The term 'binomial nomenclature' was first introduced by: MCQ with Answer and Explanation

Explanation:
Phenylketonuria (PKU) is an autosomal recessive disorder due to deficiency of phenylalanine hydroxylase, leading to accumulation of phenylalanine, causing mental retardation if untreated. Albinism is tyrosinase deficiency, sickle cell HbS mutation, cystic fibrosis CFTR defect.

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:
The pancreas acts as an exocrine gland (secreting digestive enzymes into the duodenum) and an endocrine gland (secreting insulin and glucagon into blood). The liver has metabolic but not major endocrine function, spleen is lymphoid, gall bladder stores bile.