AP Psychology : Genetics

Study concepts, example questions & explanations for AP Psychology

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Example Questions

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Example Question #11 : Genetics

Findings from twin studies indicate that genes influence a trait when __________ show more trait similarities than __________

Possible Answers:

dizygotic twins. . . monozygotic twins

siblings. . . parents

identical twins. . . fraternal twins

fraternal twins. . . identical twins

Correct answer:

identical twins. . . fraternal twins

Explanation:

Identical twins share 100% (or nearly 100%) of their genetic makeup, and fraternal twins only share about 50%. Because of this, twin studies can help clarify what traits have a genetic component rather than those associated with the environment. If a trait has a genetic component, then it will be clear because the identical twins will be more likely to share that trait than fraternal twins.

Identical twins are also called monozygotic (one fertilized egg that split) and fraternal twins are called dizygotic (two separate eggs that were fertilized). Siblings and parents are not the correct answers because the question asks about twin studies, not family studies.

Example Question #12 : Genetics

In an adoption study, it is found that adopted children score more similarly to their adopted parents than their biological parents on a specific trait. Given this information a professional would most likely agree with which of the following conclusions?

Possible Answers:

The environment has a greater effect on trait X than genetic influences

The trait is not heritable

Genetic and environmental influences on the trait are about the same

Genetics have a greater effect on trait X than environmental influences

Correct answer:

The environment has a greater effect on trait X than genetic influences

Explanation:

Adoption studies are a great way to study heritability because it separates genetic influences (e.g. biological parents) from environmental influences (e.g. adoptive parents). By examining traits in adoptees, one can reasonably conclude the specific influences of biological heredity. In this case, children scored more similarly to their adoptive parents, so it's likely that the environment had more to do with the expression of the specific trait than their genetic makeup did. 

Example Question #13 : Genetics

In order for a person to have blond hair, he or she must have two of the same genes; therefore, blond hair is considered to be which of the following kinds of genes?

Possible Answers:

Abnormal

Sex-linked

Recessive

Dominant

Phenotype

Correct answer:

Recessive

Explanation:

Recessive genes require that two genes be present in order for the person to display the phenotype or trait. This is true for blond and red hair. Dominant genes only require one gene to be present, which is true for brown hair. The definition of a phenotype is a person's observable characteristics. Sex-linked genes are located on sex chromosomes. Last, color blindness is sex-linked. 

Example Question #11 : Genetics

A recessive gene is a gene that is inherited but not usually expressed in a person's phenotype. True or false?

Possible Answers:

False, because the phenotype is a collection of non-observable traits

True

False, because the phenotype is a collection of observable traits

False, phenotypes are not related to genes.

False, because the genotype is unrelated to observable traits.

Correct answer:

True

Explanation:

Recessive genes are usually not expressed in a person's phenotype, that is, the set of observable traits a person possesses. Environmental factors can "bring them to light" in a manner of speaking but they are usually not expressed. Dominant genes, such as the gene for dark-colored eyes, are always expressed in the phenotype. 

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