Some organisms have a large geographic range. For example, the Norway rat lives on every continent except Antarctica. A population of Norway rats is the number of rats in one particular area. Do you think it’s scientifically possible for a population of Norway rats in North America to carry different genetic mutations than a population of Norway rats in Africa? Do you think it’s possible that they carry some of the same mutations? What types of information can scientists learn by studying the genomes of these two populations of rats?

Juan and carol were studying invertebrates in biology. they knew that segmented or earth worms preferred a dark, moist habitat. during this lab, they would be investigating the responses of organisms called planaria or dugesia tigrina. these were simple flatworms that still had a one-way digestive system and a very simple nervous system. juan and carol placed the planaria in a petri dish containing cool, distilled water that was partially covered with black paper. they shined a light on the dish. next, they removed the paper and placed a small amount of chicken liver at one end of the dish. they added a few large salt crystals to the water. finally, they added drops of hot water to the cool water in the petri dish. their results can be seen in the data table. according to their experiment, all but one conclusion is valid.