Solute Q moves across the plasma membrane via protein channels - VCE - SSCE Biology - Question 21 - 2010 - Paper 1
Question 21
Solute Q moves across the plasma membrane via protein channels. Solute R moves across the plasma membrane by simple diffusion. The rate of movement of each solute in... show full transcript
Worked Solution & Example Answer:Solute Q moves across the plasma membrane via protein channels - VCE - SSCE Biology - Question 21 - 2010 - Paper 1
Step 1
A. solute Q is lipid soluble.
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Answer
This statement is unlikely to be true since solute Q moves via protein channels, indicating that it is not lipid soluble. Lipid-soluble substances can typically diffuse directly through the membrane, bypassing the need for protein channels.
Step 2
B. solute Q saturates the protein channels.
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This is a reasonable conclusion. The graph showing the rate of movement of solute Q suggests that it reaches a maximum rate, indicating that the protein channels are saturated at higher concentrations of solute Q.
Step 3
C. the gradient of the graph for solute R will increase as the temperature decreases.
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This statement is incorrect. Generally, an increase in temperature increases the kinetic energy of molecules, leading to a higher rate of diffusion. Therefore, as temperature decreases, the rate of movement for solute R would likely decrease, not increase.
Step 4
D. as solute R is metabolised within a cell, its rate of movement across the membrane decreases.
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This statement is plausible if solute R is being used up or transformed within the cell. As the concentration of solute R decreases inside the cell due to metabolism, the driving force for diffusion might decrease as well, resulting in a lower rate of movement across the membrane.
