Mastering Quiz 02 Microscopy

Mastering Quiz 02 (Microscopy) To understand how points are awarded, read the Grading Policy for this assignment. Chapter 3 Multiple-Choice Question 12 Part A Which microscope uses visible light? ANSWER: differential interference contrast microscope fluorescence microscope scanning acoustic microscope scanning electron microscope confocal microscope Correct Chapter 3 Multiple-Choice Question 13 Part A Which microscope achieves the highest magnification and greatest resolution? ANSWER: phase-contrast microscope darkfield microscope electron microscope fluorescence microscope compound light microscope Correct Chapter 3 Multiple-Choice Question 11 Part A Which microscope is used to see internal structures of cells in a natural state? ANSWER: electron microscope fluorescence microscope compound light microscope darkfield microscope phase-contrast microscope Correct Chapter 3 Multiple-Choice Question 14 Part A In using this microscope, the observer does NOT look directly at an image through a lens. ANSWER: fluorescence microscope darkfield microscope phase-contrast microscope compound light microscope electron microscope Correct Chapter 3 Multiple-Choice Question 15 Part A This microscope produces an image of a light cell against a dark background; internal structures are NOT visible. ANSWER: darkfield microscope phase-contrast microscope electron microscope compound light microscope fluorescence microscope Correct Observing Microorganisms Through a Microscope – Foundation Figure 3.2 Most microorganisms are too small to be viewed with the unaided eye. Different types of microscopes have been developed that allow us to visualize these small organisms. Th structure depends on the size of the organism and the particular information about it that you are looking for. For viewing eukaryotic cells and bacteria, light microscopes are ge view viruses and the internal structure of bacterial cells, as well as fine structural details of eukaryotic cells, scanning electron microscopes and transmission electron microscop resolution. However, preparing specimens to be viewed with these microscopes requires a greater investment in time and technique. Scanning electron microscopes are espec three-dimensional perspective of the organism’s overall shape. Transmission electron microscopy is useful for viewing fine structural details in cross sections of microorganisms the object; other considerations include how much time and effort are needed to prepare the specimen for microscopy, whether you will be viewing living or fixed cells, and whe the size of microorganisms and viruses, you will need an understanding of the following metric units: millimeters, micrometers, nanometers, and picometers. Read through Foundation Figure 3.2, and then complete the activity and questions below. Part A - Selecting the Most Appropriate Method of Viewing This activity asks you to sort items according to the most appropriate method for viewing. For each of the following items, indicate which viewing method is most appropriate–the unaided eye, light microscopy, scanning electron microscopy, or trans Hint 1. Unaided eye Assuming normal vision, the unaided eye can resolve objects greater than 0.20 millimeters. This is about the size of a human ovum, which is the only human cell that ca Hint 2. Light microscope Light microscopes, such as the typical brightfield microscope used in your microbiology lab, can be used to view objects from 200 nanometers to 10 millimeters in size. as fixed and stained microorganisms. Hint 3. Scanning electron microscope Scanning electron microscopes can be used to view objects from 10 nanometers to 1 millimeter in size. Objects or microorganisms must be coated with metal and cann excellent for viewing surface features as well as providing a three-dimensional view of a cell. Hint 4. Transmission electron microscope A transmission electron microscope can be used to view objects from 10 picometers to 100 micrometers in size. Electron micrographs provide an excellent view of the fi sectioned into slices and stained. Cells cannot be viewed in the living state. ANSWER: Reset ! ! ! ! ! ! ! ! ! confirming the 9 + 2 microtubule arrangement in a eukaryotic flagellum viewing the three-dimensional shape of a protozoan and the arrangement and distribution of cilia on its surface examining a blood smear for the presence of malarial parasites examining your cat for the presence of fleas examining a clinical specimen, such as a sputum smear, for the presence of bacteria determining the three-dimensional shape and arrangement of bacterial cells viewing a cross section of poliovirus (30 nm) viewing ribosomes (20 nm) within a bacterial cell viewing the layers of the gramnegative cell wall in