Which mechanism directly counters water influx in freshwater protozoa?

💡 Explanation

When living in freshwater, protozoa encounter hypotonic conditions, osmosis drives continuous water influx; contractile vacuoles use active transport to expel excess water to maintain osmotic balance. Therefore vacuole excretion acts against influx, rather than permeability reduction, ion uptake, or mucus secretion impacting primary influx rates.

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