State the genus of this organism.

State the domain in which it is classified.

Outline the method of nutrition carried out by P. caudatum.

Outline one aspect of how P. caudatum carries out homeostasis.

Apart from the ribosomes, explain the evidence for the endosymbiotic theory of the origin of eukaryotic cells.

Paramecium

eukaryotes

heterotroph/consumer as it feeds on bacteria/algae/yeast/smaller single celled organisms
OR
heterotroph/consumer as it does not have chloroplasts

Heterotrophic must be qualified.

a. lives in fresh water so water enters cell (by osmosis);

b. contractile vacuoles collect and expel water;

c. homeostasis is keeping internal conditions within limit/constant / involves osmoregulation/regulating water content/potential;

a. mitochondria/chloroplasts show features in common with prokaryotes/similar size;

b. multiply by binary fission/in same manner;

c. have naked loop of DNA/circular DNA/own DNA;

d. surrounded by a double membrane;

In a about half of the candidates named the genus correctly (Paramaecium), but significantly fewer could state the correct domain (eukaryota). The most common wrong answers were prokaryote and eubacteria. Only the better candidates were able to outline the method of nutrition (heterotrophy) in b and describe how homeostasis is carried out, in spite of being specifically stated in the syllabus. The endosymbiotic theory was quite well known.