When Elodea leaves were placed in 10% NaCl, what was the result?
The cell membrane did not change at all because of the protection of the cell wall.
The cells burst because the solution was hypotonic.
The cell membrane shrank, but the central vacuole remained full.
The cell membrane shrank away from the cell wall because the solution was hypertonic.
The cell became turgid.
The Correct Answer is D
Choice A rationale: The cell membrane did not change at all because of the protection of the cell wall is incorrect because the cell wall does not prevent the movement of water across the cell membrane. The cell wall only provides mechanical support and prevents the cell from bursting in a hypotonic solution.
Choice B rationale: The cells burst because the solution was hypotonic is incorrect because the solution was hypertonic, not hypotonic. 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.
Choice C rationale: The cell membrane shrank, but the central vacuole remained full is incorrect because the central vacuole also loses water in a hypertonic solution. The central vacuole is a large organelle that stores water and other substances in the plant cell. When water leaves the cell, the central vacuole shrinks and the cell loses its turgor pressure.
Choice D rationale: The cell membrane shrank away from the cell wall because the solution was hypertonic is correct because this is what happens when a plant cell is placed in a hypertonic solution. The cell membrane and the cytoplasm contract and pull away from the cell wall, creating a gap between them. This is called plasmolysis and it can damage the cell.
Choice E rationale: The cell became turgid is incorrect because the cell becomes turgid in a hypotonic solution, not a hypertonic one. 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.
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 B
Explanation
Choice A rationale: Hypotonic is incorrect because hypotonic is a type of solution that has a higher concentration of water and lower concentration of solute than the cell placed in the solution. In a hypotonic solution, water moves into the cell and out of the solution by osmosis, causing the cell to swell.
Choice B rationale: Isotonic is correct because isotonic is a type of solution that has the same concentration of water and solute as the cell placed in the solution. In an isotonic solution, there is no net movement of water across the cell membrane.
Choice C rationale: Diffusive is incorrect because diffusive is an adjective that describes the movement of molecules from a region of high concentration to a region of low concentration, not a type of solution. Diffusion is the process by which molecules move across a membrane or a space due to their random motion.
Choice D rationale: Osmotic is incorrect because osmotic is an adjective that describes the movement of water across a semipermeable membrane, not a type of solution. Osmosis is the process by which water moves from a region of high water concentration to a region of low water concentration.
Choice E rationale: Hypertonic is incorrect because hypertonic is a type of solution that has a lower concentration of water and higher concentration of solute than the cell placed in the solution. In a hypertonic solution, water moves out of the cell and into the solution by osmosis, causing the cell to shrink.
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