What are the two gases that animals exchange and their surroundings
a. oxygen and nitrogen
b. nitrogen in helium
c. hydrogen and carbon dioxide
d. corbin the outside and oxygen

The idea of spontaneous generation was disproved by in a experiment involving jars of meat

Use the phylogenetic tree to the right to determine which statement below is true. organisms a and f are not related. organism e is more closely related to organism b than organism f. organisms c and d are more closely related than organisms a and b. phylogenetic trees

About how many years does it take for one cycle of surface water to become deep water and then surface water again in the oceans? 101001,000