BIO 141: CHAPTER 4: BIOLOGY OF THE CELL: TEST
QUESTIONS WITH COMPLETE SOLUTIONS
What are four characteristics of membrane proteins? -- Answer ✔✔ 1. compose half of
plasma membrane by weight
2. can "float" and move about fluid bilayer
3. most of a membrane's functions determined by resident proteins
4. classified as integral or peripheral proteins
What are six functional categories of proteins? -- Answer ✔✔ 1. transport proteins
(channels, carriers, and pumps)
2. cell surface receptors (neurotransmitters and hormone receptors)
3. identity markers (immune system cells distinguishing healthy cells from foreign cells)
4. enzymes
5. anchoring sites (secure cytoskeleton to plasma membrane)
6. cell-adhesion proteins (perform cell to cell attachments)
What type of plasma membrane protein provides the means for moving materials across
the plasma membrane -- Answer ✔✔ transport proteins
,What are three subtypes of transport proteins? -- Answer ✔✔ channels, carriers,
pumps, symporters, and antiporters
What is the passive process of membrane transport? -- Answer ✔✔ does not require
energy and depends on substances moving down the concentration gradient
What is the active process of membrane transport? -- Answer ✔✔ requires energy
- movement of a substance up its concentration gradient (active transport)
- release of a membrane-bound vesicle (vesicular transport)
What is diffusion? -- Answer ✔✔ moves from area of greater concentration to area of
lesser concentration. If unopposed, continues until substance reaches equilibrium
The rate that substances diffuse is dependent on what two things? -- Answer ✔✔ 1. The
steepness of its concentration gradient (a measure of the difference in concentration of
a substance between two areas. A steeper concentration gradient causes a faster rate of
diffusion)
2. Temperature. Higher temperature leads to a faster rate of diffusion
What is simple cellular diffusion (4 things)? -- Answer ✔✔ 1. molecules passing between
phospholipid molecules
2. solutes small and nonpolar
3. include respiratory gases (O2 and CO2), some fatty acids, ethanol, urea
4. cannot be regulated by plasma membrane
What are three characteristics of facilitated diffusion -- Answer ✔✔ 1. transport
process for small charged or polar solutes
2. require assistance from plasma membrane proteins
3. maximum rate of transport determined by number of channels and carriers
,Is the phospholipid bilayer polar or nonpolar? -- Answer ✔✔ nonpolar
What are two types of facilitated diffusion -- Answer ✔✔ channel-meditated and
carrier-meditated
What are four characteristics of channel-meditated diffusion? -- Answer ✔✔ 1.
movement of small ions through water-filled protein channels
2. channels specific for one ion type
3. leak channels are continuously open
4. gated channels are usually closed and open in response to stimulus
What are seven characteristics of carrier meditated diffusion? -- Answer ✔✔ 1. small,
polar molecules assisted across membrane by carrier protein
2. transport substances such as glucose
3. binding of substance cause change in carrier protein shape
4. releases substances on other side of membrane
5. move substances down their gradient
6. carrier transporting only one substance termed a uniporter
7. very similar to channels
A carrier protein that transports only one substance is called a _________ -- Answer
✔✔ uniporter (ex. glucose carriers)
How does O2 diffuse into a cell and CO2 diffuse out of a cell? -- Answer ✔✔ Through
simple diffusion, passing between phospholipid molecules in the plasma membrane
What is osmosis? -- Answer ✔✔ 1. passive movement of water through selectively
permeable membrane (usually preventing passage of most solutes)
2. occurs in response to differences in water concentration on either side of the
membrane
, What are two ways water crosses the membrane? -- Answer ✔✔ 1. slip between
molecules of phospholipid bilayer
2. moves through integral protein water channels (aquaporins)
A solution with a greater concentration of solutes contains a (higher/lower)
concentration of water -- Answer ✔✔ lower
What is osmotic pressure? -- Answer ✔✔ pressure exerted by movement of water
across semipermeable membrane
What is hydrostatic pressure? -- Answer ✔✔ the pressure exerted by a fluid on the
inside wall of its container
What is tonicity? -- Answer ✔✔ ability of a solution to change the volume or pressure
of the cell by osmosis
What is an isotonic solution? -- Answer ✔✔ 1. both cytosol and solution with same
relative concentration of solutes
2. no net movement of water
An example of a solution that is isotonic to erythrocytes is normal saline with a
concentration of _________ NaCl -- Answer ✔✔ 0.9%
What is a hypotonic solution (relative to cytosol) -- Answer ✔✔ 1. solution with a
lower concentration of solutes than cytosol
2. water moving down concentration gradient
