When testing tonicity in Elodea cells, once Elodea cells were placed in distilled water, what did you observe? Select all that apply.
Cell membranes pressed tightly against the cell walls.
Many of the cells had burst.
Full central vacuoles.
Many of the cells had become crenated.
Correct Answer : A,C
Choice A rationale: Cell membranes pressed tightly against the cell walls is correct because this is what happens when a plant cell is placed in a hypotonic solution. A hypotonic solution has a higher concentration of water than the cell, so water moves into the cell and out of the solution by osmosis, causing the cell to swell and press against the cell wall. This is called turgor and it helps the cell maintain its shape and rigidity.
Choice B rationale: Many of the cells had burst is incorrect because plant cells do not burst in a hypotonic solution, unlike animal cells. Plant cells have a rigid cell wall that prevents them from bursting, even when they are full of water. The cell wall can withstand the pressure of water entering the cell.
Choice C rationale: Full central vacuoles is correct because this is also what happens when a plant cell is placed in a hypotonic solution. The central vacuole is a large organelle that stores water and other substances in the plant cell. When water enters the cell, the central vacuole expands and fills up the cell, increasing its turgor pressure.
Choice D rationale: Many of the cells had become crenated is incorrect because crenation is the opposite of what happens in a hypotonic solution. Crenation is the process by which a cell shrinks and becomes wrinkled due to water loss in a hypertonic solution. A hypertonic solution has a lower concentration of water than the cell, so water moves out of the cell and into the solution by osmosis, causing the cell to shrink.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is E
Explanation
Choice A rationale: Microwaves are a type of electromagnetic radiation with low energy and long wavelengths. They are not absorbed by plants for photosynthesis, but rather pass through them or are reflected by them¹.
Choice B rationale: Infrared is a type of electromagnetic radiation with low energy and long wavelengths. It is not absorbed by plants for photosynthesis, but rather heats up the plant tissues or is reflected by them².
Choice C rationale: Gamma rays are a type of electromagnetic radiation with high energy and short wavelengths. They are not absorbed by plants for photosynthesis, but rather damage the plant cells or are blocked by the atmosphere³.
Choice D rationale: Ultraviolet is a type of electromagnetic radiation with high energy and short wavelengths. It is not absorbed by plants for photosynthesis, but rather harms the plant pigments or is filtered by the ozone layer⁴.
Choice E rationale: Visible light is a type of electromagnetic radiation with moderate energy and wavelengths. It is the only form of electromagnetic radiation that is absorbed by plants for photosynthesis, specifically by the pigments such as chlorophyll and carotenoids in the photosystems⁵. Visible light consists of a spectrum of colors, ranging from violet to red, and plants use different colors for different aspects of photosynthesis⁶.
Correct Answer is C
Explanation
Choice A rationale: Sudan IV is not a reagent for protein detection, but a reagent for lipid detection. Sudan IV is a red dye that binds to non-polar molecules, such as fats and oils. Sudan IV stains lipids red, while leaving water-soluble molecules, such as proteins, unstained¹.
Choice B rationale: Benedict's is not a reagent for protein detection, but a reagent for sugar detection. Benedict's is a blue solution that contains copper sulfate, sodium carbonate, and sodium citrate. Benedict's reacts with reducing sugars, such as glucose and fructose, and reduces the copper ions from blue to orange-red².
Choice C rationale: Biuret is a reagent for protein detection. Biuret is a blue solution that contains copper sulfate and sodium hydroxide. Biuret reacts with peptide bonds, which are the bonds that link amino acids in proteins. Biuret changes color from blue to violet when it binds to protein molecules³.
Choice D rationale: Iodine is not a reagent for protein detection, but a reagent for starch detection. Iodine is a brown solution that forms a complex with starch, a polysaccharide composed of glucose units. Iodine changes color from brown to blue-black when it interacts with starch molecules⁴.
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