Some protozoans have special organelles called contractile vacuoles that continually eliminate excess water from the cell. The presence of these organelles, and the constant influx of water from the outside environment tells you that the environment

is hypotonic to the protozoans

Explanation:

The constant influx of water from the outside environment of the cell tells that the environment is hypotonic to the cell.

A hypotonic environment is one with a lower solute concentration than the cytosol. Hence, water osmotically moves from the environment into the cells of the protozoans. The water needs to constantly be removed from the cells, otherwise, they will become turgid and lyse away their contents.

mammal

explanation:

if the type of the food available changes, then the frequency of beak types will change, because birds with beaks more suited to the available food will be more successful over time.