Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
Diplontic organisms spend the majority of their life cycle in the diploid state, where cells contain two sets of chromosomes. This is contrasted with haplontic life cycles, where the majority of the life cycle is spent in the haploid state.
5 Must Know Facts For Your Next Test
Diplontic life cycles are common in animals and some algae.
The diploid phase produces gametes through meiosis.
Fertilization between gametes restores the diploid chromosome number.
In diplontic organisms, mitosis occurs only in the diploid phase.
Seedless plants such as ferns exhibit a dominant sporophyte (diploid) phase.
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Related terms
Haplontic: Life cycle primarily in the haploid state with a short-lived diploid phase.
Sporophyte: The diploid generation that produces spores via meiosis in plants.
Gametophyte: The haploid generation that produces gametes through mitosis in plants.