Identify the ODD term in each set and name the CATEGORY to which the remaining three belong. Example: glucose, starch, cellulose, calcium — Odd term: calcium; Category: the others are different types of carbohydrates.
Insulin, Adrenaline, Pepsin, Thyroxine.
Topic: Hormones
Answer
Odd term: PEPSIN. Category of the others: HORMONES.
Insulin, adrenaline and thyroxine are all HORMONES — chemical messengers secreted by ductless glands directly into the blood and carried to distant target organs.
PEPSIN is an ENZYME, a biological catalyst secreted by the gastric glands of the stomach to digest proteins.
THE DISTINCTION worth stating, since it is examined in its own right: HORMONES are carried in the BLOOD, act at a DISTANCE, and are USED UP in the reaction ENZYMES act at the SITE where they are secreted, and are NOT used up — a catalyst is recovered unchanged
A useful clue in the names: most enzymes end in -ASE or, like pepsin and trypsin, in -IN following an older convention.