10-17-2015, 08:26 PM
(10-15-2015, 06:55 PM)PhilHos Wrote: Not a single one of those state that gametes are a stage of development. They do show what I've already said and that is that gametes are a PART of a stage of human development.
Not a single one of those state a zygote or an adult human is a stage of development, but they are. Because the diagrams show the stages of development for people who don't understand words. Like the words in post #546 . . .
Quote:Life cycles that include sexual reproduction involve alternating haploid (n) and diploid (2n) stages, i.e., a change of ploidy is involved. To return from a diploid stage to a haploid stage, meiosis must occur. In regard to changes of ploidy, there are 3 types of cycles:
- haplontic life cycle — the haploid stage is multicellular and the diploid stage is a single cell, meiosis is "zygotic".
- diplontic life cycle — the diploid stage is multicellular and haploid gametes are formed, meiosis is "gametic".
- haplodiplontic life cycle (also referred to as diplohaplontic, diplobiontic, or dibiontic life cycle) — multicellular diploid and haploid stages occur, meiosis is "sporic".