cross section Correct You have correctly associated each of the items with the most appropriate viewing method. Recall that although the size of an object is a major consideration in cho other factors: how much time and effort are needed to prepare the specimen for microscopy, whether you will be viewing living or fixed cells, and whether you want Part B - Relative Sizes of Microorganisms To select the appropriate microscope, you need to understand the relative sizes of eukaryotic cells, prokaryotic cells, intracellular structures, and viruses. This activity asks Drag the appropriate image to each box, arranging the items in size from smallest to largest. Hint 1. Metric conversions: metric units of length To compare sizes of different objects, convert all of the sizes provided to the same units. Metric Unit Meaning of Prefix Metric Equivalent U.S. Equivalent 1 kilometer (km ) kilo = 1000 1000 m = 103 3280.84 1 meter ( m) m 1 decimeter (dm ) deci = 1/10 1 centimeter ( cm) centi = 1/100 0.1 m = 10 −1 0.394 in ; 1 in = 2.54 cm m 1 millimeter (mm ) milli = 1/1000 0.001 m = 10 1 micrometer ( µ micro = 1/1,000,000 0.000001 m = 1 nanometer (nm ) nano = 1/1,000,000,000 0.000000001 m = 1 picometer (pm ) pico = 1/1,000,000,000,000 0.000000000001 m =10 m) −3 ft or 1.09 yd 3.94 in m 0.01 m = 10−2 ft or 0.62 mi ; 1 mi = 1.61 km 39.37 in or 3.28 Standart unit of length m 10−6 m 10−9 m −12 m Hint 2. Metric conversions: converting nanometers to micrometers, or micrometers to nanometers To convert nanometers to micrometers, divide the measurement in nanometers by 1000. To convert micrometers to nanometers, multiply the measurement in micromet Hint 3. Metric conversions: converting micrometers to millimeters or millimeters to micrometers To convert micrometers to millimeters, divide the measurement in micrometers by 1000. To convert millimeters to micrometers, multiply the measurement in millimeters ANSWER: Reset Correct You have correctly arranged these images from smallest to largest. The smallest image depicts plasmids from an E. coli cell. These circles of DNA measure about 2 an adenovirus, measuring about 50 nanometers (or 0.05 micrometers) in diameter. The third image depicts bacterial cells measuring about 1 micrometer by 5 micro measuring approximately 7 micrometers by 20 micrometers. The largest image is a flatworm parasite known as Clonorchis sinensis, measuring approximately 20 m The metric units most appropriate for expressing the size of microorganisms include the millimeter (mm), the micrometer, and the nanometer (nm). Eukaryotic and bacterial cell expressed in nanometers. The next two parts involve measurement conversions. Part C - Metric Measurements and Conversions (Micrometers and Nanometers) Chlamydia trachomatis elementary bodies measure approximately 0.25 micrometers in diameter. What is this measurement expressed in nanometers (nm)? Hint 1. Metric conversions: metric units of length Metric Unit Meaning of Prefix Metric Equivalent U.S. Equivalent 1 kilometer (km ) kilo = 1000 1000 m = 103 3280.84 1 meter ( m) 1 decimeter (dm ) deci = 1/10 1 centimeter ( cm) centi = 1/100 m 39.37 in or 3.28 0.1 m = 10−1 3.94 in m 0.01 m = 10−2 milli = 1/1000 0.001 m = 10 1 micrometer ( µ micro = 1/1,000,000 0.000001 m = 1 nanometer (nm ) nano = 1/1,000,000,000 0.000000001 m = 1 picometer (pm ) pico = 1/1,000,000,000,000 0.000000000001 m =10−12 −3 ft or 1.09 yd 0.394 in ; 1 in = 2.54 cm m 1 millimeter (mm ) m) ft or 0.62 mi ; 1 mi = 1.61 km Standart unit of length m 10−6 m 10−9 m m Hint 2. Metric conversions: converting nanometers to micrometers or micrometers to nanometers To convert nanometers to micrometers, divide the measurement in nanometers by 1000. To convert micrometers to nanometers, multiply the measurement in micromet ANSWER: 25 nm 2.5 nm 250 nm 2500 nm 25,000 nm Correct This is correct. To obtain the measurement in nanometers, you have multiplied the measurement in micrometers by 1000. Part D - Metric Measurements and Conversions (Millimeters and Micrometers) A paramecium is approximately 150 micrometers in length. What is this measurement expressed in millimeters (mm)? Hint 1. Metric conversions: metric units of length Metric Unit Meaning of Prefix Metric Equivalent U.S. Equivalent 1 kilometer (km ) kilo = 1000 1000 m = 103 3280.84 1 meter ( m) 1 decimeter (dm ) deci = 1/10 m ft or 0.62 mi ; 1 mi = 1.61 km Standart unit of length 39.37 in or 3.28 0.1 m = 10−1 3.94 in m ft or 1.09 yd 1 centimeter ( cm) centi = 1/100 0.01 m = 10−2 0.394 in ; 1 in = 2.54 cm m 1 millimeter (mm ) milli = 1/1000 0.001 m = 10 1 micrometer ( µ micro = 1/1,000,000 0.000001 m = 1 nanometer (nm ) nano = 1/1,000,000,000 0.000000001 m = 1 picometer (pm ) pico = 1/1,000,000,000,000 0.000000000001 m =10−12 m) −3 m 