Answers to the "Blasts from the Past" questions may be similar to the following: Organisms live in both and the ecosystems are found within the biosphere. Both are ways that scientists answer questions. A hypothesis is smaller in scale than a theory beacuse it requires one experiment while a theory relys on many. Both are part of a controlled experiment. The independent variable is what is changed or manipulated while the constant in unchanged. What is natural selection, a concept of evolution, based upon? In what form do some scientists record their observations? What is the sequence of DNA is refered to as?