Identify one of the key external difference between vertebrates and invertebrates. a) vertebrates are always radial symmetrical. b) invertebrates are always bilaterally symmetrical. c) invertebrates are always bilaterally symmetrical, while vertebrates could show either bilateral or radial symmetry. d) vertebrates are always bilaterally symmetrical, while invertebrates could show either bilateral or radial symmetry.

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.