1. (Biochemistry) the sum total of the chemical processes that occur in living organisms, resulting in growth, production of energy, elimination of waste material, etc. 2. (Biochemistry) the sum total of the chemical processes affecting a particular substance in the body: carbohydrate metabolism; iodine metabolism.
It is found only in cultivation, where it is the most commonly grown of all plants in the Nicotiana genus, and its leaves are commercially grown in many countries to be processed into tobacco.It grows to heights between 1 to 2 metres.he concentration of nicotine increases with the age of the plant. Tobacco leaves contain 2 to 8% nicotine combined as malate or citrate. The distribution of the nicotine in the mature plant is widely variable: 64% of the total nicotine exists in the leaves, 18% in the stem, 13% in the root, and 5% in the flowers.
Where did tobacco originate from? We already know that processed tobacco comes from the tobacco plant, most commonly Nicotiana tabacum. Plants from the Nicotiana family originated from both North and South America, Australia, Africa and the South Pacific. However, the tobacco that is most commonly grown as a cash crop today originated in the Americas where it had long been cultivated and used by the native people. Christopher Columbus was the first European to be introduced to the plant on his first voyage to the New World.