Chapter 22
F
Monogenic inheritance centers around additive alleles and is quantitative T/F
T
Monozygotic twins are useful in human heritability studies because they are genetically identical. T/F
F
Most quantitative traits have high broad-sense heritability estimates (H2 values). T/F
T
Discontinuous variation describes a trait controlled (usually) by only one gene that cannot be quantified. QTLs are quantitative trait loci, which represent traits controlled by more than one gene that can be quantified. T/F
F
Fraternal twins are as genetically similar as monozygotic twins. T/F
3
In a cross involving polygenic inheritance, only 2/125 of the offspring (F2) were as extreme as one of the P1 parents. How many gene pairs are involved?
18 cm
In a cross involving the polygenic trait for plant height, the shortest and tallest plants are 6 cm and 24 cm, respectively. What height should all F1s display if homozygous 12-cm and 24-cm plants are crossed, assuming their environments are the same?
F
In the analysis of broad-sense heritability, an H2 value of 0.5 indicates the contributions by genetic and environmental factors to phenotypic variation are unequal T/F
T
Individual genes affecting a quantitative trait are inherited in a Mendelian fashion. T/F
multifactorial inheritance
Phenotypes that exhibit continuous variation are often the result of _______.
F
Quantitative trait loci (QTLs) are genes that are linked T/F
F
The difference between multiple alleles and additive alleles is that multiple alleles are different forms of the same gene. Additive alleles are alleles of different genes that affect different traits. T/F
T
The following is an example of a meristic trait: Number of bristles on a fruit fly T/F
T
The following statements is NOT a major point in the multiple-factor hypothesis: Each gene locus involved in the phenotype may be occupied by either an additive allele, which contributes to the phenotype, or a nonadditive allele, which offsets the additive alleles. T/F
F
The inheritance of threshold traits differ from inheritance of continuous variation traits because Continuous variation traits exhibit a small number of discrete phenotypes. Threshold traits exhibit a continuous range of phenotypes that cannot be classified into discrete categories. T/F
T
This value is an estimate of how much the means of similar samplings of the same population might vary: Standard error of the mean T/F
T
Two classes of traits that do NOT show continuous variation are meristic traits, which do not have an infinite range of phenotypes, and threshold traits, which have a small number of discrete phenotypic classes. T/F
T
Two samples with identical means do not necessarily have the same standard deviation. T/F
Sample variance
Which term describes the degree to which values diverge from the mean?
artificial selection
Which term describes the procedure of selecting a specific group of organisms from an initially heterogeneous population for future breeding purposes?
Broad-sense heritability
Which term is defined as a measure of the variation in a phenotype (for a polygenic trait in a given population) due to genetic factors?
95.5%
Within a normal distribution, what percentage of the sampling will be expected to fall within the mean plus or minus two standard deviations (X±2s)?