Fungi are a kingdom of living organisms that includes mushrooms, molds, yeasts, and many microscopic species. They are not plants because they do not make food by photosynthesis. Instead, fungi get nutrients by breaking down or absorbing material from their surroundings.
This makes them essential decomposers in forests, soils, farms, and many food webs.
A mushroom is only the visible reproductive part of a much larger organism hidden in the soil or wood. Most of the fungus is made of thin threads called hyphae, which form a branching network called mycelium. The mycelium releases enzymes that digest food outside the body, then absorbs the smaller molecules.
Fungi reproduce using spores, and many also form helpful partnerships with plant roots that improve nutrient uptake.
Key Facts
- Fungi are eukaryotes, meaning their cells have nuclei and membrane-bound organelles.
- Hyphae are threadlike fungal filaments, and many hyphae together form a mycelium.
- Fungi feed by extracellular digestion: enzymes break down food outside the body, then nutrients are absorbed.
- Mushrooms are fruiting bodies that produce and release spores for reproduction.
- Surface area helps absorption: surface area to volume ratio = surface area / volume.
- Many fungi are decomposers, mutualists, or parasites, depending on how they get nutrients.
Vocabulary
- Fungus
- A eukaryotic organism that absorbs nutrients from its environment and belongs to the kingdom Fungi.
- Hypha
- A thin, threadlike filament that makes up the body of most fungi.
- Mycelium
- A branching network of hyphae that grows through soil, wood, or other material.
- Spore
- A tiny reproductive cell that can grow into a new fungus under suitable conditions.
- Mycorrhiza
- A mutualistic relationship between fungal hyphae and plant roots.
Common Mistakes to Avoid
- Calling fungi plants is wrong because fungi do not photosynthesize and have cell walls made mostly of chitin rather than cellulose.
- Thinking the mushroom is the whole fungus is wrong because the main body is usually the hidden mycelium growing through soil or wood.
- Saying fungi eat by swallowing food is wrong because fungi digest food outside their bodies with enzymes and then absorb nutrients.
- Assuming all fungi are harmful is wrong because many fungi recycle nutrients, help plants grow, and are used to make foods and medicines.
Practice Questions
- 1 A fungus releases 2,500 spores from each gill, and the mushroom has 80 gills. How many spores are released in total?
- 2 A mycelium grows 3.5 cm per day through soil. How far will it grow in 12 days if conditions stay the same?
- 3 Explain why a branching mycelium is better for absorption than one thick fungal strand of the same total mass.