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 E
Explanation
Choice A rationale: The presence of chloroplasts is incorrect because chloroplasts are organelles that perform photosynthesis, not osmosis. Chloroplasts do not affect the water balance of the cell.
Choice B rationale: A plant cell will not burst in a hypotonic solution because water is moving out of the cell is incorrect because water moves into the cell in a hypotonic solution, not out of it. A hypotonic solution has a lower solute concentration than the cell, so water flows from the solution to the cell by osmosis.
Choice C rationale: Chloroplasts that help pump the excess water out of the cell is incorrect because chloroplasts do not have any role in pumping water out of the cell. The cell uses active transport to pump out excess water, which requires energy from ATP, not chloroplasts.
Choice D rationale: The plasma membrane is incorrect because the plasma membrane is permeable to water, so it cannot prevent water from entering the cell. The plasma membrane only regulates the passage of solutes, not water.
Choice E rationale: The cell wall is correct because the cell wall is a rigid structure that surrounds the plasma membrane and provides mechanical support to the cell. The cell wall can withstand the pressure of water entering the cell and prevent the cell from bursting. The cell wall is made of cellulose, a polysaccharide that is resistant to water.
Correct Answer is A
Explanation
Choice A rationale: A cover slip is correct because 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.
Choice B rationale: Clear paper is incorrect because clear paper is not suitable for covering a wet mount specimen. Clear paper is a type of paper that is transparent or translucent, but it is not thin or flat enough to fit over the specimen on the slide. Clear paper can also interfere with the passage of light or distort the image of the specimen.
Choice C rationale: Transparent tape is incorrect because transparent tape is also not suitable for covering a wet mount specimen. Transparent tape is a type of adhesive tape that is clear or see-through, but it is sticky and can damage the specimen or the slide. Transparent tape can also affect the quality of the image or the focus of the microscope.
Choice D rationale: Another glass slide is incorrect because another glass slide is too thick and heavy to cover a wet mount specimen. Another glass slide is a thin, flat piece of glass or plastic that can be used to place the specimen on, but not over it. Another glass slide can also crush the specimen or block the light source of the microscope.
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