Microscopy PDF

## Microscopy ### Vital Examination **1. What is the primary purpose of vital examination?** * To examine living cells without damaging them. **2. Which of the following dyes is mentioned as being used in vital examinations?** * Neutral red. **3. What type of microscope is NOT used in vita...

## Microscopy ### Vital Examination **1. What is the primary purpose of vital examination?** * To examine living cells without damaging them. **2. Which of the following dyes is mentioned as being used in vital examinations?** * Neutral red. **3. What type of microscope is NOT used in vital examinations?** * Electron microscope. ### Phase-Contrast Microscopy **4. What is the main function of a phase-contrast microscope?** * To enhance contrast between different parts of a cell. **5. How does a phase-contrast microscope create contrast?** * By converting differences in the phase of light into differences in light intensity. ### Interference Microscopy **1. What type of microscope operates on the same principle as interference microscopy?** * Phase-contrast microscope. **2. What materials are typically added in front of the condenser in an interference microscope?** * Calcite or quartz plates. **3. How does the interference microscope create an image?** * By creating a phase difference between two light beams. **4. What causes the phase difference between the two beams in interference microscopy?** * The thickness of the object and the refractive index of the medium. **5. What type of samples can be examined using interference microscopy?** * Unstained preparations. ### Dark Field Microscopy **1. What is the main modification in dark field microscopy?** * Attachment of a special condenser. **2. In dark field microscopy, how are the illuminating rays directed?** * From the side of the object. **3. Why is it difficult to examine living cells under a microscope without fixation?** * Their light refraction coefficients are similar. **4. What is the purpose of fixing and staining cells before microscopic examination?** * To enhance visibility of details **5. Which types of microscopes are mentioned as being used to examine fixed and stained cells?** * Normal light, fluorescent, X-ray, and electron microscopes. ### Light Microscopy **1. Which of the following parts is NOT included in the mechanical part of a light microscope?** * Objective. **2. What is the function of the condenser in a light microscope?** * To focus light rays onto the object. **3. What is the primary feature that determines the effectiveness of a microscope?** * Resolution. **4. The visible wavelengths used in light microscopy typically range between:** * 0.4 µm and 0.7 µm. **5. Objects that are closer than which distance cannot be resolved by normal light microscopes?** * 0.2 µm. ### Fluorescence Microscopy **6. What type of microscope uses fluorescent rays with wavelengths shorter than 0.4 µm?** * Fluorescence microscope. **7. If the objective is moved closer to the object, what happens to the resolving power?** * It increases. **1. What is the primary function of a fluorescence microscope?** * To examine objects stained with fluorescent dyes. **2. What type of light source is commonly used in fluorescence microscopes?** * Mercury vapor bulbs. **3. Which optical material is used in fluorescence microscopes to avoid absorption of ultraviolet light?** * Quartz. **4. What size of objects can fluorescence microscopes examine?** * 0.1 µm. **5. What is the role of the first series of filters in a fluorescence microscope?** * To trap light from the source and allow only the wavelengths absorbed by the dye to pass. **6. In a fluorescence microscope, what do the second series of filters do?** * Block reflected rays and pass only higher wavelength rays from the object. **7. How does the fluorescence microscope differ from a normal light microscope?** * It uses a different light source and some optical parts. ### Polarizing Microscopy **1. What is the primary purpose of the polarizer in a polarizing microscope?** * To polarize the beam from the light source. **2. What happens when the analyzer is rotated 360°?** * The field alternates between dark and light every 180°. **3. When the axes of the polarizer and analyzer are perpendicular to each other, what is the appearance of the microscope field?** * Dark. **4. How does an anisotropic material affect incident light in a polarizing microscope?** * It delays and translates the incident light. **5. What is the main advantage of using a polarizing microscope?** * It increases the contrast of certain objects. ### X-Ray Microscopy **What is the primary use of X-ray microscopy?** * To study the structure of atoms and molecules smaller than 1 nm. **The mechanism of an X-ray microscope is based on which principle?** * Diffraction. **What do the concentric dots or lines in X-ray diffraction micrographs represent?** * The structural features of the object. **What type of lenses are used in an X-ray microscope to direct X-rays onto the object?** * Electronic lenses. **What is the purpose of the fine-grained photographic plate or fluorescent screen in an X-ray microscope?** * To capture the X-rays that leave the object. **How are X-ray diffraction micrographs obtained?** * By evaluating the concentric dots and lines formed on a plate or screen. ### Electron Microscopy **What is the theoretical separation power of an electron microscope?** * 0.002 nm. **What is the practical separation power of electron microscopes?** * 0.1 nm. **What type of electron microscope provides two-dimensional images?** * Transmission Electron Microscope (TEM). **In Scanning Electron Microscopy (SEM), how are electrons used to obtain images?** * They are scattered on the surface of the sample. **What is the purpose of creating a vacuum in a Transmission Electron Microscope (TEM)?** * To prevent deflection of electrons by air molecules. **What is used to focus the electron beam in a TEM?** * Magnetic coils. **What material is commonly used to coat samples for SEM?** * Platinum. **Which of the following statements is true about electron microscopes?** * They can achieve higher resolution due to the shorter wavelength of electrons. ### Cell Culture Techniques **1. What is the primary purpose of cell culture techniques?** * To solve problems related to cell biology. **2. What type of tissues are commonly stored for cell culture?** * Embryonic tissues. **3. Which component is commonly added to cell culture media to maintain optimum pH?** * Bicarbonate. **4. What is the typical pH maintained in cell culture media?** * 7.4 **5. Why is it important to prepare the salt concentration of the culture medium isotonically?** * To avoid osmotic imbalance. **6. What role do vitamins and hormones play in cell cultures?** * They act as cofactors in cell growth. **7. Which of the following techniques is used to analyze cell components?** * All of the above. **8. What is the purpose of using a pH indicator in cell culture media?** * To determine pH fluctuations and bacterial contamination. **1. What is the first step in the technique of separating cells into sections?** * Homogenization of cell boundaries. **2. Which method is used to separate organelles or macromolecules in cell homogenate based on mass?** * Rate zonal centrifugation. **3. What is the purpose of using sucrose in the homogenization process?** * To prevent damage to organelles. **4. In what type of solution is homogenization typically carried out?** * Buffer or sucrose solution. **5. Why is the pH and content of buffer solutions important in homogenization?** * To ensure effective separation of organelles. **6. What is the purpose of centrifugation methods after homogenization?** * To separate homogenized tissues or cells. **7. Which technique is commonly used to disrupt cells in homogenization?** * Ultracentrifugation. * **8. What should be selected specific to the macromolecule to be obtained in homogenization?** * Buffer series.