Diffusion is simply the transport of molecules from an area of higher concentration to lower concentration without energy being required from the cell.
Their vision has adapted to be very good, so they can see at night and get small rodents to eat
Active Immunity - antibodies that develop in a person's own immune system after the body is exposed to an antigen through a disease or when you get an immunization (i.e. a flu shot). This type of immunity lasts for a long time.