Characteristics of Fungi

Free Response

What are the evolutionary advantages for an organism to reproduce both asexually and sexually?

Hint:

Asexual reproduction is fast and best under favorable conditions. Sexual reproduction allows the recombination of genetic traits and increases the odds of developing new adaptations better suited to a changed environment.

Compare plants, animals, and fungi, considering these components: cell wall, chloroplasts, plasma membrane, food source, and polysaccharide storage. Be sure to indicate fungi’s similarities and differences to plants and animals.

Hint:

Animals have no cell walls; fungi have cell walls containing chitin; plants have cell walls containing cellulose. Chloroplasts are absent in both animals and fungi but are present in plants. Animal plasma membranes are stabilized with cholesterol, while fungi plasma membranes are stabilized with ergosterol, and plant plasma membranes are stabilized with phytosterols. Animals obtain N and C from food sources via internal digestion. Fungi obtain N and C from food sources via external digestion. Plants obtain organic N from the environment or through symbiotic N-fixing bacteria; they obtain C from photosynthesis. Animals and fungi store polysaccharides as glycogen, while plants store them as starch.

Why is the large surface area of the mycelium essential for nutrient acquisition by fungi?

Hint:

Fungi break down decaying matter in their environment to serve as their food source. Since the digestion occurs externally, the large mycelium can secrete exoenzymes over a large area. The fungi must be able to absorb the small molecules released by digestion, so having a large surface area increases the amount of digested molecules that are captured by the fungi.