lab 1 using your microscope

Question 1

compound bright field microscope

Answer 1

• two sets of lenses to help magnify the specimen
• oculars
• objectives
• bright-field means specimen will appear on a light background
• often need to stain in order to view them using bright field illumination

Question 2

phase contrast microscope

Answer 2

• contains a special condenser to increase the contrast bw a specimen and the background
• allows you to observe live unstained specimens and is particularly useful for observing motel organisms and endospores

Question 3

electron microscopes

Answer 3

• used to examine cells and viruses at very high magnifications
• an electron beam has a much shorter wavelength than visible light, and this allows for a much higher resolution
• over 100,000X magnification

Question 4

magnification

Answer 4

degree to which the size of an image is larger than the image itself

Question 5

resolution

Answer 5

degree to which it is possible to distinguish bw 2 objects that are very close

Question 6

oculars

Answer 6

• 10X

- binocular -has 2 oculars

Question 7

objectives

Answer 7

3 objectives attached to a nosepiece
10X, 40X, 100X
-used to magnify your specimen
-100X has black ring around it and needs immersion oil
-40X and 100X are par-focal

Question 8

parfocal

Answer 8

the objectives have been configued to have the same focal point as each other

Question 9

condenser

Answer 9

• controls the amount of light passing through your specimen
• focuses the light into a concentrated beam
• moves up and down
• should be as close to the stage as possible for best illumination

Question 10

iris diaphragm

Answer 10

• slides left to right
• to increase contrast close diaphragm
• to observe colours, open diaphragm, more light
• controls the beam of light passing through the condenser

Question 11

how do you define the term microorganism

Answer 11

most microorganisms have limited differentiation

Question 12

total magnification

Answer 12

ocular magnification X objective magnification = total magnification

Question 13

when you want to see any coloured specimen

Answer 13

the iris diaphragm should be in the fully open position

Question 14

immersion oil

Answer 14

100X objective

• immersion oil has the same refractive index as glass, which makes sure that the light passing through the specimen enters the objective and is not refracted away
• prevent the light from bending and thus increase the amount of light that enters into the objective
• more light-better resolution
• connecting your lens to your specimen with liquid glass

Question 15

bacteria- prokaryote

Answer 15

mixed true bacteria,

anabaena

Question 16

eukaryotes

Answer 16

euglena
saccharomyces
penicillium

Question 17

prokaryotes

Answer 17

micrococcus luteus
anabaena
staphylococcus epidermis

Question 18

prokaryotes are

Answer 18

unicellular
no membrane bound organelles 
mostly roads and cocci
bacteria - wide range of habitat
bacteria- form the largest and most diverse group of prokaryotes

Question 19

cyanobacteria

Answer 19

• largest photosynthetic bacteria
• ability to fix N gas
• important in producing the oxygen we breath
• many form symbiotic relationships with other organisms
• anabaena forms a mutualistic symbiosis with a water fern (azolla)
• cyanobacteria lives inside the leaves of the azolla and converts atmospheric N into a usable form for the plant
• akinetes- resting structures that protect the organisms during periods of drought or freezing( large, oval)
• heterocyst- thick walled N fixing cells (small, clear)

Question 20

euglena

Answer 20

• protist
• can be both heterotrophic or photosynthetic
• some motile some not
• most unicellular but some multicellular
• flagellum
• algae and protozoa
• quite motile

Question 21

fungi

Answer 21

heterotrophic

• obtain their nutrition through osmotrophy
• important decomposers
• filamentous molds
• unicellular yeast

Question 22

filamentous molds

Answer 22

form of a fungus

penicillium

Question 23

unicellular yeast

Answer 23

reproduce by budding

Saccharomyces cerevisiae

Question 24

to view saccharomyces cerevisiae and penicillium..

Answer 24

the iris diaphragm must be closed bc they are colourless

Question 25

petri plates are incubated

Answer 25

upside down so it prevents condensation on the lid from running onto the agar surface
incubated at 28 degrees C

Question 26

each colony on a petri plate…

Answer 26

arose from a single cell or spore
-when nutrients are plentiful, a cell deposited on the surface of an agar plate will start to divide
soon millions of cells will exist on the spot where that first cell was deposited
-mass of cells is called a colony
-characteristics associated with that colony are also characteristic of individual cells

Question 27

fungal colonies

Answer 27

grow by elongating their long filamentous hyphae, rather than dividing
-mass of hyphae, called mycelia is also called colony because it arose from a single spore deposited on the plate
-grow much larger than bacteria and may take over your entire plate
-contaminated
fuzzy and grey or black and large and has white ring around it

Question 28

B. su

Answer 28

wrinkles
flat
undulate
white 
opaque
dull

Question 29

refractive index

Answer 29

is a measure of the way light travels through a medium

Question 30

MOST of the organisms we deal with are

Answer 30

invisible to the naked eye