Biology Chapter 3 3B-1

Review Questions Why is homeostasis called an equilibrium? Why is homeostasis called dynamic? It is an equilibrium because It involves a balance between the cell an its environment It is dynamic because once homeostasis is achieved, there is still movement of water and solutes across the membrane

Review Questions 2. Compare and contrast optimal point, optimal range, range of tolerance, and limit of tolerance Optimal point- the point where organisms function best Optimal range- the limit within organism function properly Range of tolerance- an organism is stil alive, but begin to deteriorate Limit of Tolerance- Organisms can no longer function properly-leading to death

Review Questions 3. Explain the difference between plasmolysis and cytolysis Plasmolysis is the shrinking of cells due to water loss Cytolysis is the bursting of a cell due to increased water pressure

Review Questions 4. Compare and contrast isotonic, hypotonic, and hypertonic solutions They are each a comparison of two solutions If the concentration is equal the solutions are equal they are isotonic If they are not equal, the solution with the greater concentration is hypertonic and the solution with the lesser concentration is hypotonic

Review Questions 5. List two methods some cells use to withstand hypotonic environments, discussing important structures and how they function Plant cells may use a central vacuole that stores excess water- as it becomes full, it expands, pushing the cytoplasmic contents against the cell wall. This expansion increases pressure, it reaches a point where the pressure pushing water into the cell cannot overcome the pressure inside the cell

Question 5 Continued Some single celled organisms have a contractile vacuole used as a holding tank-once it becomes full it merges with the cell membrane and empties the water outside of the cell

Things to Know The bursting of blood cells in hypotonic solution is called__________ (89) The solution in which the dissolved substances are the same concentration as they are in the cell’s cytoplasm is a _______ solution. (89) A __________solution is exists when the substance dissolved outside the cells are more abundant than those outside the cytoplasm (89) A solution that has a greater concetration of water molecules than its cell it surrounds is a ________solution (89)