im stuck on these questions for my study guide Please help! i don't want links. thanks
1. Which of the follwoing would be an appropriate measure of the phenotypic variation of a trait in a population?
a) the mean of the trait in the population
b) the standard deviation of the trait
c) the heritability of the trait
d) the allele frequency of genes affecting the trait.
2. Evolutionary change of a trait in a population under the effect of selection can occur only when
a) VE >0
b) h^2 >0
c) h^2 =0
d) VE =0
Biology is not a subject for which Jiskha has a staff expert. Anyone else who happens to read your question is welcome to respond.
1. To determine the appropriate measure of phenotypic variation for a trait in a population, you need to consider the different options provided and understand their relevance. Let's break down each option:
a) the mean of the trait in the population: This measure indicates the average value of the trait in the population. Although it provides some information about the central tendency of the trait, it does not fully capture the variation or spread of the trait within the population.
b) the standard deviation of the trait: This measure reflects the extent of variation or dispersion of the trait values around the mean. It provides a more comprehensive measure of phenotypic variation within the population.
c) the heritability of the trait: Heritability measures the extent to which genetic factors influence the variation of a trait in a population. It specifically focuses on the portion of the phenotypic variation that can be attributed to genetic differences. While heritability is a crucial measure for understanding the genetic basis of trait variation, it may not directly capture the overall phenotypic variation in a population.
d) the allele frequency of genes affecting the trait: This measure pertains to the frequency distribution of alleles (alternative forms of genes) that influence the trait in the population. While allele frequency may provide insights into genetic diversity, it may not necessarily directly inform about the phenotypic variation of the trait.
Considering these explanations, the more appropriate measure of phenotypic variation for a trait in a population would be b) the standard deviation of the trait.
2. To identify the condition necessary for evolutionary change of a trait in a population under the effect of selection, you need to understand the options provided:
a) VE > 0: VE represents the additive genetic variation for the trait, which indicates the genetic component of variation in the population. Evolutionary change can occur when there is additive genetic variation, so this option is correct.
b) h^2 > 0: h^2 represents heritability, which measures the proportion of phenotypic variation that is attributed to genetic factors. It provides information about the potential for a trait to respond to selection. A heritability greater than 0 suggests the presence of a genetic influence, and therefore evolutionary change can occur. This option is also correct.
c) h^2 = 0: A heritability of 0 means that the trait is not genetically influenced and does not respond to selection. Therefore, evolutionary change cannot occur. Hence, this option is not correct.
d) VE = 0: This option refers to a complete absence of additive genetic variation for the trait. Without genetic variation, selection would have no genetic material to act on, and thus no evolutionary change would occur. Therefore, this option is also correct.
Based on the explanations, the conditions necessary for evolutionary change of a trait in a population under the effect of selection are a) VE > 0 and b) h^2 > 0.