Final answer:
A diploid zygote immediately undergoes meiosis in a haplontic life cycle, where the zygote develops directly into adults without any intervening diploid stage.
Step-by-step explanation:
When a diploid zygote immediately undergoes meiosis, the life cycle is haplontic. In a haplontic life cycle, the zygote undergoes meiosis to produce haploid cells, which then directly develop into adults. This occurs in many algae, fungi, and some protists.
Learn more about Haplontic life cycle