BIO 253 EXAM 1 QUESTIONS AND ANSWERS
(A+ SOLUTION GUIDE)
1. Which statement accurately reflects excitation-contraction coupling in car- diac cells?
a) Na+ from the depolarization directly causes the opening of Ryanodine receptors
b) Ryanodine receptors are open during the Depolarization phase of the action potential
c) Contraction is directly tied to the opening of T-type Ca channels
d) Contraction is directly tied to the opening of L-type Ca channels
e) Contraction is directly tied to the stimulation of DHP proteins linked to the Ryanodine receptors: Contraction
is directly tied to the opening of L-type Ca channels
2. How does the resting membrane potential depend on the NA/K ATPase pump?: the RMP is dependent on
the typical gradients of Na and K, which is established by the Na/K ATPase pump
3. How does the secondary active transporter depend on the activity of the Na/K ATPase pump?: It uses the Na
gradient created by the NA/K ATPase pump (primary active transport)
4. The Na/K ATPase pump determines intracellular and extracellular
concentrations, which in turn affect " active transporters": Na, secondary
5. How does the difference of ions inside vs outside the cell arise?: From primary active transporters that move
Na, K, and Ca
6. What are the 3 components needed for transcellular transport?: a primary active transporter (Na/K ATPase
pump), a secondary active transporter, and a facilitated diffusion transporter
7. The substances that can cross an epithelium via paracellular transport vary by epithelium, why?: The ability for
substances to move by paracellular transport depends on how dense the tight junctions are that join adjacent cells.
8. Osmotically active particles that are a quantity/unit of dissolved particles: -
osmole
9. The force produced by osmosis, equivalent to the equal and opposite force necessary to prevent osmosis by the
application of an external pressure: os- motic pressure
, 10. How is the osmolarity of extracellular and intracellular fluids affected by a positive salt balance?: Increased
osmolarity of extracellular (1st) then intracellular fluids
11. How is the volume of extracellular and intracellular fluids affected by a pos- itive salt balance?: Extracellular
volume= increaseIntracellular volume= decrease
12. How is the osmolarity of extracellular and intracellular fluids affected by a negative salt balance?: Osmolarity
of extracellular fluids= decreased (1st)Osmo- larity of intracellular fluids= decreased
13. How is the volume of extracellular and intracellular fluids affected by a neg- ative salt balance?: Intracellular
volume= increaseExtracellular volume= decrease
14. How is the osmolarity of extracellular and intracellular fluids affected by a positive water balance?:
Osmolarity of extracellular fluids= decreased (1st)Os- molarity of intracellular fluids= decreased
15. How is the volume of extracellular and intracellular fluids affected by a positive water balance?: Extracellular
volume= increases (due to excess water)In- tracellular volume= increases
16. How is the osmolarity of extracellular and intracellular fluids affected by a negative water balance?: Osmolarity
of extracellular fluids= increased (1st)Osmo- larity of intracellular fluids= increased
17. How is the volume of extracellular and intracellular fluids affected by a negative water balance?:
Extracellular volume= decreases (due to water loss)In- tracellular volume= decreases
18. Do salt or water imbalances affect the intracellular or extracellular fluid first?: extracellular fluid, wate
rmoves into/out of the intracellular compartment to "match" the osmolarity, which changes the volume of the intracellular
compartment
19. Is a surplus of NaCl in the extracellular fluid a + salt balance, - salt balance,
+ water balance, or - water balance: Positive salt balance
20. Is less than normal amounts of NaCl in the extracellular fluid a + salt balance, - salt balance, + water
balance, or - water balance: negative salt balance
21. Is a surplus of water in the extracellular fluid a + salt balance, - salt balance,
+ water balance, or - water balance: positive water balance
22. Is a less than normal amount of water in the extracellular fluid a + salt balance, - salt balance, + water
balance, or - water balance: negative water balance
23. The membrane potential at which a permeable ion will reach equilibrium, in consideration of its electrical and
chemical driving forces: equilibrium potential
24. If the potential of a membrane is -70mV and K permeability is increased, will K move toward -90mV
quickly or slowly?: slowly, (-70)-(-90)= 20 mV
25. If the potential of a membrane is +50mV and K permeability is increased, will K move toward -90mV
quickly or slowly?: Quickly, (50)-(-90)= 140mV
26. What types of molecules can pass unchecked by the cell membrane?: non polar molecules, some uncharged polar
molecules, ions (with channels)
27. What factors influence the rate of diffusion through membranes?: The difference in concentration of the
molecule, surface area of the membrane, and the permeability of the membrane to the molecule
28. Are charged particles (ions) that diffuse through channels subject to the same rules as those particles that
pass through the lipid bilayer? What addi- tional factor influences their movement?: Yes, the diffusion rate is still
influenced by concentration difference, surface area, and permeability. Ions are also influenced by the charge (potential) of
the membrane
29. What factors determine the amount of Na/K pumped by the Na/K ATPase pump?: Availability of ATP and
the concentration gradients of Na and of K
(A+ SOLUTION GUIDE)
