BiologyBiologyChapter 3Chapter 3

3B-13B-1

Review QuestionsReview Questions

Why is homeostasis called an equilibrium? Why is homeostasis called an equilibrium? Why is homeostasis called dynamic?Why is homeostasis called dynamic?

It is an equilibrium because It involves a It is an equilibrium because It involves a balance between the cell an its environmentbalance between the cell an its environment

It is dynamic because once homeostasis is It is dynamic because once homeostasis is achieved, there is still movement of water achieved, there is still movement of water and solutes across the membraneand solutes across the membrane

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2. Compare and contrast optimal point, optimal 2. Compare and contrast optimal point, optimal range, range of tolerance, and limit of tolerancerange, range of tolerance, and limit of tolerance

Optimal point- the point where organisms function Optimal point- the point where organisms function bestbest

Optimal range- the limit within organism function Optimal range- the limit within organism function properlyproperly

Range of tolerance- an organism is stil alive, but Range of tolerance- an organism is stil alive, but begin to deterioratebegin to deteriorate

Limit of Tolerance- Organisms can no longer Limit of Tolerance- Organisms can no longer function properly-leading to deathfunction properly-leading to death

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3. Explain the difference between 3. Explain the difference between plasmolysis and cytolysisplasmolysis and cytolysis

Plasmolysis is the shrinking of cells due to Plasmolysis is the shrinking of cells due to water losswater loss

Cytolysis is the bursting of a cell due to Cytolysis is the bursting of a cell due to increased water pressureincreased water pressure

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4. Compare and contrast isotonic, hypotonic, and 4. Compare and contrast isotonic, hypotonic, and hypertonic solutionshypertonic solutions

They are each a comparison of two solutionsThey are each a comparison of two solutions If the concentration is equal the solutions are If the concentration is equal the solutions are

equal they are isotonicequal they are isotonic If they are not equal, the solution with the greater If they are not equal, the solution with the greater

concentration is hypertonic and the solution with concentration is hypertonic and the solution with the lesser concentration is hypotonicthe lesser concentration is hypotonic

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5. List two methods some cells use to withstand 5. List two methods some cells use to withstand hypotonic environments, discussing important hypotonic environments, discussing important structures and how they functionstructures and how they function

Plant cells may use a central vacuole that stores Plant cells may use a central vacuole that stores excess water- as it becomes full, it expands, excess water- as it becomes full, it expands, pushing the cytoplasmic contents against the cell pushing the cytoplasmic contents against the cell wall. This expansion increases pressure, it wall. This expansion increases pressure, it reaches a point where the pressure pushing water reaches a point where the pressure pushing water into the cell cannot overcome the pressure inside into the cell cannot overcome the pressure inside the cellthe cell

Question 5 ContinuedQuestion 5 Continued

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

Things to KnowThings to Know

The bursting of blood cells in hypotonic solution is The bursting of blood cells in hypotonic solution is called__________ (89)called__________ (89)

The solution in which the dissolved substances The solution in which the dissolved substances are the same concentration as they are in the are the same concentration as they are in the cell’s cytoplasm is a _______ solution. (89)cell’s cytoplasm is a _______ solution. (89)

A __________solution is exists when the A __________solution is exists when the substance dissolved outside the cells are more substance dissolved outside the cells are more abundant than those outside the cytoplasm (89)abundant than those outside the cytoplasm (89)

A solution that has a greater concetration of water A solution that has a greater concetration of water molecules than its cell it surrounds is a molecules than its cell it surrounds is a ________solution (89)________solution (89)