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.
It is a green, leafy plant. In the United States the states where most tobacco is grown is within Virginia, Kentucky and central Tennessee. Some examples of Types of tobacco and where they are grown: Brightleaf tobacco, Brightleaf is commonly known as Virginia tobacco, often regardless of which state they are planted.Prior to the American Civil War, most tobacco grown in the US was fire-cured dark-leaf.riental tobacco, is a sun-cured, highly aromatic, small-leafed variety (Nicotiana tabacum) that is grown in Turkey, Greece, Bulgaria, and Macedonia.