Short Answer1. Consider issues of both general cognitive ability and school achievement when answering thefollowing two <strong>questions</strong>. A. Does heritability change during development? And, B. Do geneticfactors contribute to developmental change (4 points)2. A. Give an example of both a trisomy and a single gene mutation that affect cognitive function(1 point). B. Provide one additional piece of information about each specific example you havechosen (2 points).3. Autism is the most heritable childhood disorder. It is really, really heritable. Yet despite this,the risk to siblings is only about 5%. Explain the seeming contradiction between these statements(1 point).
ANSWERSMultiple Choice1. A 2. D 3. C 4. C 5. D 6. C 7. B 8. A 9. B 10. D 11. C 12. A 13. BDefinitions1. Nonadditive genetic effect in which alleles at a locus interact rather than add up to affectbehaviour.2. Mouse that has loss of Reln gene function; experience motor control problems; reeler mousepups show reduced rates of ultrasonic vocalizations (have been used as autism model).3. Neurons that fire both when an individual performs an action or experiences a stimulusdirectly, and also when the action or stimulus is observed to occur in another.Short-Answer1. A. General cognitive ability does show that heritability changes during development; differentgenetic factors seem to come “on-line” in infancy, early childhood, middle childhood, etc. thatinfluence g, and studies show correlations between parents and children for g increase from lessthan 0.2 in infancy to over 0.3 by adolescence. School achievement, however does not (scoresare remarkably consistent across age ranges in different school subjects).1. B. For g, genetic factors contribute largely to continuity from childhood to adulthood,although some genetic change does exist; the results for school achievement is similar (i.e.,genetics contribute mostly to continuity with some support for change).2. A. Single Gene Mutations: Phenylketonuria (PKU), Fragile X syndrome, Rhett syndrome,Duchenne muscular dystrophy, Lesch-Nyhan syndrome, Neurofibromatosis type 1. Trisomy:Trisomy 21, Down syndrome, XXY, XYY, XXX.2. B. Any reasonable piece of info would be fine.3. Genes account for the majority of the variability with respect to the behaviour (autism) in thepopulation, so high heritability; but it’s very polygenic, so small allele differences can producelarge individual phenotypic differences (i.e., sibs not having autism).
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