A group of single cell organisms collected from the ocean was brought into the lab for examination. The lab assistant was concerned that the water had become full of toxic waste products and so added clean water to the culture. All of the organisms died, and when she looked at them under the microscope, all she could see were bits and pieces of them scattered throughout the water. What likely happened?

She added the water which was hypotonic to the organism so they ruptured.

Explanation:

As the single-cell organism was isolated from the ocean so they must be adapted to live in a hypertonic environment because the ocean water is salty water. So when this organism is put in clean water than due to change in salt concentration the water for the cell became hypotonic which means the solute concentration outside the organism became low.

Water moves from low solute concentration to high solute concentration therefore in this condition water will move from outside to inside the organism which results in swelling and rupturing of those organisms.