Which of the following is most important when observing microorganisms through a microscope?

• A. Placing the slide upside down on the stage
• B. Focusing only with the coarse adjustment knob at high magnification
• C. Using the correct objective lens for desired magnification
• D. Leaving the condenser closed to reduce light

Answer: (C)

Verified step by step guidance

1. Understand the purpose of each microscope component mentioned: the slide placement, coarse adjustment knob, objective lens, and condenser.
2. Recognize that placing the slide upside down can affect the orientation of the specimen but is not generally critical for observation quality.
3. Know that focusing at high magnification should primarily be done with the fine adjustment knob, not the coarse adjustment knob, to avoid damaging the slide or lens.
4. Identify that the objective lens determines the magnification and resolution, so selecting the correct objective lens is crucial for observing microorganisms clearly.
5. Understand that the condenser controls the amount of light; leaving it closed reduces light and can hinder visibility, so it should be adjusted properly rather than left closed.