Question

1. when the egg was placed in the water, in which direction did the water molecules move (into or out of the cell), and how do you know? (2pts)
2. similar to an egg, the cells of a fish are likely to change as a result of salt concentration in the water. a freshwater (no salt) fish is placed in an aquarium with saltwater (a lot of salt). after a couple hours, the fish died. why? (think about how the water would move between the cells and the water in the aquarium) (2pts)

Explanation:

Step1: Understand osmosis principle

Osmosis is the movement of water molecules from an area of high water - potential (low solute concentration) to an area of low water - potential (high solute concentration) across a semi - permeable membrane.

Step2: Analyze egg in water

If the egg is placed in pure water, the water outside has a higher water potential compared to the inside of the egg (assuming the egg has solutes inside). So water molecules move into the cell. We know this because the egg may swell or gain weight if it is permeable to water.

Step3: Analyze fish in saltwater

A freshwater fish has cells with a lower salt concentration compared to the saltwater in the aquarium. Water will move out of the fish's cells (from high water potential inside the cells to low water potential in the saltwater) due to osmosis. This causes the cells to shrink and dehydrate the fish, eventually leading to its death.

Answer:

1. Water molecules move into the cell. We know this as the egg may swell if it is permeable to water, due to the higher water potential outside (in pure water) compared to inside the egg.
2. The fish died because water moved out of its cells into the salt - water aquarium. The saltwater has a lower water potential than the cells of the freshwater fish. This dehydration of the fish's cells led to its death.