M3_ Module 3 Review_ Essential Microbiology with Lab-2021

Ques 0 / 0 pts tion 1 Your Answer: Define the measurements micrometer and nanometer. micrometer is 10^-6 m nanometer is 10^-9 m A micrometer (µm) is defined as being one-millionth of a meter and is commonly designated at 10 meters. A nanometer (nm) equals 10 m or one-billionth of a meter. -6 -9 Ques 0 / 0 pts tion 2 What are the two critical factors that influence your ability to see an object? This study source was downloaded by from CourseH on :11:38 GMT -05:00 4/29/23, 8:38 PM M3: Module 3 Review: Essential Microbiology with Lab-2021-Stepp Your Answer: resolution contrast Resolution and contrast. Resolution refers to the distance between two objects at which the objects still can be seen as separate. Poor or low resolution means two (or more) objects may appear as one. The contrast 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). Ques 0 / 0 pts tion 3 Your Answer: If you wish to increase the amount of light going into a microscope, what part would you adjust? diaphragm The iris diaphragm controls the amount of light that passes through the sample and into the objective lens. Thus, as you open the iris more light is permitted to pass through to illuminate the sample. Ques 0 / 0 pts tion 4 This study source was downloaded by from CourseH on :11:38 GMT -05:00 4/29/23, 8:38 PM M3: Module 3 Review: Essential Microbiology with Lab-2021-Stepp Your Answer: As light passes through a microscope, what is the last piece that light passes before reaching your eyes? ocular lens/eye piece Once light passes through the sample and the objective lens it is directed through the ocular lens, or eyepiece, directly into your eye. Ques 0 / 0 pts tion 5 Your Answer: How is the total magnification of an object calculated? ocular magnification x objective lens magnification =total magnification Total magnification is calculated by multiplying the power of the objective and the power of the eyepiece. For instance, a 40x objective with a 10x eyepiece would make an object appear (40 x 10) 400 times larger (400x). Ques 0 / 0 pts tion 6 Your Answer: What is one limitation of fixing your sample? you cannot see motility any more because the organism is dead This study source was downloaded by from CourseH on :11:38 GMT -05:00 4/29/23, 8:38 PM M3: Module 3 Review: Essential Microbiology with Lab-2021-Stepp Fixation requires you to irreversibly kill your sample. Thus, determining the motility (cell movement) of a sample is impossible. Fixation also runs the risk of distorting the specimen shape and arrangement. Ques 0 / 0 pts tion 7 Your Answer: Phase-contrast microscopy provided what benefits to imaging? help you visualize certain structures that would otherwise be invisible, so you can see live cells without staining Phase contrast microscope can provide detailed images of live cells without staining. By using specialized condensers and objectives, a phase contrast microscope amplifies the slight differences between cells and the surrounding medium (background) to make the cells highly distinguishable. Ques 0 / 0 pts tion 8 Your Answer: What is the distinguishing feature of dark field microscopy? instead of light passing through the sample, it reflects off of it at an angle This study source was downloaded by from CourseH on :11:38 GMT -05:00 4/29/23, 8:38 PM M3: Module 3 Review: Essential Microbiology with Lab-2021-Stepp Unlike bright field or phase contrast microscopy where light passes directly through the sample, dark field microscopy reflects light off of the specimen at an angle. The resulting image is an exceptionally dark background and a vibrant specimen. Ques 0 / 0 pts tion 9 Your Answer: Unlike brightfield microscope, fluorescence microscopes illuminate samples through what spectrum? UV spectrum The energy of the incoming light is in the form of the ultraviolet (UV) spectrum. Ques 0 / 0 pts tion 10 Your Answer: What is the primary difference between TEM and SEM? for TEM, electrons pass through a thin slice of the specimen for SEM, electrons reflect off the gold/paladium covered shell of a specimen, making a 3D model This study source was downloaded by from CourseH on :11:38 GMT -05:00 4/29/23, 8:38 PM M3: Module 3 Review: Essential Microbiology with Lab-2021-Stepp During transmission electron microscopy the electron passes through the sample whereas during scanning electron microscopy the electron is reflected off the sample creating a three dimensional ‘shell’ model of the specimen.