BACE Microscopy and Imaging Techniques 1 — Questions and Answers
Question 1: What is the total magnification when using a 10x eyepiece with a 40x objective lens on a compound microscope?
- 400x (Correct answer)
- 50x
- 4x
- 4000x
Correct answer: 400x
Total magnification is calculated by multiplying the eyepiece magnification (10x) by the objective lens magnification (40x), giving 400x.
Question 2: Which type of microscopy uses fluorescent dyes or proteins to visualize specific cellular structures?
- Fluorescence microscopy (Correct answer)
- Bright-field microscopy
- Phase-contrast microscopy
- Dark-field microscopy
Correct answer: Fluorescence microscopy
Fluorescence microscopy uses fluorescent labels that emit light at specific wavelengths when excited, allowing visualization of tagged structures.
Question 3: What is the purpose of immersion oil used with a 100x oil-immersion objective lens?
- To increase resolution by eliminating refractive index differences between the lens and slide (Correct answer)
- To lubricate the objective lens
- To stain the specimen for better visibility
- To cool the objective lens during use
Correct answer: To increase resolution by eliminating refractive index differences between the lens and slide
Immersion oil has the same refractive index as glass, preventing light refraction at the lens-air interface and improving resolution.
Question 4: Which microscopy technique is most suitable for observing live, unstained, transparent specimens?
- Phase-contrast microscopy (Correct answer)
- Bright-field microscopy
- Electron microscopy
- Confocal microscopy
Correct answer: Phase-contrast microscopy
Phase-contrast microscopy converts differences in light phase (caused by specimen thickness/density) into visible contrast without requiring staining.
Question 5: What does the term 'resolution' refer to in microscopy?
- The minimum distance between two points that can be distinguished as separate (Correct answer)
- The total magnification of the microscope
- The brightness of the image
- The depth of field of the objective lens
Correct answer: The minimum distance between two points that can be distinguished as separate
Resolution is the ability of a microscope to distinguish two closely spaced points as separate objects; higher resolution means finer detail is visible.
Question 6: Which staining technique uses crystal violet and iodine to differentiate bacteria into two groups based on cell wall structure?
- Gram staining (Correct answer)
- Acid-fast staining
- Giemsa staining
- Hematoxylin and eosin staining
Correct answer: Gram staining
Gram staining differentiates bacteria into gram-positive (purple) and gram-negative (pink) based on cell wall peptidoglycan content.
BACE Microscopy and Imaging Techniques 1
What is the total magnification when using a 10x eyepiece with a 40x objective lens on a compound microscope?