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).
A) Diffusion is a result of the kinetic energy of atoms and molecules. B) Diffusion is driven by concentration gradients. C) Diffusion requires no input of energy into the system. D) Diffusion occurs when particles spread from areas where they are less concentrated to areas where they are more concentrated. E) Diffusion occurs even after equilibrium is reached and no net change is apparent. Answer: D. 12) Diffusion does not require the cell to expend ATP.