Question

Why are contractile vacuoles useless in salt water?

Answer 1

Contractile vacuoles

1. The contractile vacuoles are a specialized type of vacuoles present in amoeba.
2. In salt water, the concentration of solutes outside the cell is higher than that inside, causing the water to flow out of the cell along the gradient of solute concentration.
3. Therefore, the expulsion of water does not require contractile vacuoles.
4. Since the solute concentration outside the cell in freshwater is lower than that within, osmosis causes water to enter the cell.
5. Contractile vacuoles are therefore needed to push the water outside against the concentration gradient.