Nokea
Cariogenic foods and beverages, which are fermentable carbohydrates that can be metabolized by oral bacteria, reduce salivary pH to what critical level?
- A. 5
- B. 5.5
- C. 6
- D. 6.5
Correct Answer: B
Rationale: Cariogenic foods and beverages lower the pH level in the mouth to below 5.5. This is a critical threshold, as it is the point at which enamel begins to demineralize, increasing the risk of dental caries. Therefore, options 'A', 'C', and 'D' are incorrect. Although a pH level of 5, as suggested by option 'A', would indeed lead to demineralization, it's not the threshold value. The pH levels suggested by options 'C' and 'D' (6 and 6.5, respectively) are higher than the critical value of 5.5, which means they would not initiate enamel demineralization and the subsequent risk of dental caries.
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An essential nutrient must:
- A. be eaten every day
- B. be obtained by the diet
- C. be water soluble
- D. be eaten at every meal
Correct Answer: B
Rationale: The correct answer is B: 'be obtained by the diet.' Essential nutrients are those that the body cannot synthesize in sufficient quantities and must therefore be obtained through the diet. Choice A is incorrect because not all essential nutrients need to be consumed daily; the frequency of consumption varies. Choice C is incorrect because not all essential nutrients are water-soluble; they can be water-soluble or fat-soluble. Choice D is incorrect because essential nutrients do not need to be consumed at every meal, but rather need to be included in the overall diet regularly.
Does the reduction in oxidative damage that occurs with energy restriction in animals also occur in people whose diets include _____?
- A. fiber and carbohydrates
- B. fatty acids and protein
- C. probiotics
- D. antioxidants and phytochemicals
Correct Answer: D
Rationale: The correct answer is 'antioxidants and phytochemicals'. Antioxidants and phytochemicals help reduce oxidative damage in the body, contributing to healthy aging and a lower risk of chronic diseases. This is the same effect observed in animals when their energy intake is restricted. The other choices are incorrect as there is no direct evidence connecting reduced oxidative damage with diets high in fiber and carbohydrates, fatty acids and protein, or probiotics.
Which condition is most closely associated with a high rate of gastroesophageal reflux disease?
- A. Pregnancy
- B. Anorexia
- C. Hypertension
- D. Diabetes mellitus
Correct Answer: A
Rationale: Pregnancy is the correct answer as it is most closely associated with a high rate of gastroesophageal reflux disease (GERD). During pregnancy, the growing fetus exerts pressure on the stomach, leading to the backflow of stomach acid into the esophagus, causing GERD. This physiological change is a common occurrence in pregnant individuals. Conversely, anorexia, hypertension, and diabetes mellitus are not typically linked to a high rate of GERD. While these conditions have their own effects on the body, they do not directly contribute to the mechanisms that cause GERD, unlike the physical changes associated with pregnancy. Therefore, choices B, C, and D are incorrect.
Which mineral is a principal component of cell membranes?
- A. phosphorus
- B. magnesium
- C. iron
- D. iodine
Correct Answer: A
Rationale: Phosphorus is the correct answer. It is a key component of cell membranes, being part of the phospholipid bilayer that provides structure and controls the movement of substances in and out of cells. Magnesium, iron, and iodine do not serve as principal components of cell membranes. Magnesium is involved in various enzymatic reactions, iron is essential for oxygen transport, and iodine plays a role in thyroid hormone synthesis.
Which of the following statements is false?
- A. People with a vitamin K deficiency experience increased clotting time
- B. The major function of vitamin E is promoting vision
- C. Vitamin D functions as a hormone
- D. Rich sources of beta-carotene include carrots, sweet potatoes, and butternut squash
Correct Answer: B
Rationale: The statement that the major function of vitamin E is promoting vision is incorrect. Vitamin E primarily acts as an antioxidant, protecting cells from oxidative damage. Its role is not primarily related to vision, which is a major function of vitamin A. On the other hand, the other options are true. Vitamin K deficiency does indeed lead to increased clotting time, vitamin D functions as a hormone, and carrots, sweet potatoes, and butternut squash are rich sources of beta-carotene.