Not necessarily. A zygote is a cell formed by the union of two gametes and will have two or more sets of chromosomes. Depending on the ploidy of the two gametes, the zygote can be any ploidy above haploid, even an odd number. In humans, each gamete is haploid; therefore a human zygote is diploid. However, other organisms, particularly plants, may have diploid, triploid, tetraploid, etc. Gametes resulting in zygotes will double these ploidies. Examples of tetraploid organisms include potatoes and peanuts. A triploid zygote can arise from the union of a diploid and a haploid gamete. Most triploid zygotes are sterile, however. Examples of triploid organisms include seedless watermelons and seedless grapes.