Biological Life Cycle

Biological Life Cycle

A life cycle is a period involving all different generations of a species succeeding each other through means of reproduction, whether through asexual reproduction or sexual reproduction (a period from one generation of organisms to the same identical). For example, a complex life cycle of Fasciola hepatica, a parasitic flatworm, includes three different multicellular generations: 1) "adult" hermaphroditic; 2) sporocyst; 3) redia.

In regard to changes of ploidy, there are 3 types of cycles:

  • haplontic life cycle
  • diplontic life cycle
  • diplobiontic life cycle (also referred to as diplohaplontic, haplodiplontic, or dibiontic life cycle)

These three types of cycles feature alternating haploid and all germinates. To return to a haploid stage, meiosis must occur (see Cell division). The cycles differ in the product of meiosis, and whether mitosis (growth) occurs. Zygotic and gametic meioses have one mitotic stage and form: during the n phase in zygotic meiosis and during the 2n phase in gametic meiosis. Therefore, zygotic and gametic meiosis are collectively term haplobiontic (single mitosis per phase). Sporic meiosis, on the other hand, has two mitosis events (diplobiontic): one in each phase.

Read more about Biological Life Cycle:  Haplontic Life Cycle, Diplontic Life Cycle, Haplodiplontic Life Cycle, Life History, Life History Theory

Other articles related to "biological life cycle, life":

Biological Life Cycle - Life History Theory
... In animal and human biology, life history theory is a method of understanding evolved behaviors and strategies to optimize reproductive success ...

Famous quotes containing the words cycle, biological and/or life:

    The lifelong process of caregiving, is the ultimate link between caregivers of all ages. You and I are not just in a phase we will outgrow. This is life—birth, death, and everything in between.... The care continuum is the cycle of life turning full circle in each of our lives. And what we learn when we spoon-feed our babies will echo in our ears as we feed our parents. The point is not to be done. The point is to be ready to do again.
    Paula C. Lowe (20th century)

    In America every woman has her set of girl-friends; some are cousins, the rest are gained at school. These form a permanent committee who sit on each other’s affairs, who “come out” together, marry and divorce together, and who end as those groups of bustling, heartless well-informed club-women who govern society. Against them the Couple of Ehepaar is helpless and Man in their eyes but a biological interlude.
    Cyril Connolly (1903–1974)

    The great passion in a man’s life may not be for women or men or wealth or toys or fame, or even for his children, but for his masculinity, and at any point in his life he may be tempted to throw over the things for which he regularly lays down his life for the sake of that masculinity. He may keep this passion secret from women, and he may even deny it to himself, but the other boys know it about themselves and the wiser ones know it about the rest of us as well.
    Frank Pittman (20th century)