5. The atmosphere of early Earth is unlike today's atmosphere. A. When did oxygen first appear in Earth's early atmosphere? (3 points)

B. What factor caused the appearance of oxygen? (3 points)

C. What is one form of evidence used to support this theory? (4 points)

Whenever diploid populations are in hardy-weinberg equilibrium at a particular locus a) the allele's frequency should not change from one generation to the next, but its representation in homozygous and heterozygous genotypes may change. b) natural selection, gene flow, and genetic drift are acting equally to change an allele's frequency. c) this means that, at this locus, two alleles are present in equal proportions. d) the population itself is not evolving, but individuals within the population may be evolving.