Chapter 4 - Methods for Examining Biological Evidence

Question 1

Microscope

Answer 1

Optical instrument used for magnifying
small objects.

Question 2

lens

Answer 2

A curved optical component, usually made from glass or other transparent materials, which is used to form an image by focusing light beams

Question 3

Ocular lens

Answer 3

Lens in a microscope closest to the viewer. known as the eyepiece

Question 4

Sample stage

Answer 4

Component of the microscope that holds and moves the sample being observed

Question 5

Objective lens

Answer 5

Lens in a microscope closest to the object being viewed (10x)

Question 6

Comparison microscope

Answer 6

form of microscopy that consists of two separate and complete microscopes that are joined together at the
eyepiece, allowing a simultaneous view of two different samples

Question 7

Electron microscopy

Answer 7

Form of microscopy that uses an electron beam to “illuminate” a sample, allowing magnifications of up to several million times

Question 8

Scanning electron microscopy

Answer 8

Microscope that forms an image by moving a focused beam of electrons across a sample and detecting the electrons scattered by the sample

Question 9

Transmission electron microscopy

Answer 9

Microscopic technique that employs an electron beam passed directly through a sample to produce a cross-sectional image with very small features

Question 10

Contrast

Answer 10

The difference between a feature of a microscopic sample compared with other features

Question 11

Concave

Answer 11

An inner rounded surface, such as the inner portion of a bowl

Question 12

Convex

Answer 12

An outer rounded surface, such as the outer portion of a bow

Question 13

Density

Answer 13

A physical quantity of mass per unit volume

Question 14

Depth of field/depth of focus

Answer 14

Term that refers to the thickness of a sample that can be
simultaneously viewed in focus and depends upon magnification where the depth of focus increases when the magnification of the lenses increases

Question 15

Electromagnetic radiation

Answer 15

Radiation that is made up of perpendicular electrical and magnetic waves that oscillate as they move through space

Question 16

Field of view

Answer 16

The amount of area that is visible through the microscope’s lens

Question 17

Focus

Answer 17

The point where beams of light converge

Question 18

Fluorescence

Answer 18

Physical property displayed when a substance absorbs light at a shorter wavelength (higher energy) and then emits light at a longer wavelength (lower energy)

Question 19

Fluorescence microscopy

Answer 19

A form of optical microscopy where a sample is irradiated with light that excites molecules in the sample to emit fluorescent light that is then detected

Question 20

Infrared light

Answer 20

The portion of the electromagnetic spectrum with wavelengths longer than visible light and shorter than radio and microwaves in the range of ca. 750 nm to 1 mm.

Question 21

Magnification

Answer 21

Process of making an object appear larger

Question 22

Optical microscopy

Answer 22

• light microscopy.
• Uses visible light to visualize and magnify a small object

Question 23

Phase contrast microscopy

Answer 23

• light microscopy
• uses small differences in the phase shift of the light transmitted or reflected by the sample to form the image

Question 24

Real image

Answer 24

An image produced from an object when the light from the object passes through a single point

Question 25

Resolving power

Answer 25

The ability of an optical system(ie. a microscope) to separate images that are close together

Question 26

Retina

Answer 26

Layer of cells at the back of the eye that converts light energy striking the cells into an electrical impulse that passes into the brain