Select all of the answers that apply. which of the following events define the proterozoic eon? 1.eukaryotic cells first seen 2.stable continents 3.first bacterial fossils 4.cambrian explosion 5.oxygen builds up in atmosphere

both male and female gametes are produced by meiosis of the germ cells. therefore, both male and female gametes are haploid. one male and one female gamete unite during the fertilization to form the diploid zygote. in seed bearing plants, pollen grain is the male gametophyte, which produces sperm cells.