# AP Biology Lab Review

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```							      AP Biology Lab Review
Fred and Theresa Holtzclaw
Webb School of Knoxville

Using Figures from The LabBench
by Theresa Knapp Holtzclaw

Modified from work by Kim Foglia

AP Biology                                          2007-2008
Lab 1: Diffusion & Osmosis
Factors that affect diffusion across the membrane

AP Biology
Lab 1: Diffusion & Osmosis
 Description
   dialysis tubing filled with starch-
glucose solution in beaker filled with
IKI solution

   dialysis bags in
different molarities

   potato cores in
sucrose solutions
AP Biology
Lab 1: Diffusion & Osmosis
 Concepts
 semi-permeable membrane
 diffusion

 osmosis

 solutions

 hypotonic
 hypertonic
 isotonic
   water potential

AP Biology
Lab 1: Diffusion & Osmosis
 Conclusions
 water moves from high concentration of
water (hypotonic=low solute) to low
concentration of water (hypertonic=high
solute)
 solute concentration &
size of molecule
affect movement
through
semi-permeable
membrane
AP Biology
Water potential and water movement
Know how water potential is measured and relationship to solute concentration
and pressure potential

 water moves                                      What are the 2
from a region of                                   components of
high water                                         water potential?
potential to a
region of low
water potential

AP Biology
Calculating Water Potential
Water potential is calculated using the following
formula:

Water potential ( ) = pressure potential ( ) + solute
potential( )

Pure water at atmospheric pressure has a solute
potential of zero.

As solute is added, the value for solute potential
becomes more ________ and water potential
_____.

AP Biology
Know the relationship of molarity to osmotic concentration

AP Biology
1. In beaker B, what is the water potential of the distilled water in
the beaker, and of the beet core?

a. Water potential in the beaker = 0, water potential in the beet
core = 0
b. Water potential in the beaker = 0, water potential in the beet
core = -0.2
c. Water potential in the beaker = 0, water potential in the beet
core = 0.2
d. Water potential in the beaker cannot be calculated, water
potential in the beet core = 0.2
e. Water potential in the beaker cannot be calculated, water
potential in the beet core = -0.2
AP Biology
2. Which of the following statements is true for the diagrams?

a.The beet core in beaker A is at equilibrium with the surrounding
water.

b.The beet core in beaker B will lose water to the surrounding
environment.

c.The beet core in beaker B would be more turgid than the beet core
in beaker A.

d.The beet core in beaker A is likely to gain so much water that its
cells will rupture.

e.The cells in beet core B are likely to undergo plasmolysis.

AP Biology
Lab 1: Diffusion & Osmosis
ESSAY 1992
A laboratory assistant prepared solutions of 0.8 M, 0.6 M, 0.4 M, and
0.2 M sucrose, but forgot to label them. After realizing the error, the
assistant randomly labeled the flasks containing these four unknown
Design an experiment, based on the principles of diffusion and osmosis,
that the assistant could use to determine which of the flasks contains
each of the four unknown solutions.
a. a description of how you would set up and perform the experiment;
b. the results you would expect from your experiment; and
c. an explanation of those results based on the principles involved.

AP Biology
Lab 2: Enzyme Catalysis
What factors affect the rate of an enzyme reaction?

 Description
   measured factors affecting enzyme
activity
H2O2  H2O + O2
catalase


 measured rate of O2 production

Name an enzyme, substrate, products

AP Biology
AP Biology
Lab 2: Enzyme Catalysis
How can the structure of an enzyme be altered?
 Concepts
 substrate
 enzyme
 enzyme structure
 product
 denaturation of protein

 experimental design
 rate of reactivity
 reaction with enzyme vs. reaction without
enzyme
 optimum pH or temperature
 test at various pH or temperature values
AP Biology
Lab 2: Enzyme Catalysis
Be able to calculate the rate of a reax

AP Biology
Lab 2: Enzyme Catalysis
 Conclusions
   enzyme reaction rate is affected by:
 pH
 temperature
 substrate concentration
 enzyme concentration
calculate rate?

AP Biology
Lab 2: Enzyme Catalysis
1. In order to keep the rate of reaction constant over
the entire time course, which of the following should
be done?

b. Gradually increase the temperature after 60 seconds

d. Add H2SO4 after 60 seconds.

e. Remove the accumulating product
AP Biology
Lab 2: Enzyme Catalysis
2. What is the role of sulfuric acid (H2SO4) in this
experiment?

a.It is the substrate on which catalase acts.

b.It binds with the remaining hydrogen peroxide during
titration.

c.It accelerates the reaction between enzyme and substrate

d.It blocks the active site of the enzyme.

e.It denatures the enzyme by altering the active site.