1. Which statement accurately reflects excitation-contraction coupling in car- diac cells?
a) Na+ from the depolarization directly causes the opening of Ryanodine receptors
b) Ryanodine receptors are open during the Depolarization phase of the action potential
c) Contraction is directly tied to the opening of T-type Ca channels
d) Contraction is directly tied to the opening of L-type Ca channels
e) Contraction is directly tied to the stimulation of DHP proteins linked to the Ryanodine receptors: Contraction
is directly tied to the opening of L-type Ca channels
2. How does the resting membrane potential depend on the NA/K ATPase pump?: the RMP is dependent on
the typical gradients of Na and K, which is established by the Na/K ATPase pump
3. How does the secondary active transporter depend on the activity of the Na/K ATPase pump?: It uses the Na
gradient created by the NA/K ATPase pump (primary active transport)
4. The Na/K ATPase pump determines intracellular and extracellular
concentrations, which in turn affect " active transporters": Na, secondary
5. How does the difference of ions inside vs outside the cell arise?: From primary active transporters that move
Na, K, and Ca
6. What are the 3 components needed for transcellular transport?: a primary active transporter (Na/K ATPase
pump), a secondary active transporter, and a facilitated diffusion transporter
7. The substances that can cross an epithelium via paracellular transport vary by epithelium, why?: The ability for
substances to move by paracellular transport depends on how dense the tight junctions are that join adjacent cells.
8. Osmotically active particles that are a quantity/unit of dissolved particles: -
osmole
9. The force produced by osmosis, equivalent to the equal and opposite force necessary to prevent osmosis by the
application of an external pressure: os- motic pressure
, 10. How is the osmolarity of extracellular and intracellular fluids affected by a positive salt balance?: Increased
osmolarity of extracellular (1st) then intracellular fluids
11. How is the volume of extracellular and intracellular fluids affected by a pos- itive salt balance?: Extracellular
volume= increaseIntracellular volume= decrease
12. How is the osmolarity of extracellular and intracellular fluids affected by a negative salt balance?: Osmolarity
of extracellular fluids= decreased (1st)Osmo- larity of intracellular fluids= decreased
13. How is the volume of extracellular and intracellular fluids affected by a neg- ative salt balance?: Intracellular
volume= increaseExtracellular volume= decrease
14. How is the osmolarity of extracellular and intracellular fluids affected by a positive water balance?:
Osmolarity of extracellular fluids= decreased (1st)Os- molarity of intracellular fluids= decreased
15. How is the volume of extracellular and intracellular fluids affected by a positive water balance?: Extracellular
volume= increases (due to excess water)In- tracellular volume= increases
16. How is the osmolarity of extracellular and intracellular fluids affected by a negative water balance?: Osmolarity
of extracellular fluids= increased (1st)Osmo- larity of intracellular fluids= increased
17. How is the volume of extracellular and intracellular fluids affected by a negative water balance?:
Extracellular volume= decreases (due to water loss)In- tracellular volume= decreases
18. Do salt or water imbalances affect the intracellular or extracellular fluid first?: extracellular fluid, wate
rmoves into/out of the intracellular compartment to "match" the osmolarity, which changes the volume of the intracellular
compartment
19. Is a surplus of NaCl in the extracellular fluid a + salt balance, - salt balance,
+ water balance, or - water balance: Positive salt balance
20. Is less than normal amounts of NaCl in the extracellular fluid a + salt balance, - salt balance, + water
balance, or - water balance: negative salt balance
21. Is a surplus of water in the extracellular fluid a + salt balance, - salt balance,
+ water balance, or - water balance: positive water balance
22. Is a less than normal amount of water in the extracellular fluid a + salt balance, - salt balance, + water
balance, or - water balance: negative water balance
23. The membrane potential at which a permeable ion will reach equilibrium, in consideration of its electrical and
chemical driving forces: equilibrium potential
24. If the potential of a membrane is -70mV and K permeability is increased, will K move toward -90mV
quickly or slowly?: slowly, (-70)-(-90)= 20 mV
25. If the potential of a membrane is +50mV and K permeability is increased, will K move toward -90mV
quickly or slowly?: Quickly, (50)-(-90)= 140mV
26. What types of molecules can pass unchecked by the cell membrane?: non polar molecules, some uncharged polar
molecules, ions (with channels)
27. What factors influence the rate of diffusion through membranes?: The difference in concentration of the
molecule, surface area of the membrane, and the permeability of the membrane to the molecule
28. Are charged particles (ions) that diffuse through channels subject to the same rules as those particles that
pass through the lipid bilayer? What addi- tional factor influences their movement?: Yes, the diffusion rate is still
influenced by concentration difference, surface area, and permeability. Ions are also influenced by the charge (potential) of
the membrane
29. What factors determine the amount of Na/K pumped by the Na/K ATPase pump?: Availability of ATP and
the concentration gradients of Na and of K
