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40 Cards in this Set
- Front
- Back
Empiric risk is based on ______, which is the ___________. |
incidence; rate at which a certain event occurs
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To date, the most informative studies on how and to what degree heredity and the environment influence human traits have relied on data from |
monozygotic twins separated at birth |
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People with very light skin have _________ |
about the same number of melanocytes as people with very dark skin |
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Mutations and SNPs are similar in that |
they can both be changes in a DNA sequence |
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Multifactorial traits include |
both single gene and polygenic traits |
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If a trait has a large inherited component, then concordance among monozygotic twins will be |
considerably higher than that of dizygotic twins |
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Genes that help to control body weight encode the proteins |
leptin, ghrelin, and the melanocortin-4 receptor |
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Heritability refers to |
the genetic contribution to a phenotype in a population at a particular time |
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Geneticists designate heritability as "narrow" or "broad" to account for the fact that |
genes contribute to different degrees. Typically, dominant alleles are rare and can have a large impact and recessive alleles tend to be common with minor but additive effects |
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The DNA of dizygotic twins is |
as alike as the DNA of any two full siblings |
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Studies that implicate the environment in influencing body weight consider |
populations that split, with some people remaining in the homeland and others moving to areas where their diet changes dramatically, and they gain a great deal of weight |
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Traits that have both inherited and environmental causes are termed |
multifactorial |
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Heritability of a trait can change because |
the environment can change |
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Total ridge count" is |
a multifactorial trait that considers the number of ridges in whorls, loops, or arches of the finger pad skin |
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Mendel's laws |
apply to multifactorial traits but may be difficult to follow because different genes contribute in different degrees to a phenotype |
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An assumption of twin studies is that |
both twins of a pair have had similar experiences |
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The distinction between multifactorial and polygenic traits is that |
polygenic traits are caused by more than one gene, and multifactorial traits are caused by one or more genes as well as environmental influences |
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A continuously varying trait is |
height in humans |
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The number of genes that affect skin, hair, and eye color is about |
100 |
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Traditional ways of evaluating multifactorial traits include |
empiric risk and heritability |
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The empiric risk to a family member of an affected individual developing a disorder caused by a multifactorial trait |
increases with increasing relatedness to affected individuals |
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Genome-wide association studies have identified approximately __ regions that appear to harbor genes that control body weight |
50 |
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Mutations and SNPs are different in that |
mutations are rare and typically have a large effect on a phenotype, whereas SNPs are common and each may contribute a small degree to a phenotype |
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A brother and sister share ___ percent of their genes |
50 |
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In humans, heritability of clubfoot is 0.8. This means that expression of this condition is |
also influenced by environmental factors |
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The empiric risk that the monozygotic twin of a person with cleft lip also has cleft lift is ___ times the risk to a member of the general population who has no relatives with cleft lip |
400 |
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Two brothers share ___ percent of their genes |
50 |
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In a polygenic trait |
genes contribute to varying degrees, and alleles have differing degrees of impact |
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The proportion of shared genes between a grandparent and grandchild is ___ percent |
25 |
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The coefficient of relatedness indicates |
the proportion of genes that types of relatives share |
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Polygenic traits are |
determined by more than one gene |
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Fingerprint pattern is inherited, but also affected by the environment. An example of how the environment naturally can alter fingerprint pattern is |
a fetus touching the developing toe and finger pads to the wall of the amniotic sac |
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For a multifactorial, polygenic trait, the characteristic shape of the mathematical plot of frequency for each phenotype class is |
a bell curve |
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Skin color is not a good way to distinguish "races" of people because |
it is but one of many traits that vary within and between human populations |
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A cohort study looks at |
a large group of people over time, keeping track of specific health conditions or measures |
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The pattern of genetic transmission typical of a multifactorial trait is |
continuous variation of phenotypic expression |
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Concordance refers to |
percentage of twin pairs in which both express a trait among pairs in which at least one twin has the trait |
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Average height of college students increased throughout the 20th century because |
nutrition improved greatly in that time |
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DNA sequences that contribute to polygenic traits are called |
quantitative trait loci |
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Rasheed suffers terrible migraine headaches. They are likely caused by |
at least three genes and perhaps an environmental trigger, such as a food |