Correct Answer: A

Rationale: Skip lesions are typical characteristics of Crohn's disease, where patches of diseased intestine are interspersed with areas of healthy tissue. This is why option A is the correct answer. Option B, fistulas, are abnormal connections between two body parts, which is not what the question is describing. Option C, fissures, are small tears in the lining of the anus, which also do not fit the description in the question. Option D, loop ulcerations, is not a recognized medical term, making it an incorrect choice.

Correct Answer: B

Rationale: The correct answer is B, Altered taste sensation. The use of antibiotics is known to cause changes in taste sensation as a side effect, especially when used to treat H. pylori infections. Hemoptysis (Choice A) refers to coughing up blood, and while it can be a symptom of various conditions, it is not typically associated with the use of antibiotics. Flatulence (Choice C) and bloody stools (Choice D) can also occur as gastrointestinal complications, but they are not the most likely side effect when treating H. pylori with antibiotics. Therefore, choices A, C, and D are incorrect.

Correct Answer: A

Rationale: Cholesterol is a precursor for the synthesis of sex hormones like estrogen and testosterone.

Correct Answer: A

Rationale: Amino acids are the correct answer because they are the building blocks of proteins that the body absorbs after digestion. Pepsin, choice B, is incorrect as it is an enzyme that aids in the digestion of proteins, not the absorbable unit of them. Choices C and D, glucose and sucrose, are wrong because they are types of sugars, not proteins.

Correct Answer: D

Rationale: Lipids are known for several functions including involvement in energy metabolism and storage (Choice A), providing insulation and protection (Choice B), and acting as hormones that regulate the body (Choice C). However, lipids are not hydrophilic (water-attracting), contrary to choice D. They are actually hydrophobic, meaning they repel water and do not mix well with it. This is a key property that differentiates them from many other biological molecules.