3. may cause cell lysis(rupture)
QUESTIONS WITH COMPLETE SOLUTIONS
What are four characteristics of membrane proteins? -- Answer ✔✔ 1. compose half of
plasma membrane by weight
2. can "float" and move about fluid bilayer
3. most of a membrane's functions determined by resident proteins
4. classified as integral or peripheral proteins
What are six functional categories of proteins? -- Answer ✔✔ 1. transport proteins
(channels, carriers, and pumps)
2. cell surface receptors (neurotransmitters and hormone receptors)
3. identity markers (immune system cells distinguishing healthy cells from foreign cells)
4. enzymes
5. anchoring sites (secure cytoskeleton to plasma membrane)
6. cell-adhesion proteins (perform cell to cell attachments)
What type of plasma membrane protein provides the means for moving materials across
the plasma membrane -- Answer ✔✔ transport proteins
,What are three subtypes of transport proteins? -- Answer ✔✔ channels, carriers,
pumps, symporters, and antiporters
What is the passive process of membrane transport? -- Answer ✔✔ does not require
energy and depends on substances moving down the concentration gradient
What is the active process of membrane transport? -- Answer ✔✔ requires energy
- movement of a substance up its concentration gradient (active transport)
- release of a membrane-bound vesicle (vesicular transport)
What is diffusion? -- Answer ✔✔ moves from area of greater concentration to area of
lesser concentration. If unopposed, continues until substance reaches equilibrium
The rate that substances diffuse is dependent on what two things? -- Answer ✔✔ 1. The
steepness of its concentration gradient (a measure of the difference in concentration of
a substance between two areas. A steeper concentration gradient causes a faster rate of
diffusion)
2. Temperature. Higher temperature leads to a faster rate of diffusion
What is simple cellular diffusion (4 things)? -- Answer ✔✔ 1. molecules passing between
phospholipid molecules
2. solutes small and nonpolar
3. include respiratory gases (O2 and CO2), some fatty acids, ethanol, urea
4. cannot be regulated by plasma membrane
What are three characteristics of facilitated diffusion -- Answer ✔✔ 1. transport
process for small charged or polar solutes
2. require assistance from plasma membrane proteins
3. maximum rate of transport determined by number of channels and carriers
,Is the phospholipid bilayer polar or nonpolar? -- Answer ✔✔ nonpolar
What are two types of facilitated diffusion -- Answer ✔✔ channel-meditated and
carrier-meditated
What are four characteristics of channel-meditated diffusion? -- Answer ✔✔ 1.
movement of small ions through water-filled protein channels
2. channels specific for one ion type
3. leak channels are continuously open
4. gated channels are usually closed and open in response to stimulus
What are seven characteristics of carrier meditated diffusion? -- Answer ✔✔ 1. small,
polar molecules assisted across membrane by carrier protein
2. transport substances such as glucose
3. binding of substance cause change in carrier protein shape
4. releases substances on other side of membrane
5. move substances down their gradient
6. carrier transporting only one substance termed a uniporter
7. very similar to channels
A carrier protein that transports only one substance is called a _________ -- Answer
✔✔ uniporter (ex. glucose carriers)
How does O2 diffuse into a cell and CO2 diffuse out of a cell? -- Answer ✔✔ Through
simple diffusion, passing between phospholipid molecules in the plasma membrane
What is osmosis? -- Answer ✔✔ 1. passive movement of water through selectively
permeable membrane (usually preventing passage of most solutes)
2. occurs in response to differences in water concentration on either side of the
membrane
, What are two ways water crosses the membrane? -- Answer ✔✔ 1. slip between
molecules of phospholipid bilayer
2. moves through integral protein water channels (aquaporins)
A solution with a greater concentration of solutes contains a (higher/lower)
concentration of water -- Answer ✔✔ lower
What is osmotic pressure? -- Answer ✔✔ pressure exerted by movement of water
across semipermeable membrane
What is hydrostatic pressure? -- Answer ✔✔ the pressure exerted by a fluid on the
inside wall of its container
What is tonicity? -- Answer ✔✔ ability of a solution to change the volume or pressure
of the cell by osmosis
What is an isotonic solution? -- Answer ✔✔ 1. both cytosol and solution with same
relative concentration of solutes
2. no net movement of water
An example of a solution that is isotonic to erythrocytes is normal saline with a
concentration of _________ NaCl -- Answer ✔✔ 0.9%
What is a hypotonic solution (relative to cytosol) -- Answer ✔✔ 1. solution with a
lower concentration of solutes than cytosol
2. water moving down concentration gradient
3. may cause cell lysis(rupture)
