7. Which pair of factors is inversely proportional to the rate of diffusion? A. Concentration gradient and surface area over which diffusion occurs. B. Distance over which diffusion occurs and size of diffusion molecule. C. Size of diffusion molecule and concentration gradient. D. Surface area over which diffusion occurs and distance over which diffusion occurs.

7. Which pair of factors is inversely proportional to the rate of diffusion? A. Concentration gradient and surface area over which diffusion occurs. B. Distance over which diffusion occurs and size of diffusion molecule. C. Size of diffusion molecule and concentration gradient. D. Surface area over which diffusion occurs and distance over which diffusion occurs.

Human Physiology: From Cells to Systems (MindTap Course List)

9th Edition

ISBN:9781285866932

Author:Lauralee Sherwood

Publisher:Lauralee Sherwood

Chapter3: The Plasma Membrane And Membrane Potential

Section: Chapter Questions

Problem 2SQE: One of the important uses of the Nernst equation is in describing the flow of ions across plasma...

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One of the important uses of the Nernst equation is in describing the flow of ions across plasma membranes. Ions move under the influence of two forces: the concentration gradient (given in electrical units by the Nernst equation) and the electrical gradient (given by the membrane voltage). This is summarized by Ohms law: Ix=Gx(VmEx) which describes the movement of ion x across the membrane. I is the current in amperes (A); G is the conductance, a measure of the permeability of x, in Siemens (S), which is I/V;Vm is the membrane voltage; and Ex is the equilibrium potential of ion x. Not only does this equation tell how large the current is, but it also tells what direction the current is flowing. By convention, a negative value of the current represents either a positive ion entering the cell or a negative ion leaving the cell. The opposite is true of a positive value of the current. a. Using the following information, calculate the magnitude of Na [ Na+ ]0=145mM,[ Na+ ]i=15mM,Gna+=1nS,Vm=70mV b. Is Na+ entering or leaving the cell? c. Is Na+ moving with or against the concentration gradient? Is it moving with or against the electrical gradient?
1. Qualitative thinking: For diffusion, it is important to understand the differences between diffusion rate and diffusive flux. a. Define diffusive flux and diffusion rate and write their equations based on Fick's first law. b. Write an equation that relates the two and show how the units balance on each side. c. Fill in the what happens to diffusive flux and diffusion rate (increases, decreases or stays the same) when the variables in the left column changes as noted: Variable Concentration difference, AC Diffusion distance, Ax Diffusion area, A Diffusion coefficient, D Change Increases Increases Increases Increases Diffusive flux Diffusion rate
If you made a hematocrit in two tubes. Tube A is made of 0.60M NaCl, and Tube B is made of 1.00M of NaCl, describe how the cell would respond in these solutions? Which would have a higher rate of osmosis? If the cell is permeable to NaCl, which would have a higher rate of diffusion?
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The average time it takes for a molecule to diffuse adistance of x cm is given byt = x2/2D where t is the time in seconds and D is the diffusioncoefficient. Given that the diffusion coefficient ofglucose is 5.7 × 10−7cm2/s, calculate the time it wouldtake for a glucose molecule to diffuse 10 μm, which isroughly the size of a cell.