LECTURE 2 QUIZ

Question 1

• are used to express the sizes of microbes
• the basic unit length is meter(m) and is equivalent to 39.4 inches
• bacteria and protozoa are usually expressed of ,micrometers (um) (one millionth of a meter)
• typical spherical bacterium is approximately 1 um in diameter
• typical rod shape bacterium is 1 um wide x3 um long

Answer 1

metric system

Question 2

• the sizes of viruses are expressed in terms of nanometers (equal to one billionth of a meter)
• most of the viruses that cause human diseases range in size from 10-300 nm (ex; ebola virus)
• when using microscope, sizes of microorganisms are measured in OCULAR MICROMETER

Answer 2

nanometer (nm)

Question 3

is an optical instrument that is used to observe tiny objects, objects so small that they cannot be seem with the unaided human eye

Answer 3

microscope

Question 4

each optical instrument has a limit as to what can be seeen using that instrument, this limit is referred to as ___________

Answer 4

resolving power or resolution of the instrument

Question 5

resolving power of the unaided human ehe is approx ___

Answer 5

0.2 mm

Question 6

• contains only ONE MAGNIFYING LENS
• images appear to 3-20 times larger than the objects actual size
• leeuwenhoek has a maximum magnifying power of about x300 (300 times)

Answer 6

simple microscope

Question 7

• contains MORE THAN ONE MAGNIFYING LENS
• because visible lights is the source of illumination, a compound microscope is also referred to as the compound light microscope
• objects 1,000 times (approx 0.2 um about 1,000 times better than unaided human eye)

Answer 7

compound microscope

Question 8

the compound light microscope is sometimes referred to as ________ if the condenser is replaced with what is known as a darkfield condenser, ILLUMINATE objects are seem againts a dark backroumd, the microscope is then called _________

Answer 8

brightfield microscope and darkfield microscope

Question 9

other types of compound microscope

Answer 9

phase contrast and fluorescence microscope

Question 10

• used to observe unstained living microorganisms
• organisms are more easily seen because the light refracted by living cells is diff from the light refracted by surrounding medium

Answer 10

phase contrast

Question 11

• contain build in (UV) light source
• when UV strikes certain dyes and pigments, it emits a longer wavelength light, causing them to glow against dark backround

Answer 11

fluorescence microscope

Question 12

• this enable us to see extremely small microbes such as rabies and smallpox viruses
• living organisms cannot be observed using an electron microscope, the processing procedures kill the microorganisms
• used as the source of illumination, magnets focus on the beam
• have a much HIGHER resolving microscope than compound microscope
  TWO TYPES OF IT ARE (transmission and scanning)

Answer 12

ELECTRON MICROSCOPE

Question 13

• this microscope uses an electron gun to fire a beam of electrons through extremely thin specimen
• an image of the specimen is produced on a phosphor coated screen

Answer 13

transmission electron microscope

Question 14

• electrons are bounced off the surface of a specimen and the image APPEARS on the monitor.
• used to observe outer surfaces of specimen
• resolving power 100 times less than of transmission electron
• trans and ____ electron micrograph are black and white images

Answer 14

scanning electron microscope