The Black Death was an epidemic of bubonic plague, a disease caused by the bacterium Yersinia pestis that circulates among wild rodents where they live in great numbers and density. Such an area is called a âplague focusâ or a âplague reservoirâ.
Diffusion is the net movement of molecules or atoms from a region of high concentration to a region of low concentration.his is also referred to as the movement of a substance down a concentration gradient. A gradient is the change in the value of a quantity (e.g., concentration, pressure, temperature) with the change in another variable (usually distance).
Which of the following is required for facilitated diffusion to occur? a) a concentration gradient b) a carrier and concentration gradient c) carrier and energy d)...show more a) a concentration gradient b) a carrier and concentration gradient c) carrier and energy d) vesicles e) vesicle to membrane fusion ALSO!est Answer: First Question: A-a concentration gradient because diffusion is process molecules move down a concentration gradient.