Osmosis and Diffusion

Concept: Simple Diffusion

8m

Concept: Selective Permeability and Transport Proteins

5m

Concept: Electrochemical Grandients

6m

Concept: Osmosis

7m

Concept: Osmoregulation

11m

Problem: The movement solute of molecules along a concentration gradient from high to low is called:

1m

Problem: Osmosis requires a _______________ in order to occur.

1m

Problem: Two solutions of salt water are at different concentrations. The one with lower concentration is ____________________ to the one with higher concentration.

1m

Problem: When plant cells are _________ to their environment then the turgor pressure increases.

1m

Osmosis and Diffusion Additional Practice Problems

A cell whose cytoplasm has a concentration of 0.02 molar glucose is placed in a test tube of water containing 0.02 molar glucose. Assuming that glucose is not actively transported into the cell, which of the following terms describes the tonicity of the external solution relative to the cytoplasm of the cell? 

a. turgid 

b. hypertonic 

c. hypotonic 

d. flaccid 

e. isotonic

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Intravenous (IV) solutions administered to patients ae normally isotonic. Which of the following is most likely if an IV ofdistilled water is administered to a patient?

A. The cells that are exposed to hypotonic solutions will expand as water moves osmotically into the cells from the blood.

B. The cells that are exposed to hypotonic solutions will shrink as a result of salt moving out of the cells into the blood.

C. The cells that are exposed to hypertonic solutions will expand as a result of salt moving into the cells from the blood.

D. The cells that are exposed to hypertonic solutions will shrink as water moves out of the cells and into the blood.

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Which of the following is LEAST likely to play a role in the likelihood that a molecule will diffuse across the phospholipid bilayer of a cell's plasma membrane?

A. Concentration of the molecule on each side of the membrane.

B. Number of double bonds in the molecule

C. Polarity of the molecule

D. Size of the molecule

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If more sugar were added to the solution on the elft side of the tube, what would happen to the water level on the right side of the tube?

A. The water level would go down

B. The water level would rise

C. The water level would stay the same

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In the lab, you use a special balloon that is permeable to water but not sucrose to make an "artificial cell." The balloon is filled with a solution of 20% sucrose and 80% water and is immersed in a beaker containing a solution of 40% sucrose and 60% water. The solution in the balloon is ______ relative to the solution in the beaker.

A. hypertonic

B. hydrophilic

C. isotonic

D. hypotonic

E. hydrophobic

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What molecules are permeable to cell membrane? What molecule are impermeable to cell membrane? How do they cross plasma membrane?

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Suppose you dropped a potato strip into a solution. What could you have measured before and after to determine if osmosis occurred? 

Check all that apply.

A. color

B. mass

C. distance

D. volume (length x width x height)

E. number of sides

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The solute concentration in blood is equivalent to 0.9% NaCl.

Several drops of blood were added to three different solutions: 0.09% NaCl, 0.9% NaCl, and 9% NaCl. What would happen to the cells dipped in three different solutions?

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Describe the following types of transport processes in cells: simple diffusion, facilitated diffusion, active transport, pinocytosis, receptor-mediated endocytosis, phagocytosis, and exocytosis.


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If you were to do a 50% serial dilution, starting with a 10% concentration, how many dilutions would you have to make before getting 2.5% as your final concentration?

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Celery stalks that are immersed in fresh water for several hours become stiff and hard. Similar stalks left in a salt solution become limp and soft. From this we can deduce that the cells of the celery stalks are 

a. hypotonic to both fresh water and the salt solution. 

b. hypertonic to both fresh water and the salt solution. 

c. hypertonic to fresh water but hypotonic to the salt solution. 

d. hypotonic to fresh water but hypertonic to the salt solution. 

e. isotonic with fresh water but hypotonic to the salt solution. 


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List two properties that influence the rate of diffusion of a particle.

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Plants and animals that live in estuaries face a dilemma in maintaining water balance inside their cells. During high tide they are in salt water, while at low tide they are in fresh water.

At high tide a plant or animal cell will be in ____. 

a. An isotonic solution

b. A hypertonic solution

c. A hypotonic solution

d. Equilibrium

e. Osmosis

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If a cell has a 95% concentration of water in its cytoplasm and the environment surrounding the cell has a 90% concentration of water: 

a. Water will flow into the cell by osmosis

b. Water will flow out of the cell by active transport

c. Water will flow out of the cell by osmosis

d. Water will flow into the cell by active transport

e. Water will flow into the cell by facilitated diffusion

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If the environment surrounding a cell has a lower concentration of solute than the cell: 

a. The environment is isotonic to the cell

b. The environment is hypertonic to the cell

c. The cell will not experience a net gain or loss of water

d. The environment is hypotonic to the cell

e. The cell will die

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The diffusion of water across a selectively permeable (biological) membrane is: 

a. Facilitated diffusion

b. Active transport

c. A rare occurrence

d. Osmosis

e. Always beneficial to a cell

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Simple diffusion: 

a. Requires energy

b. Utilizes proteins to move molecules across a membrane

c. Moves molecules against a concentration gradient

d. Cannot occur without a membrane present

e. Does not require energy

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Osmosis can only occur if water travels through the

a. cell wall

b. semi-permeable membrane

c. vacuole

d. ER

e. cytoskeleton

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If two solutions have unequal concentrations of a solute, the solution with the lower concentration is called

a. isotonic

b. hypertonic

c. hypotonic

d. hypnotic

e. osmosis

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The movement of substances to regions of lower concentration is called

a. active transport

b. diffusion

c. osmosis

d. pumping

e. exocytosis

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If a cell has the same concentration of dissolved molecules as of its outside environment, the cell’s condition is called as being

a. isotonic

b. hypertonic

c. hypotonic

d. hydrophobic

e. hydrophilic

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Water passes quickly through cell membranes because:

a. the bilayer is hydrophilic.

b. it moves through hydrophobic channels.

c. water movement is tied to ATP hydrolysis.

d. it is a small, polar, charged molecule.

e. specialized proteins form hydrophilic channels.

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Protons are unable to cross the lipid bilayer because:

a. the lipid bilayer is too hydrophilic

b. protons are nonpolar

c. protons are too small

d. the lipid bilayer is only permeable to polar substances

e. none of the above

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If O2 is found in high concentration on the outside of a cell:

a. energy will be expended to pump it inside the cell.

b. it will passively diffuse out of the cell.

c. it will move inside the cell through a protein channel.

d. it will passively diffuse into the cell.

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