Fungi: Structure and Reproduction

Fungi

• Fungi are heterotrophic, meaning they cannot produce their own food.
• They use absorptive nutrition, absorbing nutrients from their environment.
• Most fungi are multicellular, but there are also single-celled yeasts.
• Fungi are sessile, meaning they cannot move.
• Fungi have cell walls made of chitin.
• Fungi are closely related to animals and both evolved multicellularity independently.
• Fungi reproduce both sexually and asexually.
• During asexual reproduction, fungal mycelium (haploid, n) produces spores that germinate to form new haploid mycelia.
• During sexual reproduction, plasmogamy (fusion of cytoplasm from two parent mycelia, both haploid, n) occurs, forming an interkaryotic stage with two different nuclei.
• This is followed by karyogamy, the fusion of the nuclei from the two parents, forming a diploid zygote (2n).
• The diploid zygote undergoes meiosis to produce haploid spores.
• These spores then germinate to form new haploid mycelia.
• The mycelium of fungi is made up of tiny filaments called hyphae.
• Hyphae are tubular cell walls surrounding a membrane and cytoplasm.
• The hyphae are interwoven to form mycelium which infiltrates food, maximizing the surface-to-volume ratio for efficient nutrient absorption.
• Fungi absorb nutrients from their environment by osmosis, where water moves into their cells.
• Fungi grow by lengthening their hyphae, not widening them.
• Fungi have spore-producing structures for sexual and asexual reproduction.
• Fungi are decomposers, breaking down and absorbing nutrients from non-living organic materials such as logs and animals.
• Mycorrhizal fungi form mutually beneficial relationships with plant roots, helping plants absorb water and nutrients, while the fungi get food produced by the plant.
• Some fungi are parasitic pathogens that cause diseases in plants and take their nutrients.
• Lichens are symbiotic relationships between fungi and algae or cyanobacteria.
• The fungi provides structure and protection, while the algae or cyanobacteria produce food.

Animals

• Animals are heterotrophic, multicellular, and process food internally.
• Animals do not have cell walls but have nerves and can move, usually.
• Many animals have bilateral symmetry, meaning their body parts are arranged in a mirror image along a central axis.
• Bilateral symmetry helps with directional movement.
• The Cambrian Period saw a significant increase in animal diversity due to the development of predator-prey relationships.
• Some animals have radial symmetry, meaning their body parts are arranged around a central axis.
• Animals with radial symmetry are mostly sessile.
• Diploblastic animals have two layers of cells: ectoderm and endoderm. The ectoderm forms the outer covering and the endoderm lines the digestive tract.
• Triploblastic animals have three layers of cells: ectoderm, mesoderm, and endoderm.
• The mesoderm forms muscles, bones, and other internal organs, leading to more complex animals.
• Animals typically reproduce sexually with a gametic life cycle where diploid cells dominate. The life cycle includes fertilization, meiosis, and mitosis.
• A pseudocoelom is a body cavity that is not fully lined by mesoderm. Nematodes are an example of animals with a pseudocoelom.
• The closest living relative to animals is the choanoflagellate.
• Animals are divided into protosomes and deuterostomes based on developmental differences.

Explore the fascinating world of fungi, including their unique characteristics and reproductive methods. This quiz covers the essential aspects of fungal biology, such as their multicellular nature, cell structure, and life cycle. Test your knowledge of how fungi reproduce both sexually and asexually.