Bio Midterm Exam Flashcards
(42 cards)
When using 40x objection lense what is the total magnification
400x
What does a spectrophotometer measure?
The absorbance of light
Why do you need to calibrate/zero a spectrophotometer?
To make sure the solvents we are trying to measure are only measured
What substance absorbs wave length
Pigments
What is the equation for %error
What does positive and negative percent error suggest
Equation-measures value-expected value divided by expected value all multiply by 100
Positive-value is higher than expected value
Negative-value is lower than the expected value
How to calculate total magnification
Multiply the power of the objective lens by the power of the ocular lens
What is the purpose of a blank and how do you determine what should be included in it?
A blank is a cuvette contain all other substances except the one you are measuring.
A blanks purpose is to allow the spectrometer to exclude excess substances from the measurement
What type of information does the spectrometer give you
Concentrations of compounds in a solution and determine the magnitude of light absorbed by a sample
What is the difference between abosrbance and transmittance
Absorbance is the extent to which a solution absorbs light
Transmittance is the amount of light that passes through a sample without being absorbed
How does absorbance correspond to the darkness of a solution?
When a solution absorbs more light is appears darker because less light is being transmitting through it
How does the color of light correspond to the wave,night and absorbance?
The color of light is determined by the wavelength. Substances will absorb more light at the specific wavelength that corresponds
What is a standard curve and why do we use it
It’s a plot of known concentrations of a substance against their corresponding absorbance value
It helped us to establish the relationship between the concentration and absorption they produce
What is a dilution factor and why did we use one?
It’s a ratio that describes the amount of solute to the total volume of the solution.
It was used to decrease the concentration of the solution by adding more solvent
What is the Bradford reagent? What does it do in the absence of proteins?and presence of proteins
It’s a reaction used to detect and quantify proteins in a sample.
In the presence the dye binds to them and result in color change from brown to blue
In the absence there won’t be binding and it will remain brown
What does ELODEA look like in a hypertonic and hypotonic solution?
Hypotonic-water flows in the cell and is turgid
Hypertonic–water flows out of the cell and is plasmalazed
What is the equation for % error?
Measure value-expected value
————————————————*100
Expected value
What does a positive and negative percent error mean?
Positive means the experimental value is more than the expected value.
Negative means the experimental value is less than the expected value.
How do you calculate total magnification?
By multiplying the power of the objective lens by the power of the ocular lens which is 10x
How do you use a spectrophotometer?
What is the purpose of the blank?
Blank allows the spectrophotometer to exclude the substances from the measurements.
How do you determine what should be included in the blank cuette?
The coveted should contain all substances except the one you are measuring
Why did you use both sweet and white potatoes for this experiment? Which potato had a higher internal molarity?
Sweet potato and white potatoes have different concentrations of starch ad sugars which would affect osmosis differently.
What was the purpose of the potato experiment?
To observe osmosis in plant cells and to see how water moves in and out of the cells.
What does Elodea look like in an isotonic solution? A hypertonic solution?
Isotonic-it looks normal maintingnits shape and turgid pressure because water concentration is balanced inside and outside the cell.
Hyepertonic- appears shriveled as water is moving out the cell causing it to lose turgor pressure
