The above picture shows the main organ involved in

Correct Answer: A

Rationale: The correct answer is A: excretion. The organ shown is the kidney, which plays a vital role in filtering waste products from the blood to form urine for excretion. It is not involved in digestion (B), reproduction (C), or combating foreign microbes (D). Kidneys are specifically designed for excretion, making choice A the correct answer.

Correct Answer: D

Rationale: The correct answer is D: Carbon dioxide. The UREA breath test measures the presence of H. pylori in the stomach by detecting the breakdown of urea into carbon dioxide and ammonia by the bacteria. H. pylori produces the enzyme urease, which hydrolyzes urea into ammonia and carbon dioxide. Therefore, an increase in carbon dioxide levels indicates the presence of H. pylori. Choice A (Ammonia) is incorrect because the test does not specifically measure ammonia levels. Choice B (Urea) is also incorrect because the test measures the breakdown of urea, not the urea itself. Choice C (Hydrochloric acid) is incorrect as the test does not directly measure this acid.

Correct Answer: C

Rationale: The correct answer is C: Helicobacter pylori infection. This bacterium is the most common cause of peptic ulcer disease by causing inflammation and weakening the protective lining of the stomach or duodenum. Studies have shown a strong association between H. pylori infection and peptic ulcers. A high-fat diet (A) may exacerbate symptoms but is not the primary cause. Stress (B) and alcohol consumption (D) can worsen symptoms but do not directly cause peptic ulcers. In summary, H. pylori infection is the leading cause of peptic ulcer disease due to its ability to damage the stomach lining.

Correct Answer: D

Rationale: The correct answer is D because the term mucosa (mucous membrane) refers to the moist surface lining of any hollow organ that communicates with the outside world. This includes organs like the respiratory tract, gastrointestinal tract, and genitourinary tract. The mucosa serves various functions such as protection, absorption, and secretion. Explanation for why the other choices are incorrect: A: A nonkeratinized stratified squamous epithelium describes a specific type of epithelium found in certain areas of the body, but it does not encompass the full definition of mucosa. B: While mucosa may contain mucus-secreting goblet cells, this is not the defining characteristic of mucosa. C: Mucous glands may secrete their product onto the mucosa, but this definition is too specific and does not encompass the full scope of mucosa.

Correct Answer: C

Rationale: The correct answer is C: larger blood vessels. The submucosa is a layer of connective tissue deep to the mucosa, which contains larger blood vessels that supply nutrients to the mucosa and surrounding tissues. This is essential for the maintenance of tissue health and function. The other choices are incorrect because: A: The presence of white blood cells does not differentiate the submucosa from the lamina propria. B: Both the submucosa and lamina propria contain lymphatic tissue, so the amount of lymphatic tissue does not differentiate them. D: Collagen fibers are present in both the submucosa and lamina propria, so the thickness of collagen fibers is not a distinguishing factor.