The condition characterized by an enlarged thyroid gland due to dietary iodine deficiency is: MCQ with Answer and Explanation

Explanation:
Peptide YY (PYY) is a gut hormone secreted by the L cells in the mucosa of the distal small intestine (ileum) and colon, primarily in response to food ingestion, especially fats. Its primary functions are related to the 'ileal brake' mechanism: it inhibits gastric emptying and pancreatic exocrine secretion, slowing down the transit of food through the upper GI tract to allow more time for digestion and absorption in the ileum. It also acts on the hypothalamus to reduce appetite, serving as a satiety signal.

Explanation:
Hydrophily is pollination by water and occurs in aquatic plants like Vallisneria and Zostera. Terrestrial plants do not use water for pollination. All other statements are correct.

Explanation:
Alveoli are tiny, thin-walled air sacs surrounded by pulmonary capillaries. Oxygen diffuses across the alveolar and capillary walls into the blood, while CO₂ diffuses out. The trachea, bronchi, and nasal cavity are air passages that do not participate directly in gas exchange.