BIOL 107 LAB EXAM QUESTIONS AND
ANSWERS
What is a pure culture? - Correct Answers -A pure culture is an isolated group of
genetically identical cells. (also known as colony).
unit conversions: - Correct Answers -1m= 100cm= 1000mm= 1E6μm= 1E9nm
What are the three lenses in a light microscope? - Correct Answers -1) condenser lens-
focuses the light from underneath onto the specimen.
2) objective lens- magnifies the image.
3) occular lens (eyepiece) - magnifies the image and inverts it.
Light Microscope (bright field) terminology - Correct Answers -Diaphragm- controls the
amount of light entering the lens system. Less light can improve contrast (the difference
between light and dark areas).
Stage.
The total magnification of the microscope is equal to...? - Correct Answers -The product
of the ocular lens (usually 10X) and the objective lens.
What is resolution? - Correct Answers -The capacity to distinguish between two
adjacent points. Eg) if resolution= 3μm, we are capable of distinguishing two objects
that are 3μm or more apart as being two different objects.
What is a hypotonic solution? - Correct Answers -One where the solute concentration is
higher inside the cell, the cell will fill with water and become turgid.
What is a hypertonic solution? - Correct Answers -One where the solute concentration
is higher outside the cell, so the cell will lose its water and become plasmolyzed.
The steps involved in the scientific method: - Correct Answers -1) formulate an idea or
question.
2) Formulate a hypothesis (educated guess) that is based on prior knowledge.
3) Test the hypothesis- this can be done by observation or experimentation, or both.
The independent variable is the one that is manipulated, the dependent variable is the
one being measured.
4) draw a conclusion based on the results. Say "supports", not "proves".
* A theory is a very well proven and accepted hypothesis.
, What is flaccid? - Correct Answers -Cell than is neither turgid nor plasmolyzed, this
occurs in isotonic cells.
What is the tonoplast (beta vulgaris)? - Correct Answers -The tonoplast is the
membrane surrounding the central vacuole that contains the betacyanin. The
betacyanin must also pass throught the plasma membrane.
What is absorbance and turbidity? - Correct Answers -Absorbance is when particles
absorb light.
Turbidity is when particles scatter light.
Betacyanin.... - Correct Answers -Maximally absorbs light at 525nm so this is what we
set the spec to.
What is transmittance (T) - Correct Answers -Transmittance refers to the ratio of
transmitted light (light leaving the sample) to incident light (light striking the sample),
therefore it is expressed as a percentage.
What is optical density? - Correct Answers -OD refers to the measurement of light that
gets absorbed or scattered (not transmitted).
What is absorbance? - Correct Answers -It is simply the negative log of transmittance.
How is the standard curve used to help us calculate concentrations? - Correct Answers
-We use a stock solution of betacyanin and dilute it to different concentrations. Then we
create a standard curve where absorbance is linearly proportional to concentration.
Then we can compare the leakage in beta vulgaris to this standard curve to find the
unknown concentrations.
*standard curve CANNOT be extrapolated.
What is the concentration for dilution? - Correct Answers -Dilution= V of original
solution/ V of original solution + V of solvent.
Example: 0.5 mL of original solution in 4.5 mL of solvent = 1 in 10 dilution (or 0.1).
What is the equation for converting concentration of diluted sample (obtained from the
standard curve), into the undiluted concentration? - Correct Answers -Cu= Cd / D
If bacteria are sensitive to a specific antibiotic then there will be a _____ of ______ on
the agar plate - Correct Answers -zone of inhibition.
What do antibiotics do? - Correct Answers -Prevent the growth of bacteria and or
fungus. They do this in different ways- some block cell wall formation, some block
protein synthesis etc.
ANSWERS
What is a pure culture? - Correct Answers -A pure culture is an isolated group of
genetically identical cells. (also known as colony).
unit conversions: - Correct Answers -1m= 100cm= 1000mm= 1E6μm= 1E9nm
What are the three lenses in a light microscope? - Correct Answers -1) condenser lens-
focuses the light from underneath onto the specimen.
2) objective lens- magnifies the image.
3) occular lens (eyepiece) - magnifies the image and inverts it.
Light Microscope (bright field) terminology - Correct Answers -Diaphragm- controls the
amount of light entering the lens system. Less light can improve contrast (the difference
between light and dark areas).
Stage.
The total magnification of the microscope is equal to...? - Correct Answers -The product
of the ocular lens (usually 10X) and the objective lens.
What is resolution? - Correct Answers -The capacity to distinguish between two
adjacent points. Eg) if resolution= 3μm, we are capable of distinguishing two objects
that are 3μm or more apart as being two different objects.
What is a hypotonic solution? - Correct Answers -One where the solute concentration is
higher inside the cell, the cell will fill with water and become turgid.
What is a hypertonic solution? - Correct Answers -One where the solute concentration
is higher outside the cell, so the cell will lose its water and become plasmolyzed.
The steps involved in the scientific method: - Correct Answers -1) formulate an idea or
question.
2) Formulate a hypothesis (educated guess) that is based on prior knowledge.
3) Test the hypothesis- this can be done by observation or experimentation, or both.
The independent variable is the one that is manipulated, the dependent variable is the
one being measured.
4) draw a conclusion based on the results. Say "supports", not "proves".
* A theory is a very well proven and accepted hypothesis.
, What is flaccid? - Correct Answers -Cell than is neither turgid nor plasmolyzed, this
occurs in isotonic cells.
What is the tonoplast (beta vulgaris)? - Correct Answers -The tonoplast is the
membrane surrounding the central vacuole that contains the betacyanin. The
betacyanin must also pass throught the plasma membrane.
What is absorbance and turbidity? - Correct Answers -Absorbance is when particles
absorb light.
Turbidity is when particles scatter light.
Betacyanin.... - Correct Answers -Maximally absorbs light at 525nm so this is what we
set the spec to.
What is transmittance (T) - Correct Answers -Transmittance refers to the ratio of
transmitted light (light leaving the sample) to incident light (light striking the sample),
therefore it is expressed as a percentage.
What is optical density? - Correct Answers -OD refers to the measurement of light that
gets absorbed or scattered (not transmitted).
What is absorbance? - Correct Answers -It is simply the negative log of transmittance.
How is the standard curve used to help us calculate concentrations? - Correct Answers
-We use a stock solution of betacyanin and dilute it to different concentrations. Then we
create a standard curve where absorbance is linearly proportional to concentration.
Then we can compare the leakage in beta vulgaris to this standard curve to find the
unknown concentrations.
*standard curve CANNOT be extrapolated.
What is the concentration for dilution? - Correct Answers -Dilution= V of original
solution/ V of original solution + V of solvent.
Example: 0.5 mL of original solution in 4.5 mL of solvent = 1 in 10 dilution (or 0.1).
What is the equation for converting concentration of diluted sample (obtained from the
standard curve), into the undiluted concentration? - Correct Answers -Cu= Cd / D
If bacteria are sensitive to a specific antibiotic then there will be a _____ of ______ on
the agar plate - Correct Answers -zone of inhibition.
What do antibiotics do? - Correct Answers -Prevent the growth of bacteria and or
fungus. They do this in different ways- some block cell wall formation, some block
protein synthesis etc.
