One theory of early life on Earth states that the first life forms did not use oxygen for respiration and were unable to make their own food. Based on this theory, which types of organisms were most likely present? aerobic, autotrophic bacteria

aerobic, heterotrophic bacteria

anaerobic, autotrophic bacteria

anaerobic, heterotrophic bacteria

if your own plato the answer is b. the fern transitioned from sporophyte generation to gametophyte generation.

genetic variation can be caused by mutation (which can create entirely new alleles in a population), random mating, random fertilization, and recombination between homologous chromosomes during meiosis (which reshuffles alleles within an organism's offspring).

layer 3 is younger than layer 6.