Haploid cells have only one copy of each chromosome. Within higher organisms, only the reproductive cells are haploid, whereas the somatic (body) cells are diploid (two copies of each chromosome) or polyploid (three or more copies of each chromosome, often found in plants).
When reproducing, the haploid sex cells of both parents will generally merge to form a diploid cell the zygote, with unique genetic properties, which will quickly become the embryo.
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