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Unformatted text preview: AP® Biology
2004 Scoring Guidelines The materials included in these files are intended for noncommercial use by
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For the College Board’s online home for AP professionals, visit AP Central at apcentral.collegeboard.com. AP® BIOLOGY
2004 SCORING GUIDELINES
(a) Explain how the reduction and rearrangement are accomplished in meiosis.
(5 points maximum)
1 point: (homologous) chromosomes pair, then separate
and move to opposite poles during 1st meiotic division
1 point: chromatids separate during 2nd meiotic division
1 point: crossing over (in proper context)
1 point: random alignment (independent assortment) of tetrads
1 point: elaboration (e.g.: correct mechanism/description or
consequences of one of the above) * OR 1 point: two rounds of cell
(nuclear) division but
only one replication of
the chromosomes *NOTE: Diagrams that
are clearly labeled and
are described in the essay
portion are acceptable
and may receive a point (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.
(4 points maximum)
1 point: Identify one condition by name or description
(e.g.: Down or trisomy 21; Turner or XO; fragile X; cri-du-chat or 5p-; etc.)
1 point: Phenotype of the example given above
1 point: Name or identify the meiotic event (e.g.: nondisjunction, unequal crossing over, inversion,
1 point: Description of the meiotic event *
(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.
(3 points maximum)
CLONING OR PARTHENOGENESIS
1 point: Definition
- Parthenogenesis: development of an unfertilized egg into an adult; often the adult is haploid
- Cloning: using a somatic cell or cells from a multicellular organism to make one or more genetically
identical individuals (or inducing a diploid body cell of an organism to revert to its embryonic state
and then develop into a complete adult organism without fertilization)
1 point: Description of an example or the process in a plant or animal (parthenogenesis is rare in plants)
1 point: Comparison of the genomes of offspring and parents (e.g. identical for cloning) Copyright © 2004 by College Entrance Examination Board. All rights reserved.
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2004 SCORING GUIDELINES
(a) For EACH of the four contributions listed below, discuss one example of supporting evidence.
(2 points each; 8 points maximum)
Contributions Possible Examples of Evidence (1 point) The
species ♦ Branching
of all species
in species ♦ Must demonstrate common ancestry
◊ Homology (embryological, structural, molecular,
◊ Vestigial structure from common ancestor
◊ Hominoids, finches, etc…
♦ Must demonstrate change over time (generations)
◊ Vestigial structures (pelvic bones, appendix)
◊ Fossil sequence
◊ Coat color changes
◊ Giraffes’ necks
◊ Antibiotic/pesticide resistance
♦ Must demonstrate an appropriate natural selection
◊ Antibiotics/pesticide resistance
◊ Finches, moths, etc…
◊ Predator/prey relationships Natural selection
as the mechanism
for evolution Explanation/Understanding of Phrase (1 point) Must demonstrate variation
◊ Finches, horses, dogs, whales, peppered
moths, etc.… ♦ Individual variation within a
species/population (can be phenotypic or
♦ Change within species over time (not change in
♦ Change in number of species over time
♦ Shared or common ancestor
♦ Adaptive radiation concept (divergent
evolution, one species becomes 2 or more)
♦ Small changes over time / slow rate of
♦ Genes mutate
♦ Accumulation of genetic/phenotypic changes
♦ Differential reproductive success
♦ Survivors pass genes to next generation
♦ No Lamarckian language (want, need…)
♦ No “survival of fittest” alone Note:
Examples in context may earn 2 points.
Possible examples are not limited to the listings above.
An example alone, without the context of the phrase = no points. Copyright © 2004 by College Entrance Examination Board. All rights reserved.
Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for AP students and parents). 3 AP® BIOLOGY
2004 SCORING GUIDELINES
Question 2 (cont’d.)
(b) Discuss how TWO of the following have modified biologists’ interpretation of Darwin’s original
(3 points each; 6 points maximum)
Definition/Explanation of the
Idea (1 point) Hardy-Weinberg
Equilibrium Description of How It Has
Interpretation of Evolution
* Direct mention of Darwin’s
view is not necessary for
points. ♦ Allele (gene) frequency
remains constant over
time ♦ D - Ongoing gradual
change ♦ Under certain conditions
no evolution occurs Genetic Engineering ♦ Sudden changes in tempo *Hardy-Weinberg
explanation of variables
within equation = no
♦ D - Gradual change ♦ Long period of stasis then
sudden change Punctuated
Equilibrium HW - Constant allele
ratio (must refer to
alleles or genes) PE - Possible rapid
change ♦ Manipulation and/or
alteration of genes/DNA ♦ D - Natural gene transfer
GE - human directed
gene transfer ♦ Others related to
biotechnology ♦ D-Gradual change
GE - rapid change Depth of Discussion /Expansion
Point (1 point)
♦ Discuss evidence
♦ Deeper description of the
♦ Describe applicable
♦ Five conditions of HardyWeinberg Equilibrium cited
correctly (need all 5)
o Very large population
size - no drift
o No movement in or out
of a population
o No net mutations
o Random mating - no
o No natural selection Hardy-Weinberg as a null
hypothesis for determining
cause of change
♦ A graph of punctuated
evolution vs. Darwinian
♦ Discussion of fossil record
reflecting a punctuated
♦ Cloning process expressed
♦ RFLP analysis explained
♦ Universality of genetic code ♦ DNA analysis allows
genomic comparisons Copyright © 2004 by College Entrance Examination Board. All rights reserved.
Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for AP students and parents). 4 AP® BIOLOGY
2004 SCORING GUIDELINES
(a) On the axes provided, construct and label a graph showing the results for the three samples.
(1point each; 3-point maximum)
♦ Orientation of axes is correct: x-axis is time/minutes, y-axis is light transmittance/%
♦ Data are plotted correctly (one misplaced data point is permissible)
♦ Graph is accurate: must include proper scaling and correct labels and units of measurement and key
(b) Identify and explain the control or controls for this experiment.
(1 point each; 3-point maximum)
♦ Sample 1 is the control
♦ Sample 1 is in the light and has permissive temperature/functional structures (membranes, proteins,
♦ Control is the basis for comparison to treatment effects (can award even if wrong sample was identified
as the experimental control)
♦ Reliability of data/design: identical procedures, reagents, measurements, adequate sample size (must
identify at least two)
(b) Discuss how electrons are generated in photosynthesis and why the three samples gave different
(1 point each; 6-point maximum)
♦ Chlorophyll (photosystem, reaction- or photo- center; “chloroplast” alone is not sufficient) is the link
between light (photons) and the generation of electrons
♦ Water is the source of electrons (photolysis, oxidation, splitting)
♦ Electron generation, not simply photosynthesis, is proportional to DPIP reduction light transmittance
♦ Decreasing light availability decreases the quantity of electrons that will be generated, and/or vice versa
♦ Boiling disrupts functional structures (membranes, denaturation of proteins/enzymes, etc.; “chloroplast”
alone is not sufficient)
Elaboration (1 point only)
photosystem II and/or I/Z-scheme
data analysis Copyright © 2004 by College Entrance Examination Board. All rights reserved.
Visit apcentral.collegeboard.com (for AP professionals) and www.collegeboard.com/apstudents (for AP students and parents). 5 AP® BIOLOGY
2004 SCORING GUIDELINES
(a) Identify the participants involved in the symbiosis and describe the symbiotic relationship, and
(b) Discuss the specific benefit or detriment, if any, that each participant receives from the relationship.
1 point maximum is awarded for a correct pair of participants involved in each example given.
Participants must be organisms.
1 point maximum is awarded for describing a correct symbiotic relationship to each example.
1 point maximum is awarded for discussing how each participant is involved in a specific benefit or detriment
from the relationship.
Wrong participants: NO points for participants, relationship, or discussion.
Nonspecific participants: 2 points maximum for relationship and discussion.
1 point maximum for elaborating on any one of the four choices used. 10 points awarded only if 4 choices
Discussion on Each Participant
Plant root nodules Plants/legumes +
Plants receive nitrogen (not N2) while
bacteria receive CHO’s and other
nutrients/water and shelter/hospitable
Host is able to use cellulose as a
microorganisms (bacteria, organisms benefit
nutrient (energy source) while
symbiont gains food/shelter/hospitable
Plants + pathogenic
Host is infected, bacteria/fungi
member is harmed, the receives nutrients
Large trees (plants) +
Host is not affected or given any
member benefits, the
benefit. Symbiont has a substrate for
others are not harmed
anchoring/access to sunlight &
ants/frogs/small animals Mutualism/both
organisms benefit Bromeliads provide water, shelter free
of predation to many insect larva,
frogs, etc…/a source of nitrogen is
given to plant Dodder/mistletoe + plant Parasitism/one
member is harmed, the
is harmed, the other
is harmed, the other
benefits Host has nutrients removed while
epiphyte receives nutrients AIDS Human +
Virus/HIV/retrovirus Anthrax Human/ruminant/
horse/pig + Bacillus
anthracis/bacteria/spores HIV uses host to replicate while
host/immune system is harmed or
Illness or death to host; bacteria
receives nutrients, habitat Copyright © 2004 by College Entrance Examination Board. All rights reserved.
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This note was uploaded on 11/23/2009 for the course BIOLOGY 1101 taught by Professor Keith during the Winter '05 term at The University of Oklahoma.
- Winter '05