Osmosis

1. As a person becomes very dehydrated, the concentration of water in her blood decreases. In which direction will water move across the plasma membranes of her blood cells? What will happen to the volume of the cells as a consequence? Why is proper hydration important for multicellular organisms?

In dehydration, the cell volume would shrink as water moves from the inside of the cell to the outside of it to try to sustain homeostasis. The volume of the cells would shrink. Proper hydration is important for multicellular organisms as water is a basic need for cellular health. Water accounts for 60% of body weight, and the body needs water to regulate not only the circulatory system but also the pulmonary system.

2. Oops! You were cleaning out the aquariums in the biology lab and you accidentally placed the saltwater fish in the freshwater tank. What will happen to the cells of these fish?

If saltwater fish were placed into fresh water, the salt molecules in the fish would begin to absorb the water molecules from the fresh water. This would cause the fish to gain large amounts of water weight. The fresh water does not have enough salt concentration to satisfy the survival of the salt water fish. Therefore, the concentration of the cells would increase.

3. In some countries, human waste is used as a fertilizer. If produce is grown in this type of fertilizer, it is possible that it will be contaminated with the protozoan that causes amoebic dysentery. One method of removing the protist without ruining the food is to place the produce in a 5% salt solution. Explain how this would kill the protist. If you cleaned your lettuce this way, what would happen to the lettuce cells? How could you return them to normal?

Placing the protest in the salt solution would kill the protist due to the fact that protists have to make sure that they have enough water to maintain their structure and be able to move. The high salt solution would have a lower water...