Kathleen is testing a mixture containing a certain substance. She takes a sample from the top and the bottom. The sample from the bottom has more of the substance than the sample from the top. What is this mixture?

Which of these is not an example of molecular homology? 1. use of dna and rna as genetic material 2.use of glycolysis as the first step in cellular respiration in both plants and animals 3. the lack of an igf-1 gene in prokaryotes 4. the use of aldolase b to break down fructose in bacteria, plants and animals