Ivan pavlov, a russian repeatedly exposed dogs to the sight of food and, at the same time, the sound of a at first, the dogs salivated because of the food; this reaction is known as but after a while, the dogs begin to salivate when they heard the sound, even if no food was present. this learned reaction is known as and the sound is called a

Based on the data in your tables, did the light-colored moths have a higher or lower survival rate after the industrial revolution?

All eukaryotic cells contain small bodies called

Which of the following statements is true about the relationship between genetic variation and natural selection? a. genetic variation must be present in a population before natural selection can act on it. b. genetic variation arises in a population as a result of natural selection. c. natural selection can act on a population whether there is genetic variation within the population or not. d. after natural selection acts on a population, the amount of genetic variation in the population always increases.