A school aquarium full of Euglena is green in the sunny laboratory.
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A school aquarium full of Euglena is green in the sunny laboratory. During the holidays it is kept in a dark storeroom for two weeks, and the Euglena are still alive. How did they get food in the light, and how in the dark? What does this tell us about kingdom Protista?
Need a reminder? The key ideaShow
Kingdom Protista holds the single-celled eukaryotes. Chrysophytes (diatoms) have walls of silica in two shells and form diatomaceous earth. Dinoflagellates have cellulose plates and two flagella; red ones such as Gonyaulax cause red tides. Euglenoids have a protein pellicle, no wall, and make food in light but eat in the dark. Slime moulds are saprophytes that form a plasmodium and spores.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Step 1. In the light. Euglenoids have the same pigments as higher plants, so they make food by photosynthesis.
Step 2. In the dark. They feed on other small organisms, like heterotrophs.
Step 3. Protista. A protist can live like a plant at one time and like an animal at another. So the kingdom links the plants, the animals and the fungi.
Answer: photosynthesis in light, feeding on small organisms in the dark; protists are a connecting link between kingdoms.
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