After testing tonicity in the lab, the items that have been contaminated with blood can be disposed of in the trash can.

True or False?

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.

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.