Nokea
During early tooth development, vitamin A deficiency leads to enamel hypoplasia and defective dentin formation. Because of its effect on soft tissues and bone, vitamin A contributes to normal spacing of teeth.
- A. Both statements are true.
- B. Both statements are false.
- C. The first statement is true; the second is false.
- D. The first statement is false; the second is true.
Correct Answer: A
Rationale: Both statements are true. The effect of vitamin A on the growth of soft tissues and bones naturally extends to the teeth and surrounding structures. Enamel hypoplasia, involving defective enamel matrix and incomplete calcification of enamel and dentin, can be due to vitamin A deficiency. The effect of this vitamin upon surrounding bone directly affects spacing patterns of the teeth within the bone and dentition. Choice A is correct because both statements accurately describe the influence of vitamin A on tooth development. Choices B, C, and D are incorrect as they do not reflect the accuracy of the statements provided.
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Which vitamin acts most like a hormone?
- A. Vitamin A
- B. Vitamin B
- C. Vitamin D
- D. Vitamin C
Correct Answer: C
Rationale: The correct answer is Vitamin D. Although vitamin D, also known as calciferol, has been called a vitamin, it is more appropriately classified as a hormone. Like hormones, vitamin D acts to control the function of other cell types. For example, it helps the body absorb and regulate skeletal calcium and phosphorus levels. Choice A (Vitamin A) plays a crucial role in vision and immune function. Choice B (Vitamin B) is a complex of different vitamins that play various roles in the body. Choice D (Vitamin C) is important for collagen production and acts as an antioxidant.
Each statement is true of vitamin K, except one. Which is the exception?
- A. Vitamin K is produced in the gut.
- B. Vitamin K functions as a catalyst for the synthesis of blood-clotting factors.
- C. Vitamin K maintains prothrombin levels.
- D. Vitamin K absorption increases with high levels of vitamin E supplementation.
Correct Answer: D
Rationale: The correct answer is D. Vitamin K absorption decreases with high levels of vitamin E supplementation because in larger amounts, vitamin E acts as an anticoagulant. Vitamin K is not produced in the gut but can be obtained from food sources or supplements. Vitamin K is essential for the synthesis of blood-clotting factors and is crucial in maintaining prothrombin levels, which is vital for proper blood clotting. The incorrect choice, D, is misleading as high levels of vitamin E supplementation hinder vitamin K absorption due to its anticoagulant properties. Dental hygienists should be aware of the importance of vitamin K in blood clotting, especially when treating patients who are on anticoagulant medications for conditions like stroke prevention.
Increasing the variety of foods often prevents nutrient excesses and toxicities. A dietary change to eliminate or increase intake of one specific food or nutrient usually alters the intake of other nutrients.
- A. Both statements are true.
- B. Both statements are false.
- C. The first statement is true; the second is false.
- D. The first statement is false; the second is true.
Correct Answer: D
Rationale: The first statement is false because increasing the variety of foods actually helps prevent nutrient excesses and toxicities. The second statement is true because making a dietary change to eliminate or increase the intake of a specific food or nutrient often leads to alterations in the intake of other nutrients. Choice A is incorrect because the first statement is false. Choice B is incorrect because the second statement is true. Choice C is incorrect because the first statement is false, even though the second statement is true.
Complex carbohydrates contain more than 10 monosaccharides. Complex carbohydrates are also called disaccharides.
- A. Both statements are true.
- B. Both statements are false.
- C. The first statement is true; the second is false.
- D. The first statement is false; the second is true.
Correct Answer: C
Rationale: The first statement is true; the second is false. Complex carbohydrates are also called polysaccharides and contain more than 10 monosaccharides. Choice A is incorrect because the second statement is false. Choice B is incorrect because the first statement is true. Choice D is incorrect because the second statement is false.
Each of the following is a fat-soluble vitamin except for one. Which is the exception?
- A. Vitamin A
- B. Vitamin C
- C. Vitamin D
- D. Vitamin K
Correct Answer: B
Rationale: The correct answer is B, Vitamin C. Vitamin C is a water-soluble vitamin, not fat-soluble. Fat-soluble vitamins are Vitamins A, D, E, and K. These vitamins are stored in the body's fat tissues and liver, unlike water-soluble vitamins which are not stored and are eliminated in urine, making them less likely to reach toxic levels.