The stimulus is a physical entity, which can provoke the response in the body of an organism. The hiding of the organism under the rock in response to the predator is and a type of external stimuli, as in this case, the organisms hide themselves inside the rock in response to the predator, which is present outside the body of the organism.
All the factors listed, that is population density, temperature, carrying capacity, rainfall and sunlight all effect the living conditions of organisms in a biome as well as the type of species that will be found there.
