Final answer:
Freshwater plant cells in saltwater lose water and may die due to a hypertonic environment, while a saltwater plant in freshwater may burst due to excess water intake. Fish adapt to their salinity environment and can suffer from osmotic pressure when placed in a non-native environment.
Step-by-step explanation:
When cells of a freshwater plant are placed in salt water, they are likely to lose water due to osmosis because the environment outside the plant cells is hypertonic (higher in solute concentration) compared to the inside of the cells. This results in the cells shrinking and potentially dying in a process known as plasmolysis. On the other hand, when a saltwater plant is placed in freshwater, the cells may take in too much water, causing them to swell and potentially burst in a process known as lysis.
Fish have evolved to cope with the salinity of their native environment. A freshwater fish placed in the ocean would lose too much water to its environment, whereas a saltwater fish placed in freshwater will take in too much water. Both scenarios are due to osmotic pressure, which is the movement of water across a semi-permeable membrane from an area of lower solute concentration to one of higher solute concentration.