10−6 m 10−9 m m Hint 2. Metric conversions: converting micrometers to millimeters or millimeters to micrometers To convert micrometers to millimeters, divide the measurement in micrometers by 1000. To convert millimeters to micrometers, multiply the measurement in millimeters ANSWER: 0.015 mm 0.15 mm 15 mm 1.5 mm 1500 mm Correct This is correct. To obtain the measurement in millimeters, you have divided the measurement in micrometers by 1000. Part E - Labeling Parts of the Microscope To communicate effectively about use of the microscope in the laboratory setting, you need to know the parts of the microscope. This activity asks you to label the parts of Drag the label to the appropriate part of the microscope. Hint 1. Ocular and objective lenses Ocular refers to the eye. The ocular lens is the lens closest to your eye, the one you look through. It is also known as the eyepiece. The objective lens is closest to the object that you’re viewing on the slide. There are usually several objective lenses to choose from, each providing a different magnific switch from one to another. Hint 2. Coarse and fine focus knobs The coarse focus knob is the larger knob, usually located on the side, just above the base of the microscope. The fine focus knob is most often a small knob located lat coarse focus knob. Hint 3. Diaphragm and condenser These two microscope parts are located immediately beneath the stage. The condenser is a lens that focuses the light from the illuminator onto the specimen. It can oft immediately below. The diaphragm controls the amount of light coming through the condenser. Most often, the diaphragm lever is below the condenser lens. Hint 4. Base, arm, and body tube The base of the microscope is the sturdy platform on which the microscope sits. In most microscopes, the illuminator (light source) is located within the base. The arm of the microscope connects the base with the body tube of the microscope. Always carry a microscope with two hands, one holding the arm and the other plac through which light travels between the objective lens and the ocular lens. In most modern microscopes this is not a straight path, so the body tube includes prisms, wh ANSWER: Reset Help Ocular lenses Body tube Objective lenses Arm Stage Condenser lens Coarse focus knob Diaphragm Illuminator Base Fine focus knob Correct You have correctly identified each of the microscope parts. This will help you communicate with your instructor and other students during lab activities involving the Part F - Describing Functions of Parts of the Microscope In addition to knowing the names of the parts of the compound light microscope, you also need to know the functions of these parts. This activity asks you to match the app Match each microscope part with its function. Drag the labels in the left column to indicate the microscope part that performs each function listed on the right. Hint 1. Ocular and objective lenses Both of these lenses contribute to the total magnification. The objective lens produces an image within the body tube of the microscope, which is then further magnified Hint 2. What happens to the light before it reaches the specimen on the slide? There are two structures (condenser lens and diaphragm) below the stage through which light passes before reaching the specimen on the slide. One of these structure adjusted to increase or reduce the amount of light for optimum viewing. The other structure focuses light onto the slide. Hint 3. Why are there two focusing knobs? Microscopes have both a coarse focus knob and a fine focus knob. These knobs move the stage closer or farther from the objective lens to obtain the sharpest image, is more suitable for bringing an object into focus initially using the low-power objective lens. The other enables small, discrete adjustments to the sharpness of the imag objective is in place. ANSWER: Reset ! 1. Fine focus knob :used after initial focusing to sharpen the image ! 2. Diaphragm :controls how much light from the illuminator reaches the specimen ! Help ! 3. Ocular lens :lens that you look through ! 4. Condenser lens :used to focus the light from the illuminator onto the slide ! 5. Objective lens :lens that is closest to the slide and provides initial magnification of a specimen ! 6. Stage :platform on which the slide is placed for viewing 7. Coarse focus knob :used for initial focusing; should never be used when the high-power objective lens or oil immersion objective lens is in place Correct You have correctly matched the microscope parts with their functions. Knowing these functions will help you use the microscope correctly during laboratory activities Score Summary: Your score on this assignment is 100%. You received 10 out of a possible total of 10 points.