1. The cell membrane (also known as the plasma membrane) surrounding every cell is composed primarily of ______.

A.DNAB.ProteinC. CarbohydratesD.Phospholipids

DNA

Protein

Carbohydrat

es

Phospholip

ids

25% 25%25%25%

2. The phospholipids in the cell membrane are arranged in a bilayer (double layer). How are the phospholipid molecules arranged in this bilayer?

A.The nonpolar (hydrophobic) ends of the molecules faces inwards

B. The polar (hydrophilic) ends of the molecules faces inwards

C. The fatty acid tails of the molecules faces inward

D.Both A and CE. Both B and C

The nonpolar (hyd

rophob...

The polar (hydro

philic) e

...

The fatty acid

tails

of th...

Both A and C

Both B and C

20% 20% 20%20%20%

Channels through the phospholipid membrane are formed by

A. ProteinsB. DNAC. CelluloseD. Cholesterol

ProteinsDNA

Cellulose

Cholesterol

25% 25%25%25%

3. The term permeability means

A.The ability of a substance to bend B. The ability of a substance to allow

gases or liquids to pass throughC. The ability of a substance to

dissolveD.The ability of a substance to exist

for a long time with out deteriorating.

The ability of a

substa

nce...

The ability of a

substa

nce...

The ability of a

substa

nce...

The abilit

y of a

substa

nc...

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4. In diffusion, molecules move from _________________ concentration in a process that __________________ additional energy.

A.high to low; requiresB.high to low: does

NOT requireC.low to high; requiresD.low to high; does

NOT require

high to

low; re

quires

high to

low: d

oes NOT re

...

low to high; re

quires

low to high; d

oes NOT r..

.

25% 25%25%25%

Additional energy is not required, because diffusion occurs due to the random motion of the molecules.

5. A hypotonic solution is one that a

A. contains a higher concentration of solute particles

B. contains an equal concentration of solute particles

C. contains a lower concentration of solute particles.

D. is at a higher temperatureE. is at a lower temperature

20% 20% 20%20%20%

The prefix hypo means below or under. (To remember this, think of the word hypothermia which is when one’s body temperature drops below the normal body temperature.)

If the solute (such as salt or sugar) concentration outside is lower than that inside the cell, then the outside environment is hypotonic.

The prefix hyper means above or over.

If the solute (such as salt or sugar) concentration outside is higher than that inside the cell, then the outside environment is hypertonic.

6. If a cell with a 0.2 M sucrose concentration inside is placed in a solution that has a 0.1 M sucrose concentration, the process of osmosis will occur. In this case,

A.sucrose will move into the cellB.sucrose will move out of the cellC. the cell will expand due to water gainD.the cell will shrink due to water lossE. both A and CF. both B and D

sucro

se will

move into th

...

sucro

se will

move out of ..

.

the cell w

ill exp

and due ..

the cell w

ill sh

rink d

ue t...

both A and C

both B and D

17% 17% 17%17%17%17%

Sucrose is disaccharide that is too large to move through the selectively permeable cell membrane. (Osmosis occurring means that it is the water moving through the membrane)

Hints to understanding the direction of movement of water in osmosis:

Remember that in passive transport (diffusion and osmosis) molecules always move from high concentrations to low concentration.

However, solution concentrations are given in terms of the solute, but in osmosis it the water that moves through the membrane.

To avoid getting confused by this, you can remember that if it has a higher solute concentration it will have a lower concentration of water. Examples:

3% sucrose solution is 97% water8% sucrose solution is 92% water 3 %sucrose

(97% water)

8% salt (92% water)

7. If a cell with a 0.8% salt concentration inside is placed in a 0.9% salt solution,

A. the cell will shrink due to water loss

B. salt will move out of the cell

C. the cell will expand due to water gain

D. salt will move out of the cellE. both A and DF. both B and C

the ce

ll will

shrin

k due t...

salt

will move

out of th

e...

the ce

ll will

expand due...

salt w

ill move out o

f the ...

both A and D

both B and C

17% 17% 17%17%17%17%

Salt is an ionic compound that can not move through the nonpolar barrier of the phospholipid membrane (without specialized channels).

In osmosis, water will move in the direction of the higher SOLUTE concentration. Thus hypertonic solutions, such as one high in salt, causes cells to lose water. • Drinking salt water will dehydrate our cells• Plants will wilt in a hypertonic solution.

8. Which kind(s) of solution outside of a cell could cause it to swell and potentially lyse (burst open)?

A. a hypertonic solutionB. a hypotonic solutionC. an isotonic solutionD. both A and CE. both B and C

a hyperto

nic so

lution

a hypotonic s

olution

an isotonic

solution

both A an

d C

both B and C

20% 20% 20%20%20%

9. In an isotonic solution

A. the cell swellsB. the cell shrinksC. there is NO movement

of water in or out of the cell

D. there is no NET movement of water

the ce

ll swells

the ce

ll shrin

ks

there is

NO move

ment o...

there is

no NET

move

me..

25% 25%25%25%

Water is constantly moving and diffusing through a cell membrane. In an isotonic solution, the movement of water into the cell is equal to the movement of water out of the cell. There is a DYNAMIC EQUILIBRIUM.

10. When a substance is secreted from a cell in a process in which a vesicle fuses with the plasma membrane to released to the outside, it is called

A. endocytosisB. exocytosisC. osmosisD. halitosis

Endocytosis

Exocyt

osis

osmosis

halito

sis

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11. O2 is a small, nonpolar molecule and it is present outside the cell in high concentration. It can enterthe cell by

A. Diffusion through the membrane

B. Passive transportC. Active transportD. A and BE. A and C

Diffusion th

rough th

e ...

Passive tr

ansp

ort

Active

transp

ort

A and B

A and C

20% 20% 20%20%20%

12. Glucose is a larger polar molecule. If it is present outside of the cell in high concentration, it can enter the cell by

A. Facilitated diffusion through specialized channels

B. Passive transportC. Active transportD. A and BE. A and C

Facil

itated diffusio

n thr..

.

Passive tr

ansp

ort

Active

transp

ort

A and B

A and C

20% 20% 20%20%20%

13. An amino acid (a large polar molecule) is present outside the cell in low concentration. It can be brought into the cell by

A. Facilitated diffusion through specialized channels

B. Passive transportC. Active transportD. A and BE. A and C Fa

cilita

ted diffusion th

r...

Passive tr

ansp

ort

Active

transp

ort

A and B

A and C

20% 20% 20%20%20%

1. D2. D3. B4. B5. C6. C7. A8. B9. D10. B

11.D12.D13.C