What does the term motile mean?
Movable
Fixed
Magnification
Solid
The Correct Answer is A
Choice A rationale: Movable is correct because motile is an adjective that describes the ability of an organism or a cell to move by itself, using some form of locomotion, such as flagella, cilia, or pseudopodia. For example, some bacteria, protists, and sperm cells are motile.
Choice B rationale: Fixed is incorrect because fixed is the opposite of motile. Fixed is an adjective that describes the inability of an organism or a cell to move by itself, due to being attached to a substrate or a surface. For example, some plants, fungi, and coral are fixed.
Choice C rationale: Magnification is incorrect because magnification is not related to motility. Magnification is a measure of how much larger an image appears compared to the actual size of the object. Magnification is used in microscopy to observe small objects, such as cells.
Choice D rationale: Solid is incorrect because solid is not related to motility. Solid is a state of matter that has a definite shape and volume, due to the strong attraction between the molecules. Solid is contrasted with liquid and gas, which have no definite shape and can flow.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
Choice A reason: Biuret test is a test for the presence of proteins or peptides in a solution. It 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. ³
Choice B reason: Gram's iodine test is a test for the presence of starch in a solution. It 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. ⁴
Choice C reason: Ninhydrin test is a test for the presence of amines or amino acids in a solution. It involves adding ninhydrin reagent, which is a purple solution of ninhydrin, to the solution. If amines or amino acids are present, they react with ninhydrin to produce a purple color, often called Ruhemann's purple. ¹
Choice D 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 E 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. ⁵
Correct Answer is A
Explanation
Choice A rationale: Iodine is a chemical element that forms a brown solution of iodine and potassium iodide, known as iodine solution. When this solution is added to a sample that contains starch, it forms a complex with the starch molecules, which changes the color of the solution to blue-black. This is based on the fact that starch is a polysaccharide that has a helical structure, which can trap the iodine molecules inside. ²
Choice B rationale: Biuret is a chemical compound that forms a blue solution of copper (II) sulfate and sodium hydroxide, known as biuret reagent. When this reagent is added to a sample that contains proteins or peptides, it forms a complex with the copper (II) ions, which changes the color of the solution to violet or pink. This 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 C rationale: Benedict's is a chemical compound that forms a blue solution of copper (II) sulfate, sodium carbonate, and sodium citrate, known as Benedict's reagent. When this reagent is heated with a sample that contains reducing sugars, such as glucose or maltose, it reduces the copper (II) ions to copper (I) ions, which form a red, orange, or green precipitate of copper (I) oxide. This is based on the fact that reducing sugars have free aldehyde or ketone groups that can donate electrons to the copper (II) ions. ⁴
Choice D rationale: Phenol red is a chemical compound that forms a red solution that is used as a pH indicator. When this solution is added to a sample that has an acidic or neutral pH, it remains red or turns yellow. When this solution is added to a sample that has an alkaline pH, it turns pink or fuchsia. This is based on the fact that phenol red has a sulfonated hydroxyquinone group that can lose or gain protons depending on the pH of the solution. ⁵
Choice E rationale: Sudan IV is a chemical compound that forms a red powder that is used as a stain for lipids. When this powder is dissolved in a solvent and added to a sample that contains lipids, such as fats or oils, it dissolves in the lipids and stains them red. When this solution is added to a sample that does not contain lipids, it remains in the solvent and does not stain the sample. This is based on the fact that Sudan IV is a nonpolar compound that can dissolve in nonpolar substances like lipids, but not in polar substances like water. ⁶.
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