L. PETERSON/AP BIOLOGY
Hereditary variations are essential to the evolution of populations.
Describe the different types of hereditary variability.
Explain how this variability can lead to the origin and
maintenance of species.
Total points possible for Part A and Part B = 18.
Candidates receiving 15, 16, 17,or 18 points are given a score of 15 for this essay.
PART A. (19 possible responses, with a maximum of 9 points given for this section)
For the seven mutation types that follow, 1/2 point is given for the naming, 1/2 point
is given for explaining, for a total of 7 possible responses; Maximum of 6 points given.
MUTATION TYPES: point, deletion, duplication, inversion, translocation, polysomy,
MUTATION ORIGIN: spontaneous or induced (listing inducing agent) - 1 point;
mechanism of induction or of mutation or relating process to evolution - 1 point;
mutations are rare, random, or usually deleterious - 1 point each;
EFFECTS OF MUTATIONS: Indicate with some explicitness the type(s) of phenotypic
effects - 1 point;
spell out how the gene change leads to phenotypic change - 1 point;
Recombination: independent assortment, crossing-over - 1 point;
role of sex in facilitating recombination - 1 point;
any consideration of asexual reproduction - 1 point;
"hidden" variation: epistasis - 1 point;
PART B. (12 possible responses, with a maximum of 9 points given)
Only inherited (germ-line) changes are important - 1 point;
POPULATION CHANGE DURING EVOLUTION
NATURAL SELECTION: The fittest, in relation to environment, survive - 1 point;
mechanism involves differential survival &/or reproduction - 1 point;
GENETIC DRIFT: random change in gene frequencies in small populations 1 point;
may account for large number of alleles in large populations - 1 point;
CONTINUOUSLY CHANGING ENVIRONMENT: leads to continuing evolution - 1 point;
GEOGRAPHIC: Isolation leads to divergence - 1 point;
mechanism for the build-up of difference - 1 point;
Sympatric: an isolating device; for example: seasonal, habitat, behavioral,
hybrid inviability, infertility - 1 point/with a maximum of 2 points;
AN EXAMPLE OF A CHANGED GENE OR PHENOTYPE OR FREQUENCY OR
1 point for each response, with a maximum of 2 points;