BIO 113 Chapter 3 Flashcards

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Questions and Answers

What is one of the most important tools in the biological sciences?

The microscope

A typical compound microscope extends the vision of the observer more than __________ times.

one hundred

What type of microscope is most commonly used?

The light microscope

What do compound microscopes use to magnify specimens?

A set of two lenses Signup and view all the answers

An example of the compound light microscope is the __________.

Bright field microscope Signup and view all the answers

What does the compound dark field microscope do?

Reflects light off the specimen Signup and view all the answers

What type of light does the fluorescence microscope use?

UV light Signup and view all the answers

What is the primary function of the phase contrast microscope?

Accentuates minute differences in structures Signup and view all the answers

What does the norman ski microscope use to study structures?

Differences in the refractive index Signup and view all the answers

What do electron microscopes use to magnify a specimen?

Beams of electrons Signup and view all the answers

What is the transmission electron microscope used for?

Extremely thin sections of specimens Signup and view all the answers

What feature does the scanning electron microscope provide?

Three-dimensional views of objects Signup and view all the answers

What connects the ocular to the body tube in a compound microscope?

Draw tube Signup and view all the answers

What serves as a handle on a microscope?

Arm Signup and view all the answers

What is the function of the nosepiece in a microscope?

Revolves and holds the objectives Signup and view all the answers

What do the lower lenses attached to the nosepiece of a microscope called?

Objectives Signup and view all the answers

What does the fine adjustment knob do?

Adjusts specimen into final focus Signup and view all the answers

What is the illuminator's role in a microscope?

Serves as illumination for the specimen Signup and view all the answers

What does the iris diaphragm regulate?

Light entering the microscope Signup and view all the answers

The distance between the objective lens and the specimen is called the __________.

working distance Signup and view all the answers

What is the field of view in microscopy?

The circular field seen through the ocular Signup and view all the answers

How does magnification depend on objectives?

It is the product of the power of the ocular and objective Signup and view all the answers

Most microscopes are __________.

parfocal Signup and view all the answers

Study Notes

Microscopes in Biological Sciences

Microscopes are essential tools commonly used in biological research.
A typical compound microscope magnifies objects over one hundred times, while transmission electron microscopes can magnify up to one million times.

Types of Microscopes

The most common type is the light microscope, featuring a single lens in its simplest form.
Compound microscopes utilize two lenses for enhanced magnification.
Bright field microscopes allow light to pass directly through specimens, creating a dark appearance against a light background.
Dark field microscopes reflect light off specimens, making them appear bright against a dark background.
Fluorescence microscopes employ UV light and fluorescent dyes to visualize specimens.
Phase contrast microscopes enhance minute structural differences within specimens using regular light.
Norman ski microscopes analyze structures by differences in refractive index.
Electron microscopes use electron beams for magnification; they include transmission electron and scanning electron microscopes for thin sections and three-dimensional views, respectively.
Scanning transmission electron microscopes combine features of both scanning and transmission microscopies.

Components of Compound Microscopes

Ocular (eyepiece): The lens through which specimens are viewed.
Draw tube: Connects the ocular to the body tube.
Body: Holds the nosepiece and includes the draw tube.
Arm: Serves as a handle for maneuvering the microscope.
Nosepiece: Revolves to hold and switch between objectives.
Objectives: Lenses attached to the nosepiece, coming in various power options:
- Scanning objective: Shortest lens for low magnification.
- Low power objective: Used for initial focusing on specimens.
- High power objective: Provides fine focusing details.
- Oil immersion objective: Utilizes immersion oil for enhanced magnification.

Microscopic Functionality

Stage: Platform for placing slides.
Illuminator: Provides light to illuminate samples.
Iris diaphragm: Regulates light intensity entering the microscope.
Condenser: Focuses light on the specimen from below the stage.
Coarse adjustment knob: Used for initial focusing; applicable only with scanning and low power objectives.
Fine adjustment knob: Refines focus on specimens.

Microscopy Techniques and Considerations

Many microscopes are parfocal, allowing for focus retention when switching objectives.
Magnification results from multiplying the power of the ocular and objective lenses.
Resolving power distinguishes closely placed objects and is influenced by lens design and quality.
When observing specimens, slide movement is inversely related to image movement.
Proper illumination is crucial; improper settings can lead to poor imaging and strain on the eyes.
The working distance, or distance between the lens and specimen, decreases as magnification increases, requiring more light.
The field of view changes with magnification levels; higher magnification results in a smaller field of view.
Microscopic lenses have a specific plane of focus, with an associated depth of field that decreases under greater magnification.
Oil immersion objectives are valuable for examining small organisms and detailed specimen characteristics.
Wet mounts are prepared slides for viewing fresh specimens under a microscope.

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Test your knowledge with these flashcards from BIO 113, Chapter 3. Explore the essential concepts about microscopes, their significance in biological sciences, and the various types available. Perfect for reinforcing your understanding of microscopy.