Lesson 2 osmosis and diffusion in the marine environment

The document summarizes how different fish species regulate water concentration in their cells when in environments with different salt concentrations. Some fish, like those in marine environments, actively transport ions to maintain higher internal salt concentrations than the surrounding water to prevent their cells from bursting. Other fish, called osmoconformers, allow their internal salt concentrations to rise and fall passively with the environment. Maintaining precise internal regulation requires energy, so some species like cod produce high concentrations of urea to control balances. The document emphasizes the importance of these mechanisms for fish to adapt to varying salinity conditions in their habitats.