The atmosphere exerts a force (pressure) on earth. why does the atmosphere exert pressure on earth?
a. because of the weight of air
b. because of the ozone layer
c. because of energy from the sun
d. because of the greenhouse effect

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