When gametes combine to form a zygote, the chromosomes number of the zygote is now referred to as

When gametes combine to form a zygote, the chromosomes number of the zygote is now referred to as diploid.

Explanation:

The term diploid refers to the complete chromosome charge of a cell, in this case a somatic cell. Sex cells, or gametes, contain only half of the chromosome charge that each parent confers on their offspring, and are called haploid cells.

Two gametes, haploids, each contribute their half of the chromosome charge to form a diploid cell, the zygote.

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Diploid - haploid link