What does the term motile mean?

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

Choice A rationale: 4x is incorrect because 4x is the lowest magnification objective lens that does not require oil to be applied. 4x is also called the scanning objective lens because it is used to scan the whole slide and find the specimen. 4x has a large field of view and a low resolution.

Choice B rationale: 10x is incorrect because 10x is the medium magnification objective lens that does not require oil to be applied. 10x is also called the low power objective lens because it is used to observe the specimen in more detail. 10x has a smaller field of view and a higher resolution than 4x.

Choice C rationale: 40x is incorrect because 40x is the high magnification objective lens that does not require oil to be applied. 40x is also called the high power objective lens because it is used to observe the specimen in greater detail. 40x has a smaller field of view and a higher resolution than 10x.

Choice D rationale: 100x is correct because 100x is the highest magnification objective lens that requires oil to be applied. 100x is also called the oil immersion objective lens because it is used to observe the specimen in the highest detail. 100x has a very small field of view and a very high resolution. Oil is applied between the slide and the lens to reduce the refraction of light and increase the clarity of the image.