Final answer:
Yeast can reproduce both sexually and asexually. Asexual reproduction occurs through budding, while sexual reproduction involves plasmogamy, leading to diploid zygotes that can undergo meiosis to produce haploid spores.
Step-by-step explanation:
Saccharomyces cerevisiae, commonly known as yeast, can undergo sexual or asexual reproduction to give rise to either haplophase or diplophase. In asexual reproduction, yeast predominantly reproduces via budding, leading to a diploid state if the parent cell was diploid. However, yeast can also reproduce sexually, especially under adverse environmental conditions. Through sexual reproduction, haploid cells of opposite mating types utilize pheromones to find each other and fuse through a process known as plasmogamy, forming a diploid zygote. This diploid state can undergo meiosis to return to the haplophase, producing haploid spores that can germinate and propagate the species.