AP Biology
Lab 2: Enzyme Catalysis
3. A student was performing a titration for this laboratory,
and accidentally exceeded the endpoint. What would be
the best step to obtain good data for this point?

a.Estimate the amount of KMnO4 that was in excess, and
subtract this from the result.

b.Repeat the titration using the reserved remaining sample.

c.Obtain data for this point from another lab group.

d.Prepare a graph of the data without this point, and then
read the estimated value from the graph.

AP Biology
Lab 2: Enzyme Catalysis
ESSAY 2000
The effects of pH and temperature were studied for an enzyme-catalyzed
reaction. The following results were obtained.

a. How do (1) temperature and (2) pH affect the activity of this enzyme? In
structure and the function of this enzyme, as well as a discussion of ho
structure and function of enzymes are affected by temperature and pH.
b. Describe a controlled experiment that could have produced the data
shown for either temperature or pH. Be sure to state the hypothesis that
was tested here.

AP Biology
Lab 3: Mitosis
 Description
   cell stages of mitosis
 exam slide of onion root tip
 count number of cells in each stage to
determine relative time spent in each stage

AP Biology
Lab 3: Mitosis
 Concepts
    mitosis
   interphase
   prophase
   metaphase             I    P   M   A   T
   anaphase
   telophase

 Conclusions
    Mitosis
 cell division
 growth, repair
 making clones
 longest phase = interphase
 each subsequent phase is
shorter in duration
AP Biology
The cell cycle

10-12 hours
5-6 hours

4-5 hours
Know these:

Mitosis
Cytokinesis
AP Biology
Cell Cycle
Cytokinesis in animal cells

Compare and contrast plant
and animal cytokinesis

AP Biology
Lab 3: Mitosis
Know the events of mitosis and meiosis in plant and animal cells

AP Biology
Lab 3: Mitosis

AP Biology
Lab 3: Mitosis

AP Biology
AP Biology
Lab 3: Mitosis

AP Biology
Lab 3: Mitosis

AP Biology
Mitosis in a plant cell

Lab 3: Mitosis

AP Biology
Mitosis in an onion root
Know how to calculate the relative duration of each stage

AP Biology
Lab 3: Mitosis
The cell cycle in a certain cell type has a duration
of 10 hours. The nuclei of 660 cells showed 33
cells in anaphase. What is the approximate
duration of anaphase in these cells?

a.2 minutes
b.10 minutes
c.20 minutes
d.30 minutes
e.600 minutes

AP Biology
Lab 3: Meiosis
 Stages
 Importance of Crossing Over

 farther genes are from each other, the greater
number of crossovers

AP Biology
Lab 3: Mitosis & Meiosis
    meiosis
 meiosis 1
 meiosis 2
    crossing over
 Synapsis

AP Biology
Meiosis I

******
Note that at the end of Meiosis I homologs have separated
AP Biology
Meiosis II

AP BiologyNow,   what is separated in Meiosis II?
Meiosis

1. How many times is the DNA replicated?
2. How many divisions?
3. When is chromosome # reduced?
AP Biology
INDEPENDENT ASSORTMENT INTRODUCES VARIABILITY

AP Biology
CROSSING OVER INTRODUCES VARIABILITY

AP Biology
Points of Variability
1. Independent assortment
How many different combinations of
male/female chromosomes are possible in
humans?

2. Crossing over

3. Random fertilization

and all of this variation is without mutation . . .

AP Biology
AP Biology
Lab 3: Meiosis in Sordaria
   Meiosis
 4:4 arrangement in
ascospores
 no crossover
 any other arrangement
 crossover
 2:2:2:2 or 2:4:2

AP Biology
Sordaria analysis
total crossover
% crossover =
total offspring

distance from      % crossover
=
centromere             2

AP Biology
Sordaria analysis

AP Biology
A group of asci formed from crossing light-spored Sordaria
with dark-spored produced the following results:

Number of Asci Counted              Spore Arrangement
7                           4 light/4 dark spores
8                           4 dark/4 light spores
3                           2 light/2 dark/2 light/2 dark spores
4                           2 dark/2 light/2 dark/2 light spores
1                           2 dark/4 light/2 dark spores
2                           2 light/4 dark/2 light spores

How many of these asci contain a spore arrangement that
resulted from crossing over?
a.3    b.7     c.8   d.10 e.15

AP Biology
Lab 3: Mitosis & Meiosis
ESSAY 1987
Discuss the process of cell division in animals. Include a description of
mitosis and cytokinesis, and of the other phases of the cell cycle. Do not
include meiosis.

