Chapter 1-2 Measurements and Microscopes

What is the metric unit for length?

meter (m)

What is the metric unit for volume?

liter (L)

What is the metric unit for mass?

gram (g)

What is the metric unit for temperature?

Celsius (°C)

How many centimeters are in 1 inch?

2.54 cm

How many millimeters are in 1 meter?

1000 mm

How many milliliters are in 1 liter?

1000 mL

What is the definition of mean?

average value of a dataset

What is the definition of median?

middle value when data is ordered

What is the definition of range?

maximum value minus minimum value

What does standard deviation measure?

how spread out data is from the mean

What is accuracy in measurement?

how close a measurement is to the true value

What is precision in measurement?

how close repeated measurements are to each other

What are the components of dataset analysis?

mean, median, range, standard deviation

What is the difference between accuracy and precision?

accuracy = correctness; precision = repeatability

What is the function of the ocular lens?

Where you look through; usually 10x

What do objective lenses provide?

Magnification (4x, 10x, 40x)

What is the role of the condenser in microscopy?

Focuses light onto specimen

What does the iris diaphragm do?

Adjusts amount of light

What does the stage do in a microscope?

Holds slide

What is the coarse focus used for?

Large focusing adjustments; low power only

What is the fine focus used for?

Small adjustments; sharpens image

What is the function of the nosepiece?

Holds objective lenses; rotates

How is the orientation of the letter 'e' under a compound microscope?

Upside down and reversed

How is the orientation of the letter 'e' under a dissecting microscope?

Right side up

How does the image move under a compound microscope?

Image moves opposite of specimen movement

How does the image move under a dissecting microscope?

Image moves same direction as movement

What happens to brightness when switching from low to high power?

Decreases brightness

How is total magnification calculated?

Ocular × objective lens

Which objective has the largest field of view?

4x has largest field of view (approx 10× larger)

Which objective has the greatest depth of field?

Low-power objective

Are all colored threads in focus under high power?

No; only low power shows all threads because depth of field is greater

What is the best objective to locate a specimen?

4x because it provides widest field of view

Does maximum illumination always give the best image?

No; too much light reduces contrast

Which magnification needs the most illumination?

High-power objectives

Why must specimens be thin under a compound microscope?

Allows light to pass through for viewing

Why are stains used in microscopy?

Increases contrast to see structures

What dye is used in the lab?

Methylene blue

What structure is stained most by methylene blue?

Nucleus

What is the difference between a compound and a dissecting microscope?

Compound: higher magnification, thin specimens; dissecting: lower magnification, 3D objects

What is the importance of microscopes?

To observe structures too small for the naked eye

How is specimen size calculated?

Using stage and ocular micrometers

What is the difference between plant and animal cells?

Plants: cell wall, chloroplasts, vacuole; animals: no cell wall, no chloroplasts

What are the microscope care rules?

Carry with two hands, clean lenses with lens paper only, store on low power