BIO 210 LAB MIDTERM EXAM
QUESTIONS AND ANSWERS 100%
CORRECT.
Parfocal - ANSWERThe ability of a microscope to remain in focus when changing from
one objective lens to another with little or no adjustment
Arm - ANSWERConnects base to body tube that contains lenses
Base - ANSWERLight source, on/off switch, voltage regulator (rheostat)
Ocular lens
- binocular - ANSWEREyepieces (10x magnification)
binocular- 2 oculars- adjustable to fit interpupilary distance
Course Adjustment Knob - ANSWERLarge knob on either side of arm that moves stage
up or down slightly to adjust sharpness or specimen focus
Stage - ANSWERPlatform that holds specimen
-mechanical stage knobs: move specimen around
Condenser - ANSWERDirects and condenses rays from light source at base- can be
moved up or down by knob on right side of arm below focus knobs
Diaphragm - ANSWEROpens and shuts condenser aperture to allow more or less light
through condenser to specimen. Knob to operate at front of condenser
Blue filter - ANSWERBlue glass in condenser that provides maximum resolution
Resolution
- resolving power - ANSWERThe ability of a microscope to separate or distinguish
between two small objects that are close together
Nosepiece - ANSWERHouses the objective lenses
Ways to optimize resolution (four) - ANSWER1. raise condenser
2. open diaphragm (iris diaphragm open)
3. use blue filter (condenser up)
4. use immersion oil with 100X objective
, Total Magnification - ANSWERThe product of the magnifying power of the ocular lens
times the magnifying power of the objective lens. ex. 10x ocular lens X 40x objective
lens= 400x
Immersion Oil - ANSWERSpecial type of mineral oil that is only used with 100x
objective lens to enhance focus and resolution because it has the same index of
refraction as glass in the lens thus eliminating distortion cause by loss of light due to the
bending of light rays as the pass through the air. It must interface between the objective
lens and the specimen slide
Proper viewing Procedure - ANSWER1. focus bacteria slide
a. lower power 10x
- start stage up
- light to upper medium (4)
- bring stage down course adj. and fine focus
b. high power 40x blue
- do NOT move stage, objective only
- fine focus
c. oil immersion 100x
- straddle image, do NOT move stage
- touch small oil droplet to stage
- move obj. lens into oil
- fine focus
Ubiquity - ANSWERThe state or capacity of being everywhere
- bacteria are the most widely distributed organisms in the biosphere and are extremely
diverse
Characteristics of a bacterium - ANSWER- unicellular
- prokaryotic (lack a nucleus and organelles)
- cell is surrounded by cell wall composed of peptidoglycan
Colony - ANSWERA viable mass of cells usually resulting from the division of a single
cell
- solid media
Turbidity - ANSWERCloudiness or haziness of a fluid
- broth/liquid media
Characteristics of fungi (4) - ANSWER1. eukaryotic (membrane bound nucleus and
organelles)
2. no tissue
3. non-photosynthetic (no chloroplasts, cannot generate energy from light)
4. cell wall polysaccharides - chitin (a polymer of the carbohydrate N acetyl-
glucosamine)
QUESTIONS AND ANSWERS 100%
CORRECT.
Parfocal - ANSWERThe ability of a microscope to remain in focus when changing from
one objective lens to another with little or no adjustment
Arm - ANSWERConnects base to body tube that contains lenses
Base - ANSWERLight source, on/off switch, voltage regulator (rheostat)
Ocular lens
- binocular - ANSWEREyepieces (10x magnification)
binocular- 2 oculars- adjustable to fit interpupilary distance
Course Adjustment Knob - ANSWERLarge knob on either side of arm that moves stage
up or down slightly to adjust sharpness or specimen focus
Stage - ANSWERPlatform that holds specimen
-mechanical stage knobs: move specimen around
Condenser - ANSWERDirects and condenses rays from light source at base- can be
moved up or down by knob on right side of arm below focus knobs
Diaphragm - ANSWEROpens and shuts condenser aperture to allow more or less light
through condenser to specimen. Knob to operate at front of condenser
Blue filter - ANSWERBlue glass in condenser that provides maximum resolution
Resolution
- resolving power - ANSWERThe ability of a microscope to separate or distinguish
between two small objects that are close together
Nosepiece - ANSWERHouses the objective lenses
Ways to optimize resolution (four) - ANSWER1. raise condenser
2. open diaphragm (iris diaphragm open)
3. use blue filter (condenser up)
4. use immersion oil with 100X objective
, Total Magnification - ANSWERThe product of the magnifying power of the ocular lens
times the magnifying power of the objective lens. ex. 10x ocular lens X 40x objective
lens= 400x
Immersion Oil - ANSWERSpecial type of mineral oil that is only used with 100x
objective lens to enhance focus and resolution because it has the same index of
refraction as glass in the lens thus eliminating distortion cause by loss of light due to the
bending of light rays as the pass through the air. It must interface between the objective
lens and the specimen slide
Proper viewing Procedure - ANSWER1. focus bacteria slide
a. lower power 10x
- start stage up
- light to upper medium (4)
- bring stage down course adj. and fine focus
b. high power 40x blue
- do NOT move stage, objective only
- fine focus
c. oil immersion 100x
- straddle image, do NOT move stage
- touch small oil droplet to stage
- move obj. lens into oil
- fine focus
Ubiquity - ANSWERThe state or capacity of being everywhere
- bacteria are the most widely distributed organisms in the biosphere and are extremely
diverse
Characteristics of a bacterium - ANSWER- unicellular
- prokaryotic (lack a nucleus and organelles)
- cell is surrounded by cell wall composed of peptidoglycan
Colony - ANSWERA viable mass of cells usually resulting from the division of a single
cell
- solid media
Turbidity - ANSWERCloudiness or haziness of a fluid
- broth/liquid media
Characteristics of fungi (4) - ANSWER1. eukaryotic (membrane bound nucleus and
organelles)
2. no tissue
3. non-photosynthetic (no chloroplasts, cannot generate energy from light)
4. cell wall polysaccharides - chitin (a polymer of the carbohydrate N acetyl-
glucosamine)
