There was no sunlight, in one way or another sunlight is the source of almost all life on the surface of the earth
<span>The tone, before conditioned to salivation, is simply a stimuli that the dog is responding to or ignoring in it's environment. Since it has no taught reactions to this sound, it is simply part of the environment the dog is in.</span>
The bodies immune response includes all of those cells to help destroy pathogens that wish to bestow havoc on the beautiful homeostasis of the body.
Matter is anything that has mass. everything has matter, even the air.
