Quick Quiz: Nouns Score: Change category, Flip order Reset Incorrect! Try again. Noun: citric acid cycle Your choice? in all plants and animals: a series of enzymatic reactions in mitochondria involving oxidative metabolism of acetyl compounds to produce high-energy phosphate compounds that are the source of cellular energy semiprecious yellow quartz resembling topaz   (Noun: citrine) a city in northwestern Belgium in West Flanders province; connected by canal to the North Sea; the old city is a popular tourist attraction ordinary clothing as distinguished from uniforms, work clothes, clerical garb, etc.