following statements is TRUE regarding antioxidants?

Accepted Answer

Antioxidants protect cells by neutralizing free radicals.

Question 14

Which of the following vitamins is water-soluble?

Accepted Answer

Vitamin C

Question 15

A person consumes a diet high in preformed vitamin A. What is a potential risk associated with this?

Accepted Answer

Vitamin A toxicity due to excessive intake

Question 16

Which of the following is a correct statement about the role of phytochemicals?

Accepted Answer

Phytochemicals can function as antioxidants, helping prevent damage to cell membranes by free radicals.

Question 17

Which vitamin is most likely to be deficient in a person who avoids all animal products and does not take supplements?

Accepted Answer

Vitamin B12

Question 18

Which of the following statements is FALSE regarding vitamins?

Accepted Answer

Vitamins provide energy directly to the body.

Question 19

Which of the following is a multi-step process involving vitamin A from plant sources?

Accepted Answer

β-carotene is absorbed, converted to active vitamin A, and then utilized by the body.

Question 20

Which of the following best describes the chemical reaction that occurs when antioxidants neutralize free radicals?

Accepted Answer

Antioxidants donate electrons to free radicals, stabilizing them.

Introduction to Vitamins: Classification, Antioxidant Function, and Bioavailability

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