BACE Microscopy and Imaging Techniques 2 — Questions and Answers
Question 1: In confocal microscopy, what is the primary advantage over conventional fluorescence microscopy?
- It eliminates out-of-focus fluorescence to produce sharper optical sections (Correct answer)
- It requires no fluorescent labels
- It provides lower magnification
- It uses visible light instead of laser light
Correct answer: It eliminates out-of-focus fluorescence to produce sharper optical sections
Confocal microscopy uses a pinhole aperture to exclude out-of-focus light, enabling thin optical sectioning and three-dimensional imaging.
Question 2: What is the correct procedure when switching from a lower to a higher power objective lens on a microscope?
- Rotate the nosepiece while watching from the side, then use only the fine focus adjustment (Correct answer)
- Use the coarse focus adjustment to refocus the image
- Increase the light intensity before switching objectives
- Remove the slide and reposition it before switching
Correct answer: Rotate the nosepiece while watching from the side, then use only the fine focus adjustment
When switching to a higher power objective, only the fine focus is used since the microscope is parfocal and coarse adjustment could damage the lens or slide.
Question 3: Which component of a compound microscope controls the amount of light passing through the specimen?
- Iris diaphragm (Correct answer)
- Condenser
- Objective lens
- Eyepiece
Correct answer: Iris diaphragm
The iris diaphragm is an adjustable aperture in the condenser that controls the amount and angle of light illuminating the specimen.
Question 4: What type of electron microscopy is used to examine the internal ultrastructure of thin-sectioned specimens?
- Transmission electron microscopy (TEM) (Correct answer)
- Scanning electron microscopy (SEM)
- Fluorescence electron microscopy
- Confocal electron microscopy
Correct answer: Transmission electron microscopy (TEM)
TEM passes electrons through thin specimens to create high-resolution images of internal cellular structures at the nanometer scale.
Question 5: Why should microscope lenses be cleaned only with lens paper and lens cleaning solution?
- To prevent scratching the lens coating and avoid contamination with oils from other materials (Correct answer)
- To make cleaning faster and more efficient
- Because lens paper is sterile and prevents biological contamination
- To apply additional optical coatings to the lens surface
Correct answer: To prevent scratching the lens coating and avoid contamination with oils from other materials
Lens paper is lint-free and non-abrasive, and lens solution dissolves oils without damaging the delicate anti-reflective coatings on microscope lenses.
Question 6: What is the function of the condenser in a compound light microscope?
- To focus light onto the specimen to maximize illumination and resolution (Correct answer)
- To magnify the final image seen by the observer
- To hold the objective lenses in position
- To adjust the magnification of the eyepiece
Correct answer: To focus light onto the specimen to maximize illumination and resolution
The condenser focuses light from the illuminator onto the specimen, optimizing the cone of light for the objective lens being used.
BACE Microscopy and Imaging Techniques 2
In confocal microscopy, what is the primary advantage over conventional fluorescence microscopy?