Question 1

If the gradient of the flux is negative, it means that

Accepted Answer

A)   The concentration at the point where the gradient is negative must be increasing with time.
B)   The concentration is at steady state.
C)   The flux is positive.
D)   The concentration at any point is decreasing with distance.
E)   The concentration is constant.F) A) and B)
G) A) and E)

Question 2

The major reason that the apparent diffusion coefficient of Ca2+ in muscle cell cytosol is much lower than in water is that

Accepted Answer

A)   The cytosol is more viscous than water
B)   The re are obstacles to the free movement of Ca2+ in the cytosol that aren't present in water
C)   Cytosol contains fixed proteins that bind Ca2+, slowing its movement
D)   The cytosol moves most electrolytes, but not Ca2+, around by convection
E)   Ca2+ causes solidification or gelling of the cytosolF) All of the above
G) B) and C) C

Question 3

According to the Stokes-Einstein equation, if the radius of one particle is twice the radius of a second particle ( r1 = 2 r2)  , then the relative value of their diffusion coefficients should be

Accepted Answer

A)   D 1 = 2 D2
B)   D 1 = D2 / 2
C)   D 2 = D2 / 4
D)   D 1 = D2 / 8
E)   D 1 = D2 / 16F) A) and B)
G) None of the above

Question 4

The diffusion coefficient of Na+, K+ and many more solutes is slower in cytosol than in water because

Accepted Answer

A)   The cytosol is more viscous than water
B)   There are obstacles to the free movement of ions in the cytosol that aren’t present in water
C)   Cytosol contains fixed proteins that bind ions, slowing their movem ent
D)   The cytosol moves most electrolytes around by convection
E)   Ca2+ causes solidification or gelling of the cytosolF) C) and E)
G) None of the above

Question 5

Diffusion of a small non-electrolyte (D = 0.5 x 10-5 cm2s-1)  across a 50 µm cell takes about

Accepted Answer

A)   2.5 milliseconds
B)   25 milliseconds
C)   2.5 seconds
D)   25 seconds
E)   250 secondsF) B) and D)
G) B) and C)

Question 6

Fick’s second law of diffusion follows from the first law if you apply

Accepted Answer

A)   The continuity equation
B)   Poiseuille’s equation
C)   LaPlace’s Law
D)   The conservation of mom entum
E)   The random walkF) D) and E)
G) B) and D) A

Question 7

The Stokes -Einstein equation is valid only if the diffusing particles are

Accepted Answer

A)   At equilibrium (there is no concentration gradient) 
B)   Warm
C)   Cold
D)   Spheres
E)   NewtonianF) B) and C)
G) B) and E)

Question 8

Which of the following are appropriate units for a diffusion coefficient?

Accepted Answer

A)   cm s-1
B)   Joules s-1
C)   N s-1
D)   cm 2 s-1
E)   cm 3 s-1F) A) and B)
G) A) and E) D

Question 9

Consider two spherical cells that are identical in all respects except that cell one has a radius that is 20% greater than the radius of cell 2 (r1 = 1.2 r2) . One substance is transported into the cell passively. The relative flow of the material across the membranes of the two cells is given as

Accepted Answer

A)   Q 1 = 1.2 Q 2
B)   Q 1 = 1.44 Q 2
C)   Q 1 = Q2
D)   Q 1 = 1.728 Q 2
E)   Cannot be determined from the information givenF) A) and C)
G) A) and B)

Question 10

If Ca > Cb and a > b, where a and b are x-coordinates, then

Accepted Answer

A)   The gradient of C is negative and diffusive flux is positive, going from a to b
B)   The gradient of C is positive and diffusive flux is negative, going from a to b
C)   The gradient of C is negative and diffusive flux is negative, going from b to a
D)   The gradient of C is positive and diffusive flux is negative, going from a to b.
E)   The gradient of C is negative and diffusive flux is positive, going from b to a.F) C) and D)
G) A) and D)

Question 11

Consider two spherical cells that are identical in all respects except that cell one has a radius that is 20% greater than the radius of cell 2 (r1 = 1.2 r2) . One substance is transported into the cell pass ively. The relative flux of the material across the membranes of the two cells is given as

Accepted Answer

A)   J1 = 1.2 J2
B)   J1 = 1.44 J2
C)   J1 = J2
D)   J1 = 1.728 J2
E)   Cannot be determined from the information given.F) A) and B)
G) C) and E)

Question 12

In the random walk derivation of Fick’s Second Law, the diffusion coefficient was equated to

