BIOD 171 MODULE 3 EXAM Questions With 100% Verified Answers Guaranteed Success.

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. True or False: A cell that is adherent, flat (thin), and unstained is easily identified using bright field microscopy - correct answer False: Adherent, flat cells are almost invisible due to the limits on both resolution and contrast Which of the following could be seen clearly by the unaided eye? Select all that apply. A. Bacteria with diameter of 24 μm B. Protozoa with diameter of 150 μm C. Virus with a diameter of 0.2 μm D. Skin cell with diameter of 1500 μm - correct answer B. Protozoa with diameter of 150 μm D. Skin cell with diameter of 1500 μm The unaided eye can, on average, clearly resolve objects > 100 μm 2. Which of the following could NOT be seen clearly by the unaided eye? Select all that apply. A. Bacteria with diameter of 24 μm B. Protozoa with diameter of 150 μm C. Virus with a diameter of 0.2 μm D. Skin cell with diameter of 1500 μm - correct answer A. Bacteria with diameter of 24 μm C. Virus with a diameter of 0.2 μm The unaided eye can, on average, clearly resolve objects > 100 μm 1. Label the following unmarked microscope components (numbered arrows) by matching it with the components provided (letters). - correct answer 1F- eyepiece 2D- neck 3B- fine adjustment knob 4G- objective 5A- stage 6H- base This type of microscope is best suited for visualizing GFP, RFP, and YFP proteins. - correct answer Fluorescence This type of microscope utilizes ultraviolet (UV) light to illuminate stained objects. - correct answer Fluorescence This type of microscope uses a specialized condenser and objective to amplify the slight differences between cells and background. - correct answer Phase-contrast This type of microscope enhances contrast between specimen and background but does not permit the visualization of intracellular structures. - correct answer Dark Field This type of microscope uses neither halogen nor UV light sources but rather lasers to illuminate stained cells in high resolution. - correct answer Confocal This type of microscope is capable of capturing images in multiple focal planes, rendering a specimen in 3-D - correct answer Confocal Identify what type of electron microscope was used to capture the following image and explain your choice. (picture labeled B) - correct answer The image was captured using a Scanning Electron Microscope (SEM). The above image shows the trademark 'shell' image (no subcellular organelles are visible) reminiscent of SEM. Only TEM is capable of visualizing subcellular substrucutres. Identify what type of electron microscope was used to capture the following image and explain your choice. (picture labeled A) - correct answer The above image is captured via a Transmission Electron Microscope (TEM). Even at 20nm resolution (inset image), subcellular substructures are still visible. The image lacks the outside 'shell' only appearance of SEM. Gram-Positive cells appear [answer1] in color due to a [answer2] peptidoglycan layer in the cell wall. - correct answer 1. Purple 2. Thick Gram-Negative cells appear [answer1] in color due to a [answer2] peptidoglycan layer in the cell wall. - correct answer 1. Pink 2. Thin True or False: A Giemsa stain can be used to determine the presence of pathogenic bacteria. - correct answer True Pathogenic bacteria would appear pink while non-pathogenic bacteria would appear purple. True or False: The distinguishing characteristic of Gram-Negative bacteria is the presence of LPS in the outer membrane. - correct answer True True or False: Following the decolorization step of the Gram stain, Gram-Negative bacteria will appear colorless. - correct answer True True or False: If you wish to study the motiity of an organism you cannot heat fix, but you can chemically fix the specimen - correct answer False Both heat and chemical fixation strategies will kill the cell, making motility observation impossible Name one substance capable of chemically fixing cells to a slide. - correct answer Any of the following are true: Paraformaldehyde, ethanol or methanol. You suspect a patient may have TB. Once a sample has been obtained, it is sent off to the lab for an acid-fast stain. If the patient were infected with TB, describe what you would expect to see on the stained slide. - correct answer I would expect to see red cells (TB+) on a blue background (TB negative). You want to observe the size and shape of a cell. What is the easiest staining technique that you could perform? Name at least one dye you would use during this process. - correct answer Simple stainining and crystal violet could be used. True or False: If a patient is suspected of having malaria, a Giemsa stain would be an appropriate differential test to perform. - correct answer True Giesma stains are often used in the clinical setting aid in the diagnosis of blood parasites.