Which variables affect the rate of diffusion? (Select all that apply.)
Density of media
Size of molecules
Concentration gradient
Membrane permeability
pH
Correct Answer : A,B,C,D,E
Choice A rationale: Density of media affects the rate of diffusion because it influences the frequency of collisions between the diffusing molecules and the molecules of the medium. The denser the medium, the slower the diffusion rate, and vice versa.
Choice B rationale: Size of molecules affects the rate of diffusion because it determines how easily the molecules can move through the spaces between the molecules of the medium. The smaller the molecules, the faster the diffusion rate, and vice versa.
Choice C rationale: Concentration gradient affects the rate of diffusion because it is the difference in concentration of the diffusing molecules between two regions. The higher the concentration gradient, the faster the diffusion rate, and vice versa.
Choice D rationale: Membrane permeability affects the rate of diffusion because it is the ability of the membrane to allow the diffusing molecules to pass through it. The more permeable the membrane, the faster the diffusion rate, and vice versa.
Choice E rationale: pH affects the rate of diffusion because it is the measure of acidity or alkalinity of the medium. pH can affect the charge and shape of the diffusing molecules, which can affect their ability to cross the membrane or interact with the molecules of the medium. pH can also affect the membrane permeability by altering the charge and shape of the membrane proteins.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is {"dropdown-group-1":"B","dropdown-group-2":"B"}
Explanation
Choice A rationale: Low, high is incorrect because it is the opposite of the direction of simple diffusion. Simple diffusion is the passive movement of molecules along their concentration gradient, which means from high to low concentration.
Choice B rationale: Low, equal is incorrect because it is not the final state of simple diffusion. Simple diffusion will continue until the concentration of molecules is equal on both sides of the membrane.
Choice C rationale: Equal, low is incorrect because it is not possible for simple diffusion. Simple diffusion will stop when the concentration of molecules is equal on both sides of the membrane, and there will be no net movement of molecules.
Choice D rationale: Equal, high is incorrect because it is not possible for simple diffusion. Simple diffusion will stop when the concentration of molecules is equal on both sides of the membrane, and there will be no net movement of molecules.
Choice E rationale: High, low is correct because it is the definition of simple diffusion. Simple diffusion is the passive movement of molecules along their concentration gradient, which means from high to low concentration.
Correct Answer is A
Explanation
Choice A reason: Benedict's test is a test for the presence of reducing sugars, such as glucose or maltose, in a solution. The test involves adding Benedict's reagent, which is a blue solution of copper (II) sulfate, sodium carbonate, and sodium citrate, to the solution and heating it in a water bath. If reducing sugars are present, they reduce the copper (II) ions to copper (I) ions, which form a red, orange, or green precipitate of copper (I) oxide. The color and amount of the precipitate indicate the concentration of reducing sugars in the solution. ¹
Choice B reason: Brown paper test is a test for the presence of lipids, such as fats or oils, in a solution. The test involves placing a drop of the solution on a piece of brown paper and letting it dry. If lipids are present, they leave a translucent spot on the paper, which can be seen by holding the paper against a light source. The test is based on the fact that lipids are nonpolar and do not dissolve in water, but can dissolve in organic solvents and stain the paper. ²
Choice C reason: Biuret test is a test for the presence of proteins or peptides in a solution. The test involves adding Biuret reagent, which is a blue solution of copper (II) sulfate and sodium hydroxide, to the solution. If proteins or peptides are present, they form a complex with the copper (II) ions, which changes the color of the solution to violet or pink. The test is based on the fact that proteins and peptides have peptide bonds, which have nitrogen atoms that can coordinate with the copper (II) ions. ³
Choice D reason: Iodine test is a test for the presence of starch in a solution. The test involves adding iodine solution, which is a brown solution of iodine and potassium iodide, to the solution. If starch is present, it forms a complex with the iodine molecules, which changes the color of the solution to blue-black. The test is based on the fact that starch is a polysaccharide that has a helical structure, which can trap the iodine molecules inside. ⁴
Choice E reason: Wendelspecht test is a fictional test that does not exist in reality. It is a made-up name that has no meaning or relevance to the topic of this question. Therefore, it cannot be a valid answer.
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