Which objective lens provides the highest total magnification?

Choice A rationale: An isotonic solution has the same solute concentration as the plant cells, which means it has the same water potential. Water will move in and out of the plant cells at the same rate, causing them to remain unchanged in size and shape. This will not help the lettuce to become less wilted.

Choice B rationale: A hypertonic solution has a higher solute concentration than the plant cells, which means it has a lower water potential. Water will move out of the plant cells by osmosis, causing them to shrink and become plasmolysed. This will make the lettuce more wilted and not crisper.

Choice C rationale: Soaking the lettuce in water would have an effect, depending on the relative solute concentration of the water and the plant cells. Water will move across the cell membrane by osmosis, either into or out of the plant cells, causing them to change in size and shape.

Choice D rationale: A hypotonic solution has a lower solute concentration than the plant cells, which means it has a higher water potential. Water will move into the plant cells by osmosis, causing them to swell and become turgid. This will make the lettuce crisper and more appealing.

Choice E rationale: A hypotonic solution will cause the plant cells to gain water and become turgid, not more wilted. Wilted lettuce is caused by the loss of water from the plant cells, which makes them flaccid and soft.

Choice A rationale: High power is incorrect because high power is the second highest magnification objective lens, not the highest. High power is also called the 40x objective lens because it magnifies the specimen by 40 times. When combined with the 10x eyepiece lens, the total magnification is 400x.

Choice B rationale: Oil immersion is correct because oil immersion is the highest magnification objective lens. Oil immersion is also called the 100x objective lens because it magnifies the specimen by 100 times. When combined with the 10x eyepiece lens, the total magnification is 1000x. Oil immersion requires oil to be applied between the slide and the lens to reduce the refraction of light and increase the clarity of the image.

Choice C rationale: Low power is incorrect because low power is the second lowest magnification objective lens, not the highest. Low power is also called the 10x objective lens because it magnifies the specimen by 10 times. When combined with the 10x eyepiece lens, the total magnification is 100x.

Choice D rationale: Scanning is incorrect because scanning is the lowest magnification objective lens, not the highest. Scanning is also called the 4x objective lens because it magnifies the specimen by 4 times. When combined with the 10x eyepiece lens, the total magnification is 40x. Scanning is used to scan the whole slide and find the specimen.