The growth of many fungi, yeasts, bacteria, and viruses was inhibited by tannins. Tannins are found in many of the foods you eat, including fruits, teas, wine and edible grasses -- like corn. Tannin blocks the orifices of tiny cells in the body, which absorbs nutrient from eaten food.
The JFET is a Voltage Operated Transistor. In the N channel device, the N channel is sandwiched between two P type regions (the gate and the substrate) that are connected together electrically to form the gate. The N type channel is connected to the source and drain terminals via more heavily doped N+ type regions.
The bias is the operating point. For a bipolar transistor (BJT) the bias resistor will maintain enough current into the base so that the transistor is neither saturated (fully on) or cut-off (fully off). Some BJTs come with an internal bias resistor to reduce the parts count in a design.