BIO 201 UNCW - TEST 2| 200+ ACTUAL QUESTIONS
WITH CORRECT ANSWERS 2025
1. membrane mosaic structure ANS enables membrane function
2. phospholipid organization ANS organize spontaneously in aqueous solutions
tails form a hydrophobic barrier that will keep hydrophilic areas from going into the
center of the membrane
3. hydrophobic interactions ANS cage-like structure of water forms around the
hy- drophobe
hydrophobic exclusion
4. making a fluid membrane ANS 1. hydrophobic exclusion pushes the fatty acid
tails of phospholipids together
2. hydrogen bonds and hydration spheres form between water and the hydrophobic
heads
3. van der waals interactions among the hydrophobic portions of molecules deter-
mines the membrane fluidity
5. more van der waals forces ANS less fluidity
6. why is it important to maintain a constant body temperature? ANS to
maintain van der waals forces and membrane fluidity
7. cell membranes are semi fluid ANS non covalent bonds are made and broken
a lot molecules must be able to move in the membrane
https://www.stuvia.com/user/Mboffin
, 8. what makes the membrane fluid? ANS hydrophobic portions of membrane
mole- cules interact with each other by van der waals forces
9. cholesterol ANS only found in animals
can fill gaps between acyl chains (tails on the phospholipid) and create van der waals
forces
10. what happens if a membrane is less fluid? ANS you will not function as well
11. fevers ANS heat separates acyl chains and breaks van der waals forces
12. leaflet ANS describes one half (layer) of a phospholipid bilayer
13. types of movement in a leaflet ANS 1. lateral (side to side)
2. rotational (spin in a circle)
14. movement from one leaflet to another ANS called a flip flop
15. flippase ANS the protein enzyme required to flip flop
16. lipid structures ANS determines membrane fluidity
17. unsaturated carbon tails ANS enhance fluidity and resist solidification of the
mem- brane at colder temperatures
reduces van der waals forces
18. saturated carbon tails ANS sold at room temperature and liquid when
heated less fluidity, increase of van der waals forces
19. cholesterol embedded in the plasma membrane acts as a buffer ANS
stabilizes the membrane at higher temperatures and resists lower temperatures
https://www.stuvia.com/user/Mboffin
, 20. increased cholerstol = increased fluidity ANS increased van der waals
forces at high temps by filling holes made by fast moving phospholipids
decreased van der waals forces at low temps by breaking van der waals and pushing
slow moving phospholipids apart
21. 2 classes of proteins associate with cell membranes in 2 different ways AN
-
integral proteins and peripheral proteins
22. integral proteins ANS have one or more regions embedded in or
transversing through the membrane
7 hydrophobic alpha helices = 7TMD
23. peripheral proteins ANS stick to other proteins
do not integrate in hydrophobic plasma membrane
24. main functions of proteins associated with the cell membrane ANS 1.
transport of molecules across the plasma membrane
2. enzymatic activity
3. signal transduction (ex ANS salmonella makes a signaling molecule and more
actin cytoskeleton brings it in)
4. cell-cell recognition (ex ANS blood type)
5. intercellular junctions
6. attachment of the cell to the cytoskeleton or extracellular matrix
25. unity ANS all organisms have shared cell features
26. diversity ANS individual species have some unique features
https://www.stuvia.com/user/Mboffin
WITH CORRECT ANSWERS 2025
1. membrane mosaic structure ANS enables membrane function
2. phospholipid organization ANS organize spontaneously in aqueous solutions
tails form a hydrophobic barrier that will keep hydrophilic areas from going into the
center of the membrane
3. hydrophobic interactions ANS cage-like structure of water forms around the
hy- drophobe
hydrophobic exclusion
4. making a fluid membrane ANS 1. hydrophobic exclusion pushes the fatty acid
tails of phospholipids together
2. hydrogen bonds and hydration spheres form between water and the hydrophobic
heads
3. van der waals interactions among the hydrophobic portions of molecules deter-
mines the membrane fluidity
5. more van der waals forces ANS less fluidity
6. why is it important to maintain a constant body temperature? ANS to
maintain van der waals forces and membrane fluidity
7. cell membranes are semi fluid ANS non covalent bonds are made and broken
a lot molecules must be able to move in the membrane
https://www.stuvia.com/user/Mboffin
, 8. what makes the membrane fluid? ANS hydrophobic portions of membrane
mole- cules interact with each other by van der waals forces
9. cholesterol ANS only found in animals
can fill gaps between acyl chains (tails on the phospholipid) and create van der waals
forces
10. what happens if a membrane is less fluid? ANS you will not function as well
11. fevers ANS heat separates acyl chains and breaks van der waals forces
12. leaflet ANS describes one half (layer) of a phospholipid bilayer
13. types of movement in a leaflet ANS 1. lateral (side to side)
2. rotational (spin in a circle)
14. movement from one leaflet to another ANS called a flip flop
15. flippase ANS the protein enzyme required to flip flop
16. lipid structures ANS determines membrane fluidity
17. unsaturated carbon tails ANS enhance fluidity and resist solidification of the
mem- brane at colder temperatures
reduces van der waals forces
18. saturated carbon tails ANS sold at room temperature and liquid when
heated less fluidity, increase of van der waals forces
19. cholesterol embedded in the plasma membrane acts as a buffer ANS
stabilizes the membrane at higher temperatures and resists lower temperatures
https://www.stuvia.com/user/Mboffin
, 20. increased cholerstol = increased fluidity ANS increased van der waals
forces at high temps by filling holes made by fast moving phospholipids
decreased van der waals forces at low temps by breaking van der waals and pushing
slow moving phospholipids apart
21. 2 classes of proteins associate with cell membranes in 2 different ways AN
-
integral proteins and peripheral proteins
22. integral proteins ANS have one or more regions embedded in or
transversing through the membrane
7 hydrophobic alpha helices = 7TMD
23. peripheral proteins ANS stick to other proteins
do not integrate in hydrophobic plasma membrane
24. main functions of proteins associated with the cell membrane ANS 1.
transport of molecules across the plasma membrane
2. enzymatic activity
3. signal transduction (ex ANS salmonella makes a signaling molecule and more
actin cytoskeleton brings it in)
4. cell-cell recognition (ex ANS blood type)
5. intercellular junctions
6. attachment of the cell to the cytoskeleton or extracellular matrix
25. unity ANS all organisms have shared cell features
26. diversity ANS individual species have some unique features
https://www.stuvia.com/user/Mboffin
