paramecium-3 - radiating channels Other ciliates There are...

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Paramecium 3 Paramecium - Osmoregulation Paramecium and amoeba live in fresh water. Their cytoplasm contains a greater concentration of solutes than their surroundings and so they absorb water by osmosis. The excess water is collected into a contractile vacuole which swells and finally expels water through an opening in the cell membrane. In amoeba, the vacuole forms near the posterior end but is not associated with a particular structure. Although it empties its contents through an opening in the cell membrane, this also does not appear to be a permanent pore. Paramecium has two contractile vacuoles, one at each end, which fill and contract alternately. They are permanent structures and the surplus water is conducted to the vacuoles by a series of
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Unformatted text preview: radiating channels. Other ciliates. There are many other species of ciliate. Vorticella has a stalk which can retract if the protozoan is disturbed. The cilia do not cover the body but are restricted to a double row on the upper margin. The cilia create a feeding current which wafts food particles into the oral groove. vacuole filling vacuole full and about to empty Photomicrograph of a stalked ciliate used in sewage treatment plants where they ingest bacteria. © A. Pasking © D.G. Mackean circle of cilia which create a water current, sweeping food particles into the oral groove oral groove nucleus contractile vacuole food vacuole contractile stalk pond weed Vorticella...
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