Question

Compare Figure 31.5 with Figure 13.6. In terms of haploidy versus diploidy, how do the life cycles of fungi and humans differ?

Short answer

A major part of the entire life cycle of a fungus is spent in the haploid stage. In contrast, in the case of humans, they spend most of their entire life cycle in the diploid stage.

Diploid cells develop during the stages of mitosis. In contrast, haploid cells develop during meiosis.

Step-by-step solution

Step: 1 Diploid human and fungus cells

Human beings are entirely composed of diploid cells, but the sperm cells or egg cells are the only haploid cells. Human beings have 23 pairs of chromosomes in every diploid cell. From 46 chromosomes, two are sex chromosomes.

During the life cycle of a fungus, the zygote is the only diploid cell. Except for the zygote, most of the structures are haploid. In humans, gametes are known as the haploid cells that have 23 chromosomes.

Diploid and haploid cells

The term diploid cells indicate a cell type with two chromosome sets coming from each parent (one from the father and another from the mother). Haploid cells have only one chromosome set, and organisms that asexually reproduce are diploid.

Lifecycles of humans and fungus

In the life cycle of a fungus that reproduces sexually, the haploid phase will be alternated in the diploid phase. Their haploid stage ends with the nuclear fusion, and the zygote formation starts their diploid phase.

Meiosis is a cycle where diploid cells produce haploid cells, and fertilization is the fusion of two haploid cells (male & female gametes) that produces a diploid zygote.