Transcript Biology 3B-1 - secondary

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 tankonce 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)