Which of the following statements characterizes irritable bowel syndrome?

Correct Answer: C

Rationale: Irritable bowel syndrome (IBS) is a gastrointestinal disorder characterized by abdominal pain, bloating, and changes in bowel habits. While IBS can lead to symptoms like diarrhea or constipation, it typically does not cause anemia (choice A), is not generally associated with intestinal E. coli (choice B), and is not often associated with bloody diarrhea (choice D). However, IBS can indeed be associated with anxiety and/or depression (choice C) due to the gut-brain axis, a bidirectional communication system between the gut and the brain. This association is well-documented in IBS patients, highlighting the importance of considering psychological factors in managing the condition.

Correct Answer: A

Rationale: Psoriasis is the correct answer because it is a chronic inflammatory skin condition characterized by features such as angiogenesis (formation of new blood vessels), immune cell activation (especially T cells), and excessive keratinocyte proliferation. This results in the typical symptoms seen in psoriasis, such as red, scaly patches on the skin. Melanoma is a type of skin cancer arising from melanocytes, not characterized by the features mentioned. Atopic dermatitis is a different skin condition involving eczematous changes, not specifically associated with the described characteristics of psoriasis. Urticaria is a skin condition characterized by hives and does not involve the same pathophysiological processes as psoriasis.

Correct Answer: A

Rationale: The correct answer is A. In active transport, energy is expended to move substances against their concentration gradient. Sodium moving out of cells and potassium moving into cells is an example of active transport because it requires energy to pump these ions across the cell membrane against their concentration gradients. Choices B, C, and D describe passive processes where substances move along their concentration gradients without the input of energy.

Correct Answer: C

Rationale: The correct answer is 'genetically modified food.' Canola oil derived from genetically modified canola plants falls into this category because the plant's genome has been altered to exhibit herbicide resistance. This genetic modification makes it a genetically modified food. Choice A, 'pesticide-free food,' is incorrect as the genetic modification is to resist herbicides, not pesticides. Choice B, 'saturated fat food,' is incorrect as it does not accurately describe the genetic modification of the canola plants. Choice D, 'product that is pure,' is too vague and does not address the genetic modification aspect of the canola plants.

Correct Answer: A

Rationale: In this scenario, the correct answer is the 55-year-old man with new onset headaches that worsen at night and reported mood swings according to his family. These symptoms, especially when combined with nighttime worsening and mood changes, could indicate a serious underlying disorder such as a brain tumor or increased intracranial pressure. Choice B is incorrect as the unilateral throbbing headache with photophobia and nausea is suggestive of migraine headaches, which are usually not associated with serious underlying disorders. Choice C describes symptoms that are more indicative of tension-type headaches rather than a serious underlying disorder. Choice D presents symptoms that are more likely related to hormonal changes and migraines rather than a serious underlying disorder.

Correct Answer: D

Rationale: Anemia of chronic inflammation is typically characterized by normochromic (normal hemoglobin content) and normocytic (normal cell size) red blood cells. Choice A, hypochromic and microcytic, is incorrect because hypochromic refers to reduced hemoglobin content and microcytic refers to smaller than normal red blood cells, which are not typically seen in anemia of chronic inflammation. Choice B, hypochromic and macrocytic, is also incorrect as macrocytic refers to larger than normal red blood cells. Choice C, normochromic and microcytic, is incorrect because microcytic red blood cells are smaller than normal. Therefore, the correct classification for anemia of chronic inflammation is normochromic and normocytic.

Correct Answer: D

Rationale: The correct answer is that ductal carcinoma in situ is characterized by malignant cells that have not invaded the stroma, making it a cancer precursor with a higher risk for invasive cancer compared to lobular carcinoma in situ. Choice A is incorrect because ductal carcinoma in situ is more common than lobular carcinoma in situ. Choice B is incorrect as it only partially describes ductal carcinoma in situ without mentioning its potential for progression to invasive cancer. Choice C is incorrect because it does not capture the complete characteristics of ductal carcinoma in situ, which include the risk for invasive cancer.

Correct Answer: D

Rationale: Women with breast cancer due to a BRCA1 gene mutation commonly have a triple-negative breast cancer subtype, which means they are negative for estrogen receptor, progesterone receptor, and human epidermal growth factor receptor 2 (HER2). This subtype tends to be more aggressive and harder to treat. Choice A is incorrect as they are typically negative for HER2. Choice B is incorrect because they are usually negative for estrogen receptor. Choice C is incorrect as they are usually negative for progesterone receptor and HER2.

Correct Answer: C

Rationale: The correct answer is C: Decline in kidney function. As people age, their kidneys may not work as effectively in conserving water and concentrating urine, leading to a higher risk of dehydration. Choice A is incorrect because more insensible losses do not directly relate to an increased risk of dehydration in the elderly. Choice B, an increase in muscle mass, is not a factor that leads to dehydration. Choice D, a decrease in fat, is also not a direct factor contributing to dehydration in the elderly.