Accepted Answer

A)    λ2/2tc \lambda^{2} / 2 t_{c} λ2/2tc​ 
B)   kt / β\betaβ 
C)    λ\lambdaλ  / tc
D)    λ2 \lambda^{2}λ2  / <v> 
E)   tc /  λ\lambdaλF) B) and E)
G) None of the above

Exam 4: Diffusion

If the gradient of the flux is negative, it means that

Correct Answer
verified

The major reason that the apparent diffusion coefficient of Ca²⁺ in muscle cell cytosol is much lower than in water is that

Correct Answer
verified
C

According to the Stokes-Einstein equation, if the radius of one particle is twice the radius of a second particle ( r₁ = 2 r₂) , then the relative value of their diffusion coefficients should be

Correct Answer
verified

The diffusion coefficient of Na⁺, K⁺ and many more solutes is slower in cytosol than in water because

Correct Answer
verified

Diffusion of a small non-electrolyte (D = 0.5 x 10^-5 cm²s^-1) across a 50 µm cell takes about

Correct Answer
verified

Fick’s second law of diffusion follows from the first law if you apply

Correct Answer
verified
A

The Stokes -Einstein equation is valid only if the diffusing particles are

Correct Answer
verified

Which of the following are appropriate units for a diffusion coefficient?

Correct Answer
verified
D

Consider two spherical cells that are identical in all respects except that cell one has a radius that is 20% greater than the radius of cell 2 (r1 = 1.2 r2) . One substance is transported into the cell passively. The relative flow of the material across the membranes of the two cells is given as

Correct Answer
verified

If C_a > C_b and a > b, where a and b are x-coordinates, then

Correct Answer
verified

Consider two spherical cells that are identical in all respects except that cell one has a radius that is 20% greater than the radius of cell 2 (r1 = 1.2 r2) . One substance is transported into the cell pass ively. The relative flux of the material across the membranes of the two cells is given as

Correct Answer
verified

In the random walk derivation of Fick’s Second Law, the diffusion coefficient was equated to

Correct Answer
verified

Exam 4: Diffusion

If the gradient of the flux is negative, it means that

Correct AnswerverifiedShow Answer

The major reason that the apparent diffusion coefficient of Ca2+ in muscle cell cytosol is much lower than in water is that

Correct AnswerverifiedC

According to the Stokes-Einstein equation, if the radius of one particle is twice the radius of a second particle ( r1 = 2 r2) , then the relative value of their diffusion coefficients should be

Correct AnswerverifiedShow Answer

The diffusion coefficient of Na+, K+ and many more solutes is slower in cytosol than in water because

Correct AnswerverifiedShow Answer

Diffusion of a small non-electrolyte (D = 0.5 x 10-5 cm2s-1) across a 50 µm cell takes about

Correct AnswerverifiedShow Answer

Fick’s second law of diffusion follows from the first law if you apply

Correct AnswerverifiedA

The Stokes -Einstein equation is valid only if the diffusing particles are

Correct AnswerverifiedShow Answer

Which of the following are appropriate units for a diffusion coefficient?

Correct AnswerverifiedD

Consider two spherical cells that are identical in all respects except that cell one has a radius that is 20% greater than the radius of cell 2 (r1 = 1.2 r2) . One substance is transported into the cell passively. The relative flow of the material across the membranes of the two cells is given as

Correct AnswerverifiedShow Answer

If Ca > Cb and a > b, where a and b are x-coordinates, then

Correct AnswerverifiedShow Answer

Consider two spherical cells that are identical in all respects except that cell one has a radius that is 20% greater than the radius of cell 2 (r1 = 1.2 r2) . One substance is transported into the cell pass ively. The relative flux of the material across the membranes of the two cells is given as

Correct AnswerverifiedShow Answer

In the random walk derivation of Fick’s Second Law, the diffusion coefficient was equated to

Correct AnswerverifiedShow Answer

Correct Answer
verified

The major reason that the apparent diffusion coefficient of Ca²⁺ in muscle cell cytosol is much lower than in water is that

Correct Answer
verified
C

According to the Stokes-Einstein equation, if the radius of one particle is twice the radius of a second particle ( r₁ = 2 r₂) , then the relative value of their diffusion coefficients should be

Correct Answer
verified

The diffusion coefficient of Na⁺, K⁺ and many more solutes is slower in cytosol than in water because

Correct Answer
verified

Diffusion of a small non-electrolyte (D = 0.5 x 10^-5 cm²s^-1) across a 50 µm cell takes about

Correct Answer
verified

Correct Answer
verified
A

Correct Answer
verified

Correct Answer
verified
D

Correct Answer
verified

If C_a > C_b and a > b, where a and b are x-coordinates, then

Correct Answer
verified

Correct Answer
verified

Correct Answer
verified