BIOD 171 Module 3 Exam Questions with 100% Correct Answers

A nanometer is defined as: Correct Answer 10 -9 or one-billionth of a meter True or False: A nanometer is longer than a micrometer Correct Answer False A nanometer is 1000x smaller than a micrometer Resolution and contrast are two critical factors that influence your ability to see an object. Explain each. Correct Answer Resolution refers to the distance between two objects at which the objects can still be seen as separate. Poor or low resolution means two or more objects may appear as one. Contrast on the other hand is the difference in light absorbance between two objects. Poor contrast gives a high background and makes the visualization of multiple objects difficult. For instance, trying to identify 2 dark colored objects at night (low light = low contrast) versus the same 2 objects in the middle of a sunny afternoon (bright light against 2 dark objects = high contrast). Assuming a fixed ocular, identify the part of the microscope you would adjust to enhance the magnification of a sample. Correct Answer Objective Only the oculars (eyepiece) and the objectives contribute to the magnification of the sample. Since the eyepiece is fixed, only the objectives could be altered. Assuming a constant (non-adjustable) light source power, identify the part of the microscope you would adjust to limit the amount of light entering the microscope. Correct Answer Iris diaphragm What is the total magnification on (relative to your eye) of a sample imaged with a 60x objective and a 10x eyepiece? Show your math. Correct Answer 60x objective x 10x ocular = 600x magnification True or False: Staining is often required to image a cell that is adherent and flat (thin). Correct Answer True Adherent, flat and unstained cells are almost invisible due to the limits on both resolution and contrast. Therefore, cell staining is often required to adequately image the sample.