Biology 11th Edition by Cecie Starr ,Ralph Taggart

Exercise 3

Water moves osmotically into Paramecium , a single-celled aquatic protist. If unchecked, the influx would bloat the cell and rupture its plasma membrane, and the cell would die. An energy-requiring mechanism that involves contractile vacuoles expels excess water. Water enters the vacuoles tubelike extensions and collects inside. A full vacuole contracts and squirts water out of the cell through a pore. Are Paramecium s surroundings hypotonic, hypertonic, or isotonic