Simple Stain: What colour are unstained bacterial cells under a microscope correct answers Transparent
Simple Stain: Why is it called a simple stain (reference colouring of the cells) correct answers All the cells get stained the same colour
Simple Stain: What do we learn about the cells? cor...
BIOL 240 Lab Exam || 100% ACCURATE ANSWERS.
Simple Stain: What colour are unstained bacterial cells under a microscope correct answers
Transparent
Simple Stain: Why is it called a simple stain (reference colouring of the cells) correct answers
All the cells get stained the same colour
Simple Stain: What do we learn about the cells? correct answers Cell morphology (size and
shape)
Simple Stain: Give some examples of dyes used correct answers Methylene blue, crystal
violet, red fuschin
Simple Stain: There are 2 main types of simple stains, what are they? correct answers
Positive and Negative
Simple Stain: In a positive stain, the stain is __________ correct answers alkaline (basic)
Simple Stain: What gives the dye colour? correct answers The chromophore
Simple Stain: the chromophore is ________ correct answers cationic (positively charged)
Simple Stain: What was the name of the dye we used? correct answers Methylene blue
(chloride)
Say we stained Se, Bs, and Ec with Methylene blue
What colour(s) would they stain? correct answers All of the stains would be coloured blue
What is the purpose of flaming the mouth of the test tube? correct answers Prevent cooler,
contaminated air from getting into the test tube and to sterilize the mouth of the tube
How does heat fixing work? correct answers Coagulates the bacterial proteins and adheres
them to the surface of the slide
What would happen if we didn't heat-fix? correct answers Flooding the slide with dye and
washing it would just wash away the smear
What would happen in we heat fixed too much? correct answers The proteins would denature
and the bacterial cells would be deformed.
Microscope Operation: 3 main parts correct answers Lens system, Gears for adjustment,
Light source
Microscope Operation: What magnifies the image? (2 parts) correct answers The objective
lens and the ocular lens
Microscope Operation: What parts should we use to carry a microscope correct answers The
arm and the base
, Microscope Operation: How do we store a microscope correct answers Stage all the way up,
The 4X objective lens, cord wrapped
Microscope Operation: What is the purpose of the stage? correct answers To move the slide
up, down, left, right to observe the smear
Microscope Operation: what is the nosepiece correct answers The part of the microscope
containing the objective lenses
Microscope Operation: How do you calculate total magnification? correct answers ocular
lens x objective lens
Microscope Operation: What is the relationship between the iris diaphragm and the condenser
correct answers The iris diaphragm controls the amount of light that passes through the
condenser
Microscope Operation: what happens when too much light is passed through the slide?
correct answers Contrast decreases
Microscope Operation: How to maximize capture of your image? (lens and light settings)
correct answers match lens magnification to light setting like 100X for BOTH (put light all
the way)
Microscope Operation: What are names of knobs we use to focus the image on the slide?
correct answers FINE and COARSE adjustment knobs
Microscope Operation: Instead of rotating lenses on the nosepiece by the lens, what should
we use? correct answers Rotate by knurled ring
Microscopic Operation: What is the Basic Rule of Focus? correct answers Focus AWAY
from your slide/specimen
Microscope Operation: Why do we use oil on 100x objective lens? correct answers
Focus/Improve the passage of light through the objective lens
Basic Bacterial Shapes: what causes morphology to change when working with bacteria
correct answers age and pH of the culture - acidic and older cultures tend to exhibit gram-
variable stains
Basic Bacterial Shapes: how to calculate the magnification of the image correct answers
ocular mag (10X) by objective mg (variable)
Micropipettes: What two levers do we push on? correct answers tip ejector and volume
plunger
Micropipettes: When taking in solution, how far should you press the stop? correct answers
to the FIRST stop
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