Question

Animals, including humans, are characterized by a diplontic life cycle: non-reproductive cells (somatic) are diploid and only the sexual cells (gametes) are haploid. During embryonic development and growth, diploid cells divide via mitosis. However, not all multicellular organisms are diplontic. For instance, fungi are haplontic. All cells in fungi are haploid; during sexual reproduction, a cell from a (+) individual interacts with a cell from a (−) individual allowing nuclear fusion, forming a diploid zygote. This diploid zygote divides by meiosis forming 4 haploid spores (when these spores germinate, they will produce a (+) or (−) multicellular fungi). You guessed it right! It's exactly the opposite compared to animals! All cells in fungi are haploid, except for the zygote, which is diploid. Explain the meaning of haploid and diploid. Use your own words.

Answer 1

Haploid cells (1n) have a single set of chromosomes, while diploid cells (2n) have two sets, one from each parent. Fungi primarily exhibit a haploid life cycle, with a brief diploid phase forming a zygote that undergoes meiosis to produce haploid spores.

Step-by-step explanation:

The terms haploid and diploid are used to describe the number of chromosome sets found in the nucleus of a cell.

• Haploid cells (1n) contain a single set of chromosomes, and this is the form seen in the gametes (sperm and egg cells) of animals.
• Diploid cells (2n) have two sets of chromosomes, one from each parent, and this arrangement is seen in somatic (non-reproductive) cells of animals.

In the case of fungal organisms, their life cycle is mostly haploid, where cells reproduce by mitosis and maintain the haploid state. During sexual reproduction, two specialized haploid cells (+ and - mating types) fuse to form a diploid zygote which then undergoes meiosis to produce haploid spores that will grow into a new multicellular haploid fungus.