Biology Lab Chapter 2

Question 0

Length

Answer 0

Metric units of length measurement include the:
Meter (m)
Centimeter (cm)
Millimeter (mm)
Micrometer (ym) see symbol
Nanometer (nm)

Question 1

Metric system

Answer 1

Is the standard system of measurement in the sciences, including biology, chemistry and physics. It has tremendous advantages because all conversions, whether for volume, mass (weight), or length, can be in units of ten.

Question 2

The prefixes:
milli- (10-30)
Micro- (10-6) and
Nano (10-9)

Answer 2

Are used with length, weight and volume.

Question 3

Weight

Two metric units of weight are the:

Answer 3

Gram (g) and the milligram (mg).

Question 4

Volume

Two metric units of volume are the:

Answer 4

Liter (l)
Milliliter (ml)
One liter = 1,000 ml.

Question 5

Temperature

There are two temperature scales; They are:

Answer 5

Fahrenheit (F) and Celsius (centigrade, C) scales.

Scientists use the Celsius scale.

Question 6

Microscopy.

Because biological objects can be very small, we often use a microscope to view them.

Answer 6

There are many kinds of microscopic instruments.

Question 7

Two kinds of light microscopes and two kinds of electron microscopes are listed:

Answer 7

Light microscopes and electron microscopes.

Question 8

Light microscopes use light rays passing through the lenses to magnify the object. The two light microscopes are:

Answer 8

The stereo microscope (dissecting microscope), designed to study entire objects in three dimensions at low magnification.

The compound light microscope is used for examining small or thinly sliced sections of objects under higher magnification.

Question 9

Compound refers to:

Answer 9

The use of two sets of lenses.
Ocular lenses located near the eyes and
Objective lenses located near the object.

Question 10

Electron microscopes uses beams of electrons to magnify the object. The beams are focused on a photographic plate by means of electromagnet. Two types are:

Answer 10

Transmission electron microscope is analogous (comparable) to the compound light microscope.

The scanning electron microscope is analogous to the dissecting light microscope. It gives an image of the surface and the dimensions of and object.

Question 11

Resolution

Answer 11

Is the minimum distance between two objects at which they can still be seen or resolved, as two separate objects.

Question 12

The use of high-energy electrons rather for than light gives electron microscopes a much greater resolving power since two objects that are much closer together can still be distinguished as separate points.

Answer 12

True

Question 13

Compound Light Microscope

Answer 13

Glass lenses
Illumination by visible light
Resolution =(symbol) 200 mm
Magnifies to 2,000x
Costs up to tens of thousands of dollars

Question 14

Transmission Electron Microscope

Answer 14

Electromagnetic lenses
Illumination due to beam of electrons
Resolution =(symbol) 0.1 nm
Magnifies to 1,000,000x
Costs up to hundreds of thousands of dollars

Question 15

Which two types of microscopes view the surface of an object

Answer 15

The stereomicroscope (dissecting) and scanning electron microscope.

Question 16

Which two types of microscopes view objects that have been sliced and treated to improve contrast?

Answer 16

Compound light microscope and transmission electron microscope.

Question 17

Of the microscopes just mentioned, which one resolves the greater amount of detail?

Answer 17

The electron microscope.

Question 18

Stereomicroscope (dissecting microscope)

Answer 18

Allows you to view objects in 3 dimensions at low magnifications. It is used to study entire small organisms, any object requiring lower magnification, and opaque objects that can be viewed only by reflected light.

Question 19

Rules for Microscope Use

Answer 19

1. The lowest power objective (scanning or low) should be in position, at both the beginning and the end of microscope use.
2. Use only lens paper for cleaning lenses.
3. Do not tilt the microscope as the eyepieces could fall out, or wet mounts could be ruined.
4. Keep the stage clean and dry to prevent rust and corrosion.
5. Do not remove parts of the microscope.
6. Keep the microscope dust-free by covering it after use.
7. Report any malfunctions.

Question 20

Compound light microscopes are parfocal; that is, once the object is in focus to with the lowest power, it should also be almost in focus with the higher power.

Answer 20

True

Question 21

Total Magnification

Answer 21

Is calculated by multiplying the magnification of the ocular lens (eyepiece) by the magnification of the objective lens. The magnification of a lens is imprinted on the lens casing.

Question 22

Field of view

Answer 22

Is the circle visible through the lenses.

Question 23

Diameter of field.

Answer 23

Is the length of the field from one edge to the other.

Question 24

Does low power or high power have a larger field of view (one that allows you to see more of the object)?

Answer 24

A

Question 25

Which has a smaller field but magnifies to a greater extent?

Answer 25

A

Question 26

To locate small objects on a slide, first find them under ________; then place them in the center of the field before rotating to _________.

Answer 26

A