Protists and Fungi: Quick Revision

A brief note on Protists and Fungi. Try each question at the end before you open its answer.

Kingdom Protista: single-celled eukaryotes

Protozoans: heterotrophic protists

Amoeboid (pseudopodia, Amoeba), flagellated (Trypanosoma, sleeping sickness), ciliated (cilia and a gullet, Paramecium), sporozoans (spore-like infectious stage, Plasmodium, malaria).

Kingdom Fungi

• A mycelium of hyphae, septate or coenocytic; yeast is single-celled. Wall of chitin and polysaccharides.
• Saprophytes, parasites or symbionts (lichens, mycorrhiza).
• Spores: asexual (conidia, sporangiospores, zoospores); sexual (oospores, ascospores, basidiospores).
• Sexual cycle: plasmogamy ($n + n$), karyogamy ($2n$), meiosis ($n$).

A worked example

A white fluffy mould on a damp plank has hyphae with no cross walls and many nuclei. Black round sporangia sit on upright hyphae.

1. No cross walls, many nuclei. The mycelium is aseptate and coenocytic.
2. Spores inside sporangia. Asexual spores made inside, as in the Phycomycetes.
3. So it is a phycomycete, like Mucor or Rhizopus.

Practice with new numbers

A program to try

The program is a key to the classes of fungi, used on four fungi.

Mistakes to avoid

• Giving euglenoids a wall. They have a pellicle.
• Mixing up the two parasites. Plasmodium: malaria. Trypanosoma: sleeping sickness.
• Swapping plasmogamy and karyogamy. Cytoplasm first, nuclei second.
• Putting yeast in Basidiomycetes. Yeast is a sac fungus, an ascomycete.

Check yourself

1. How does a euglenoid differ from a diatom in its covering?

2. Name the four groups of protozoans.

3. What are the three steps of the sexual cycle of a fungus?

4. Give one example each of a parasitic and a symbiotic fungus.