Fungi have life cycles that are predominantly in which ploidy stage?

Fungi have life cycles that are predominantly in which ploidy stage?

• A. Diploid
• B. Haploid
• C. Triploid
• D. Polyploid

Answer: (B)

Fungi spend most of their life as haploid. Their vegetative forms—hyphae and, in yeasts, the growing cells—carry a single set of chromosomes. Sexual reproduction brings two haploid nuclei together to form a diploid zygote, but that diploid stage is brief; it quickly undergoes meiosis to produce haploid spores, which restart the cycle. Some fungi show a long-lasting dikaryotic stage, where two distinct haploid nuclei share the same cell, but this is not a true diploid state. Because the organism’s cells are typically haploid for the majority of the life cycle, haploid is the best description.

Fungi spend most of their life as haploid. Their vegetative forms—hyphae and, in yeasts, the growing cells—carry a single set of chromosomes. Sexual reproduction brings two haploid nuclei together to form a diploid zygote, but that diploid stage is brief; it quickly undergoes meiosis to produce haploid spores, which restart the cycle. Some fungi show a long-lasting dikaryotic stage, where two distinct haploid nuclei share the same cell, but this is not a true diploid state. Because the organism’s cells are typically haploid for the majority of the life cycle, haploid is the best description.