Which lipoprotein increases the risk of cardiovascular disease?
- A. Low-density lipoprotein (LDL)
- B. High-density lipoprotein (HDL)
- C. Very low-density lipoprotein (VLDL)
- D. Chylomicrons
Correct Answer: A
Rationale: The correct answer is A: Low-density lipoprotein (LDL). LDL is often referred to as 'bad cholesterol' because it can lead to plaque buildup in arteries, increasing the risk of cardiovascular disease. High-density lipoprotein (HDL) is considered 'good cholesterol' as it helps remove LDL from the arteries, reducing the risk of cardiovascular issues. Very low-density lipoprotein (VLDL) and chylomicrons are also lipoproteins that transport fats in the bloodstream, but they are not as strongly associated with an increased risk of cardiovascular disease as LDL.
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Which hormone is responsible for stimulating the gallbladder to contract and release bile?
- A. gastric lipase
- B. cholecystokinin
- C. vitamin D
- D. enterokinin
Correct Answer: B
Rationale: Cholecystokinin (CCK) is the correct answer. It is the hormone responsible for stimulating the gallbladder to contract and release bile to aid in fat digestion. Gastric lipase (Choice A) is an enzyme that breaks down fats in the stomach, not a hormone involved in gallbladder function. Vitamin D (Choice C) is important for calcium absorption and bone health, but it is not directly related to gallbladder function. Enterokinin (Choice D) is a peptide hormone that affects smooth muscle contractions in the gastrointestinal tract, but it is not specifically responsible for stimulating the gallbladder to release bile.
Where does the major portion of the chemical digestion of lipids occur?
- A. Mouth.
- B. Stomach.
- C. Small intestine.
- D. Large intestine.
Correct Answer: C
Rationale: The correct answer is C: Small intestine. The majority of lipid digestion occurs in the small intestine, where bile and pancreatic lipase are active. Lipids are broken down into fatty acids and glycerol in the small intestine. Choices A, B, and D are incorrect because the mouth and stomach play minor roles in lipid digestion, and the large intestine is mainly responsible for absorbing water and electrolytes from the indigestible food residues.
Which lipoprotein carries fat from a meal just consumed to the liver?
- A. Very low-density lipoprotein (VLDL).
- B. Low-density lipoprotein (LDL).
- C. Chylomicrons.
- D. High-density lipoprotein (HDL).
Correct Answer: C
Rationale: Chylomicrons are the lipoproteins responsible for transporting dietary fat from the intestines to various tissues, including the liver. VLDL carries lipids synthesized in the liver, LDL transports cholesterol to tissues, and HDL helps transport cholesterol away from tissues to the liver for excretion. Therefore, in the context of carrying fat from a meal just consumed to the liver, chylomicrons are the correct choice.
How can cholesterol absorption be decreased?
- A. Vitamin K.
- B. Plant sterols.
- C. Trans fats.
- D. Phospholipids.
Correct Answer: B
Rationale: The correct answer is B: Plant sterols. Plant sterols can reduce cholesterol absorption by competing with cholesterol for absorption sites. Vitamin K, choice A, does not have a significant impact on cholesterol absorption. Trans fats, choice C, are known to increase cholesterol levels rather than decrease absorption. Phospholipids, choice D, play a role in cell structure and are not directly involved in reducing cholesterol absorption.
Protein is constantly being exchanged between which two components?
- A. tissue and plasma.
- B. the liver and the small intestine.
- C. blood and lymph.
- D. the heart and lungs.
Correct Answer: A
Rationale: The correct answer is 'tissue and plasma.' Protein turnover involves the continuous exchange of proteins between body tissues and the bloodstream (plasma) as part of normal metabolic processes. This process ensures a balance in protein levels throughout the body. Choices B, C, and D are incorrect as they do not represent the primary sites for protein turnover in the body.
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