代谢

replacement / substitution / metabolism (biol.)

to substitute / to act on behalf of others / to replace / generation / dynasty / age / period / (historical) era / (geological) eon

to thank / to apologize / (of flowers, leaves etc) to wither / to decline

metabolism (biology) / the new replaces the old (idiom)

energy metabolism

catabolism (biology) / metabolic breaking down and waste disposal / dissimilation

(medicine) tyrosinosis

pharmacokinetics

anabolism (biology) / constructive metabolism (using energy to make proteins etc) / assimilation