Transcript AP Lab 1 - Humble ISD

AP EXAM REVIEW SESSION III
Be prepared, not scared! 
• Experimental Design
• 12 AP Labs
EXPERIMENTAL DESIGN
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Clearly state a hypothesis using the “If…,then” format.
Set up a control group and indicate its purpose.
Use a large sample size.
Identify the independent & dependent variables.
Indicate which variables you will hold constant.
Indicate how you will manipulate the variable you will test; in other words, how will you
conduct your experiment?
Describe how the function you are testing is affected by the change in the variable; in
other words, how is the dependent variable changing in response to the independent
variable?
Describe how you will measure the change in the variable . . . titration, measuring temp
every 2 minutes, etc
Describe how you will verify your experiment (repeat the experiment many times).
Describe how you will analyze your data (run a Chi square test, graph the data)
Relate possible results to the hypothesis; in other words, what results support or reject
your hypothesis?
The AP Labs . . . A Walk Down
Memory Lane 
AP Lab 1 – Diffusion & Osmosis
• Cell Transport
• Tonicity
• Movement of water determined by water potential
 Ψ = ΨS + ΨP
AP Lab 1 – Diffusion & Osmosis, cont
 Part A
 Diffusion across a semipermeable membrane
 Set-up = glucose + starch in dialysis tubing; iodine in beaker
 Part B
 Determined % change in mass of known molarities of sucrose solutions
(dH2O, 0.2 M → 1.0M) placed in distilled water
 Increase or decrease in mass of bags following incubation?
AP Lab 1 – Diffusion & Osmosis, cont
 Part C
 Set up potato cubes in different molarities of sucrose, then calculated,
graphed % change in mass
 Some gained mass, some lost mass
 Molarity of potato = ??
 Part D
 Plasmolysis
AP Lab 2 – Enzyme Catalysis
AP Lab 2 – Enzyme Catalysis, cont
• Purpose: To develop a better understanding of enzyme function by working
with the enzyme catalase
• Reaction:
• KMnO4 used for titration – deep purple color. If H2O2 is present, it reacts with
KMnO4 to form clear product – provides way to measure H2O2
• Procedure
 Determined actual concentration of H2O2 in 1.5% solution of H2O2
 Determined the 24-hour uncatalyzed reaction rate by performing a titration
on the hydrogen peroxide left sitting overnight without the addition of
catalase.
 Catalase was allowed to react with H2O2 for varying amounts of time.
H2SO4 was added to stop the reaction, then amount of H2O2 remaining
was titrated using KMnO4. Data was graphed and reaction rate was
calculated to determine the effect of time on reaction rate.
AP Lab 3 – Mitosis & Meiosis
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Purpose: To observe stages of cell cycle in apical meristem tissue of root tip.
AP Lab 3 – Mitosis & Meiosis, cont
AP Lab 3 – Mitosis & Meiosis, cont
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To observe crossing over in asci of Sordaria by looking at the pattern & colors of
ascospores
AP Lab 4 – Plant Pigments & Photosynthesis
AP Lab 4 – Plant Pigments & Photosynthesis
 Part A
 Purpose: To separate
plant pigments using
chromatography
 Different plant pigments
vary in their affinity for the
chromatography paper
and their solubility in the
solvent, therefore will
travel different distances
along chromatography
paper
AP Lab 4 – Plant Pigments & Photosynthesis
AP Lab 4 – Plant Pigments & Photosynthesis
AP Lab 4 – Plant Pigments & Photosynthesis
 Part B
 Purpose: To measure the rate of photosynthesis in (1) an
unboiled chloroplast solution kept in the dark, (2) an unboiled
chloroplast solution exposed to light, and (3) a solution containing
boiled chloroplasts exposed to light.
 A dye reduction technique was used.
 DPIP acts as electron acceptor. It is normally a blue color but
becomes colorless when it is reduced.
 Color change measured as % transmittance by
spectrophotometer or % absorbance by colorimeter.
 Provides a means to measure electron excitation
AP Lab 5 – Cell Respiration
 Purpose: To
determine the effect of
factors on the rate of
cellular respiration by
measuring oxygen
consumption/carbon
dioxide production by
yeast
AP Lab 5 – Cell Respiration
AP Lab 5 – Cell Respiration
AP Lab 6 – Molecular Genetics
 Part A – Transformation
 First, two suspensions of
bacteria in log phase of
growth were made competent
by heat shock and treatment
with CaCl2
 One tube exposed to plasmid
containing gene for ampicillin
resistance, one tube not
exposed to plasmid
 Each tube is plated on 2 agar
plates, one with ampicillin,
one without, incubated, then
checked for growth
 Expected results?
AP Lab 6 – Molecular Genetics
 Part B – Restriction Enzyme Cleavage
 Identical DNA samples cut with 2 different restriction enzymes
 HindIII fragments measured, base pairs per fragment provided, data
graphed
 EcoRI bands measured, then graph used to interpolate number of base pairs
per fragment
AP Lab 7 – Genetics of Organisms
 Determined phenotypes of P x P
by looking at representative flies
 Analysis of F1 provided information
about cross
 Predictions made for F2
 Null hypothesis:
 F2 offspring counted; results evaluated using Chi square
 Chi-square
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 “Goodness of Fit” Test
 Degrees of freedom =
 If the calculated Chi square value is greater than or equal to the p value
listed for 0.05, null hypothesis is rejected. This means you are 95% certain
that the data does not fit the expected value.
AP Lab 8 – Population Genetics & Evolution
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Purpose: To become familiar with the Hardy-Weinberg equation and to use H-W to
calculate the number of alleles in a population
Five criteria for H-W equilibrium
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Having a widow’s peak is dominant to lacking a widow’s peak. In a population of 920
people, 510 show the dominant phenotype. How many individuals would you expect of
each of the three possible genotypes for this trait?
AP Lab 9 – Transpiration
• Part A
 Transpiration =
 Measured
transpiration rate in
plants exposed to
light, fan,
darkness, and
ambient conditions
AP Lab 9 – Transpiration
• Part B
 Cross section of dicot
stem structure
prepared by using a
microtome to slice
thin sections, staining
them, fixing them to a
slide, and examining
the slide under the
microscope
AP Lab 10 – Physiology of the Circulatory System
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Purpose
 To become familiar with
taking blood pressure
readings,
 To determine the effect of
exercise on pulse rate, and to
determine fitness by
comparing pulse rate when
standing, reclining, after
exercising, and calculating
the amount of time required
for pulse rate to return to
normal after exercise.
 To determine the effect of
temperature on heart rate is
determined using a test
organism.
AP Lab 11 – Animal Behavior
• Purpose: To observe animal behavior and to design an experiment
testing the response of an organism to a stimulus.
 Taxis vs kinesis
AP Lab 12 – Dissolved Oxygen & Aquatic Primary Productivity
• Part A
 Purpose: To determine the relationship between dissolved O2 concentration
and temperature
AP Lab 12 – Dissolved Oxygen & Aquatic Primary
Productivity
• Part B
 Primary productivity = rate of
photosynthesis
 Net productivity = (Primary
productivity) – (Respiration)
 Set up bottles with varying
amounts of light to calculate
effect of light on net productivity
 Measured O2 concentration
using Winkler method
 [dO2 ] fixed
 Iodine concentration
measured by titrating with
sodium thiosulfate, starch
indicator