AP BIOLOGY

THE CELL

STRUCTURE AND FUNCTION OF THE CELL

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Moves stage up and down for focusing; large amounts
A
Fine Focus Knob
B
Large Focus Knob
C
Coarse Adjustment Knob
D
Fine Adjustment Knob
Explanation: 

Detailed explanation-1: -Coarse Adjustment Knob-The coarse adjustment knob located on the arm of the microscope moves the stage up and down to bring the specimen into focus. The gearing mechanism of the adjustment produces a large vertical movement of the stage with only a partial revolution of the knob.

Detailed explanation-2: -COARSE ADJUSTMENT KNOB-A rapid control which allows for quick focusing by moving the objective lens or stage up and down. It is used for initial focusing.

Detailed explanation-3: -Rotate the coarse adjustment knob in a clockwise direction to bring the 10X objective closer to the slide. View through the eyepieces and, without disturbing the coarse adjustment setting, slowly rotate the fine adjustment knob until the specimen is in the sharpest possible focus.

Detailed explanation-4: -When focusing on high power while using a microscope, always use the fine adjustment knob to focus. This is because the working distance is extremely small and using the coarse adjustment knob risks cracking the glass slide or objective lens.

Detailed explanation-5: -Focusing knobs: located on both sides of the microscope. The larger, inner coarse adjustment knob moves the stage up and down much faster and farther than the smaller, outer fine adjustment knob. The coarse adjustment knob is used ONLY with the low power (4X, 10X) objectives.

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