ESSAY 2004
Meiosis reduces chromosome number and rearranges genetic
information.
a. Explain how the reduction and rearrangement are accomplished in
meiosis.
b. Several human disorders occur as a result of defects in the meiotic
process. Identify ONE such chromosomal abnormality; what effects does
it have on the phenotype of people with the disorder? Describe how this
abnormality could result from a defect in meiosis.
c. Production of offspring by parthenogenesis or cloning bypasses the
typical meiotic process. Describe either parthenogenesis or cloning and
compare the genomes of the offspring with those of the parents.
AP Biology
http://apcentral.collegeboard.co
m/apc/members/repository/ap04
_sg_biology_37082.pdf

AP Biology                          2007-2008
Lab 4: Photosynthesis

AP Biology
Lab 4: Photosynthesis
 Description
     determine rate of photosynthesis under
different conditions
 light vs. dark
 boiled vs. unboiled chloroplasts
 chloroplasts vs. no chloroplasts
     use DPIP in place of NADP+
 DPIPox = blue
 DPIPred = clear
     measure light transmittance
     paper chromatography to
separate plant pigments
AP Biology
Lab 4: Photosynthesis
 Concepts
 photosynthesis
 Photosystem 1
   chlorophylls & other
plant pigments
   chlorophyll a
   chlorophyll b
   xanthophylls
   carotenoids
   experimental design
 control vs. experimental
AP Biology
Lab 4: Photosynthesis
 Conclusions
   Pigments
 pigments move at different rates based on
solubility in solvent
   Photosynthesis
 light & unboiled
chloroplasts
produced
highest rate of
photosynthesis

Which would be the control?           DPIP + no chloroplasts
AP Biology
Lab 4: Photosynthesis
What is the Rf for chlorophyll a?

AP Biology
Lab 4: Photosynthesis
1. Which graph would be the most likely result of performing the
photosynthesis experiment using fresh chloroplasts placed in
light and DPIP?

2. What is the best explanation for graph B?
a.The DPIP was too pale at the beginning of the experiment.
b.The chloroplast solution was too concentrated.
c.The experimenter used chloroplasts that were damaged and
could not respond to light.
d.The blank was not properly used to calibrate the
spectrophotometer.

AP Biology
Lab 4: Photosynthesis
3. What effect would adding more DPIP to each experimental
tube have on these results?
a.Each curve would be shifted downward but would keep the
same general shape.
b.The curve in graph C would rise more steeply and level off
sooner.
c.The curve in graph A would have the same general shape as
the curve in graph C.
d.The chloroplasts would absorb more light energy, so there
would be no change.

AP Biology
Lab 4: Photosynthesis
4. What is the role of DPIP in this experiment?
a.It mimics the action of chlorophyll by absorbing light
energy.
b.It serves as an electron donor and blocks the formation of
c.It is an electron acceptor and is reduced by electrons from
chlorophyll.
d.It is bleached in the presence of light, and can be used to
measure light levels.

AP Biology
Lab 4: Photosynthesis
5. Some students were not able to get many data points in this
experiment because the solution went from blue to colorless in
only 5 minutes for the unboiled chloroplasts exposed to light.
What modification to the experiment do you think would be
most likely to provide better results?

a.Increase the number of drops of chloroplasts used from 3 to 5.

b.Double the volume of DPIP so that the solution has a lower
initial transmittance.

c.Modify the blank so that the initial transmittance is higher.

d.Use fresher spinach and prepare the chloroplast solution
during the laboratory procedure.

e.Change the wavelength at which data is collected

AP Biology
Lab 4: Photosynthesis
ESSAY 2004 (part 1)
A controlled experiment was conducted to analyze the effects of darkness and
boiling on the photosynthetic rate of incubated chloroplast suspensions. The dye
reduction technique was used. Each chloroplast suspension was mixed with
DPIP, an electron acceptor that changes from blue to clear when it is reduced.
Each sample was placed individually in a spectrophotometer and the percent
transmittance was recorded. The three samples used were prepared as follows.
Sample 1 — chloroplast suspension + DPIP
Sample 2 — chloroplast suspension surrounded by foil wrap to provide a
dark environment + DPIP
Sample 3 — chloroplast suspension that has been boiled + DPIP

Data are given in the table on the next page.
a. Construct and label a graph showing the results for the three samples.
b. Identify and explain the control or controls for this experiment.
c. The differences in the curves of the graphed data indicate that there were
differences in the number of electrons produced in the three samples during
the experiment. Discuss how electrons are generated in photosynthesis and
why
AP Biology the three samples gave different transmittance results.
Lab 4: Photosynthesis
ESSAY 2004 (part 2)

Time    Light, Unboiled Dark, Unboiled     Light, Boiled
(min)   % transmittance % transmittance   % transmittance
Sample 1        Sample 2          Sample 3
0           28.8            29.2              28.8

5           48.7            30.1              29.2

10          57.8            31.2              29.4

15          62.5            32.4              28.7

20          66.7            31.8              28.5

AP Biology

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