The positive control for the iodine test was the
Distilled water
Olive oil
Albumin solution
Starch solution
The Correct Answer is D
Choice A rationale: Distilled water is not a positive control, but a negative control for the iodine test. Distilled water is a pure solvent that does not contain any starch or other carbohydrates. It does not react with the iodine solution and does not produce any color change. A negative control is used to confirm that there is no response to the reagent or the microorganism used in the test. It is used to set the baseline and verify that the detecting reagent is working properly³.
Choice B rationale: Olive oil is not a positive control, but a negative control for the iodine test. Olive oil is a lipid that does not contain any starch or other carbohydrates. It does not react with the iodine solution and does not produce any color change. A negative control is used to confirm that there is no response to the reagent or the microorganism used in the test. It is used to set the baseline and verify that the detecting reagent is working properly³.
Choice C rationale: Albumin solution is not a positive control, but a negative control for the iodine test. Albumin is a protein that does not contain any starch or other carbohydrates. It does not react with the iodine solution and does not produce any color change. A negative control is used to confirm that there is no response to the reagent or the microorganism used in the test. It is used to set the baseline and verify that the detecting reagent is working properly³.
Choice D rationale: Starch solution is a positive control for the iodine test. Starch is a polysaccharide that contains many glucose units linked by glycosidic bonds. Starch reacts with the iodine solution and produces a blue-black color. A positive control is used to confirm that the test works and gives a positive result when the substance is present³.
Choice E rationale: Glucose solution is not a positive control, but a negative control for the iodine test. Glucose is a monosaccharide that does not contain any glycosidic bonds. Glucose does not react with the iodine solution and does not produce any color change. A negative control is used to confirm that there is no response to the reagent or the microorganism used in the test. It is used to set the baseline and verify that the detecting reagent is working properly³.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is D
Explanation
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.
Correct Answer is ["A","B","E","F"]
Explanation
Choice A rationale: Transfer pipette is correct because you need a transfer pipette to transfer a drop of water or a liquid specimen onto the center of the slide. A transfer pipette is a plastic or glass tube with a bulb at one end that can suck up and release liquids.
Choice B rationale: Clean slide is correct because you need a clean slide to place the specimen on. A slide is a thin, flat piece of glass or plastic that can be viewed under a microscope. A clean slide ensures that there is no contamination or interference from other substances.
Choice C rationale: Bunsen burner is incorrect because you do not need a Bunsen burner to make a wet mount. A Bunsen burner is a device that produces a flame by mixing gas and air. A Bunsen burner is used for heating, sterilizing, or burning substances, not for making a wet mount.
Choice D rationale: Timer is incorrect because you do not need a timer to make a wet mount. A timer is a device that measures or indicates the passage of time. A timer is used for timing experiments, not for making a wet mount.
Choice E rationale: Tweezers is correct because you need tweezers to pick up and place the specimen on the slide. Tweezers are a pair of metal or plastic pincers that can grasp and hold small objects. Tweezers are useful for handling delicate or microscopic specimens.
Choice F rationale: Cover slip is correct because you need a cover slip to cover the specimen on the slide. A cover slip is a thin, transparent piece of glass or plastic that can be placed over the specimen on the slide. A cover slip protects the specimen from drying out, dust, or damage, and creates a flat surface for viewing under the microscope.
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