Explain how scientists have deduced that life on Earth began 3.9 bya

All but one describes an effect of aging on the digestive system. a) decreased acid secretion b) decreased elasticity of stomach c) capacity to resist damage decreases d) food remains in stomach for less time

Examine the air pressure map. which type of line is shown on the map?

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