Plant cells have and which are not present in animal cells.
a. mitochondria, chloroplasts
b. cell membranes, cell walls
c. chloroplasts, nucleus
d. chloroplasts, cell walls

If many different species live in an ecosystem, this the ecosystem to fill its a. populations b. niches c. producers d. communities

How can a geological time scale best be reconstructed? a) comparing vestigial structures in living species b) comparing homologous structures in living species c) examining homologous structures in fossil remains d) examining the written records of scientists from past cultures

Guinea pig coat color is determined by a single gene. the allele for black coat color is dominant to brown. in a cross between twoblack-haired guinea pigs, 20 offspring are born. if both parents were heterozygous, probability would predict that approximately howmany of the 20 offspring would have brown hair?