The ___ era had many extinctions because of large variations in climate A. Mesozoic
B. Precambrian
C. Paleozic
D. Cenozoic

Science A P E X

Factors that can increase mutation rates a. high temps b. low temps c. food additives d. uv rays

Which is an important function of normal flora? a. aid with bone marrow production. b. crowd out pathogenic bacteria. c. destroy digestive track pathogens. d. manufacture iron in the bloodstream.

How can scientists use the fossil record to find evidence of relationships between different species?