The answer to this question is "neutral stimulus". In Pavlov's studies on the classical conditioning, the bell was a neutral stimulus before it was paired with the food and conditioned stimulus occurred after the conditioning level. The study shows that the bell has a mental connection before it is being paired with the food.
D. Phosphorus. Hope this helped and that it was right :p
The deserts are the regions of the lands, where there is a little precipitation and the temperature is generally too high during the day.
In the desert biome, the animals are adapted to dissipate heat to the environment, which make them remain cooler in the hot days. They have long appendages and long extremities, such as hear, which help them in constantly transferring the heat in their surrounding. Some animals lack fur, which allow them to remain cool, as the presence of fur would not allow the dissipation of the heat to the atmosphere.
The tundra biome is very cold, and the animals living there must have the tendency to trap heat to remain hot in the cold climate. All the desert animals are adapted to dissipate heat to the environment, so, they cannot trap heat, which makes them unfit survive in colder climates.
