Free Response Guide


| 2010 #3 | 2010 #4 | 2010B #4 | 2009 #3 | 2009B #2 | 2008 #4 | 2008B #3 | 2007B #1 | 2007B #4 | 2006 #1 | 2006B #1 | 2005 #3 | 2004 #2 | 2003 #1 | 2003 #3 | 2003B #4

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2010 #3

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(a) Conclusions from cross I and II?
- bronze dominant/ red recessive
- autosomal (non-sex-linked)
- all F1/heterozygotes express dominant trait (bronze)
- F2 shows 3:1 ratio
- equal distribution of F2 phenotypes for both genders

- stunted dominant/ normal recessive
- autosomal (non-sex-linked)
- all F1/heterozygotes express dominant trait (stunted)
- F2 shows 3:1 ratio
- equal distribution of F2 phenotypes for both genders

(b) Conclusions from cross III?
- genes linked
- crossing over
- genes 10 map units apart
- not 1:1:1:1 ratio as predicted by independent assortment
- not 1:1 ratio/two recombinant phenotypes, unexpected
- frequency of recombinant phenotypes was 10%
- parental types 90% of offspring

(c) Identify and discuss 2 factors that affect whether in H-W equilibrium
- large population = minimized genetic drift
- random mating = no gene pool change due to mate preferences
- no mutation = no new alleles in population
- no gene flow/migration = no gene pool change by addition/loss of alleles
- no natural selection = no alleles favored or disfavored by environment


2010 #4

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(a) Discuss expected changes in biodiversity as stages of succession progress
- biodiversity increases
- some pops. facilitate succession by developing conditions more suitable to others species, ex. more fertile soil due to decay of plants
- some pops. inhibit succession
- increase in plant stratification, which changes conditions, ie. canopy, understory
- more niches/habitats formed for plants/animals/decomposers
- pioneer plant species to dominants, more shade-tolerant plants
- increase in producer diversity, more increase in consumer diversity
- shift from r-strategists to K-strategists

(b) Describe/Explain 3 changes in abiotic conditions that lead to succession
- more soil = more detritus, decreased erosion to hold soil = provides more anchoring for plants
- soil quality = more organic matter (humus) = more nutrients
- more N available = decomposition = more plants with high nitrogen needs
- more P = decomposition = more plants with high phosphorus needs
- water retained = organic matter retains water, shading reduces evaporation = more water for plants
- decrease in light/temperature = shading = favors shade tolerant, heat intolerant
- higher humidity = more transpiration = from xerophytic plants to mesophytic

(c) Discuss the immediate/long-term effects of each disturbance
Volcano Erupts:
- primary succession, no soil
- lava degraded by weathering, microbes, lichens, fungi, to form soils
- lots of light, photophilic organisms will thrive when soil present

Mature Forest Clear-Cut:
- secondary succession, soil present
- not all life destroyed
- seed banks present
- different/other habitats/niches open/close
- loss of trees may lead to erosion, soil loss
- lots of light available
- smaller plants may benefit


2010B #4

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(a) Propose 2 abiotic and 1 biotic variable that could explain why millipedes found more frequently under logs
Abiotic:
- light
- temperature
- water
- soil texture, nutrients, pH
- wind
- periodic disturbances, fire/storms/volcanoes

Biotic:
- reproduction
- predation
- food supply
- competition

(b) For 1 abiotic variable above, design a controlled experiment to test whether it affects millipedes on the forest floor
- hypothesis
- prediction/expected results
- design
- constants
- control, serves comparison for experimental groups
- data
- sample size
- statistical analysis
- feasability

(c) Describe modifications to experiment but with a plant, determine whether abiotic factor affects distribution of plant
- describe modifications
- describe control
- explanation, why it would affect plant
- feasibility


2009 #3

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(a) Identify 2 mechanisms of genetic change, explain how each affects genetic variation
DNA (molecular):
- mutation (point, frameshift, insertions, deletions) = change in nucleotide sequence/amino acid sequence/protein structure/gene expression/phenotype
- Duplication, ex. gene, chromosome, genome, sympatric speciation = gene "families" which then diverge by mutation, change in ploidy
- , ex. gene order, inversions, chromosome fusion, transposons = chromosome structure altered, change in crossover frequency

Cellular:
- crossing over, independent assortment, segregation, nondisjunction, random fertilization = increase gamete diversity, many possible gamete combinations

Population:
- genetic drift/bottleneck/founder effects, gene flow, allopatric speciation, sexual selection, sympatric speciation, natural selection = population allelic/gene frequencies altered or gain/loss of alleles/genes, reproductive fitness/differential success

(b) Draw a phylogenetic tree based on table, explain relationships, identify which is closely related to chicken
Phylogenetic_Tree.jpg
- cytochrome c: the more differences in amino acids of cytochrome c, less closely related
- penguin is most closely related to chicken
- three amino acids differing between penguin and chicken/penguin has fewest differences from chicken

(c) Describe 2 pieces of evidence that can be used to determine phylogeny and strength of each
Fossil:
- observe past organisms = direct evidence of common ancestor, follow evolution
Homology (Morphology):
- organismal structure/form, vestigial structures = simlilarities in form show common ancestry
Homology (Embryology/Development):
- comparison of reproductive strategies/life cycles: cell division, gamete production, gamete type, etc. = similarities in development show common ancestry
DNA Sequence
Homology (Reproduction)
Biogeography
Direct Observation/Behaviour

2009B #2

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(a) Alternation of generations
- gametophyte dominates nonvascular, sporophyte/flowering
- sporophyte heterosporous in flowering plants
- megasporangia, microsporangia

(b) Mechanisms that bring male/female gametes together
Nonvascular:
- need water to move sperm
- archegonia produces egg, antheridia produces sperm
Flowering:
- terrestrial, by wind, animal
- gametophytes, no antheridia/archegonia
- pollen: male gametophyte that produces gametes
- pollen tube carries sperm to nuclei

(c) Mechanisms that disperse offspring
Nonvascular:
- spores by wind/air
Flowering:
- seeds by wind/water/animal (with fur)
- winged seeds
- fruits lure animal
- seeds are protected by casing


2008 #4

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(a) Fertilization in flowering plants
Double Fertilization:
- sperm + egg = zygote (2n)
- sperm + 2 polar nuclei = endosperm food source (3n)
Pollen Tube Formation:
- pollen grain adheres to stigma
- germinates, grows pollen tube
- generative nucleus divides into 2 sperm nuclei
- development of embryo sac (female gametophyte)

(b) Pollen transfer
- wind
- animal
- water
- gravity (self pollination)

(c) evolutionary advantage preventing self fertilization


2008B #3

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2007B #1

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2007B #4

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2006 #1

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2006B #1

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2005 #3

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2004 #2

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2003 #1

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2003 #3

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2003B #4

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