Question 1

Meristic traits are characterized by having phenotypes that are described by _____ .

Accepted Answer

Meristic traits are counted traits, meaning that the phenotype is described by a whole number count, such as the number of spines on a fish or the number of eggs in a bird's nest. The other answer choices are not relevant to describing phenotypes in this way.

Question 2

What is the term given to a random subset of individuals who are selected for measurement in a particular study?

Accepted Answer

The term given to a random subset of individuals who are selected for measurement in a particular study is called a sample. A sample is a subset of a larger population, and statistical analysis is performed on the sample to make inferences about the larger population. Placebos are substances or treatments that have no therapeutic effect but are used as a control in a clinical trial. Representatives are individuals chosen to represent a larger group or population. Controls are individuals or groups used as a comparison to the experimental group in a study.

Question 3

Continuous inheritance is often related to the term quantitative inheritance.Why?

Accepted Answer

In continuous inheritance,we consider each involved locus as having a quantitative input on the production of a single characteristic of the phenotype.In addition,although it may not always be the case,we would consider each gene product to be qualitatively similar.

Question 4

In the early part of the twentieth century,Nilsson- Ehle and others described experiments showing that multiple loci may be involved in the inheritance of certain traits.Such patterns are often called _____ .

Accepted Answer

The term "polygenic traits" refers to traits that are influenced by multiple genes, with each gene having a small effect on the trait. This is what Nilsson-Ehle and others observed in their experiments in the early twentieth century. Choices A, C, and D do not accurately describe this pattern of inheritance. "Continuous traits" refers to traits that vary along a continuum (e.g., height), but not necessarily due to multiple genes. "Indeterminate traits" and "threshold traits" are not common terms used to describe patterns of inheritance.

Question 5

If the proportion of F₂individuals resembling either of the two most extreme phenotypes the parental phenotypes)can be determined,what formula can be applied to determine the number of gene pairs involved?

Accepted Answer

The answer of If the proportion of F₂individuals resembling...

Question 6

Assume that a cross is made between tall and dwarf tobacco plants.The F₁generation showed intermediate height,while the F₂generation showed a distribution of height ranging from tall to dwarf,like the original parents,and many heights between the extremes.These data are consistent with which one of the following modes of inheritance?

Accepted Answer

The distribution of heights in the F2 generation suggests that multiple genes (polygenic inheritance) are involved, which is consistent with multiple-factor inheritance.

Question 7

Polygenic traits often demonstrate a  _____distribution when the phenotypes from a proper sample are represented in a histogram.

Accepted Answer

Normal distribution is commonly used to represent the distribution of complex traits which are controlled by multiple genes. The distribution is often bell-shaped, with most individuals in the middle and fewer individuals at the extremes of the distribution.

Question 8

Which of the following is not a statistical value often used to represent a sample when evaluating QTLs?

Accepted Answer

Mode is not a commonly used statistical value in QTL analysis, as it represents the most commonly occurring value rather than a measure of central tendency or variation that may be associated with a trait of interest. Mean, standard deviation, and variance are all commonly used in QTL analysis to evaluate the distribution of a trait and identify regions of the genome associated with its variation.

Question 9

When a trait is polygenic,but has a small number of discrete classes,it is said to be an _____ trait.

Accepted Answer

A threshold trait is one that is controlled by multiple genes but only has a few distinct phenotypic classes. These classes are determined by exceeding a certain threshold of genetic contribution, rather than by a continuum of variation.

Question 10

Bell- shaped distributions produced by plotting results of F₂and F₃crosses are typical of which type of inheritance?

Accepted Answer

Multiple-factor inheritance, also known as polygenic inheritance, involves the interaction of multiple genes to produce a phenotype. This often results in a continuous range of phenotypes, leading to a bell-shaped distribution when these phenotypes are plotted, as each gene contributes a small amount to the variation in the phenotype.

Question 11

Given the following numbers,calculate the mean: 10,12,14,16,18.

Accepted Answer

To find the mean, we need to add up all the numbers and divide by the total number of numbers.

10 + 12 + 14 + 16 + 18 = 70

We have a total of 5 numbers, so we divide the sum by 5:

70/5 = 14

Therefore, the mean is 14. Option D is the correct answer.

Question 12

s²= S X_i- X ²/n - 1 is the formula for calculating which statistical value?

Accepted Answer

The formula provided is for calculating variance, which measures the variability or spread of a set of data. The other options (covariance, standard deviation, mean) have different formulas for their calculations.

Question 13

Quantitative inheritance involves the interaction of a number of gene loci.The pattern of genetic transmission typical of quantitative inheritance is _____ .

Accepted Answer

Quantitative inheritance is characterized by continuous variation in phenotypic expression. This means that there is no clear-cut distinction between different phenotypes and instead, the traits are expressed as a range of values. Unlike Mendelian inheritance, the patterns of genetic transmission in quantitative inheritance involve the interaction of many gene loci, with each contributing a small effect towards the phenotype. There is no clear pattern of dominance and recessiveness, and the inheritance cannot be described by simple ratios such as 3:1 or 9:3:3:1.

Question 14

Assume that in the F₂of a series of crosses,1/64 of the offspring resemble one of the parents P .How many gene pairs are involved in producing these results?

Accepted Answer

If 1/64 of the offspring resemble one of the parents, this suggests that there is only one gene pair involved in determining this trait. This means that the trait is likely controlled by a single dominant or recessive allele, which is why such a small proportion of offspring show the phenotype. Therefore, only 3 gene pairs (2 alleles per gene) would be involved in producing these results.

Question 15

Assume that four polygenic gene pairs are involved in determining phenotypes of F₂.How many phenotypic classes are expected?

Accepted Answer

The number of phenotypic classes in a polygenic inheritance involving n gene pairs is given by the formula 2n + 1. For four gene pairs, it would be 2(4) + 1 = 9 phenotypic classes.

Question 16

Assume that you are studying a trait determined by a number of polygenes.If there are seven phenotypic categories,how many genes are probably involved?

Accepted Answer

Polygenes are traits that are determined by multiple genes, usually three or more. The number of phenotypic categories is not necessarily indicative of the number of genes involved. However, seven phenotypic categories suggest that the trait is likely influenced by multiple genes, likely around three. Therefore, the best answer is D, three genes.

Question 17

The 9:3:3:1 ratio is typical of a dihybrid cross in which complete dominance and independent assortment occur.What is the dihybrid ratio with independent assortment of polygenes?

Accepted Answer

The answer of The 9:3:3:1 ratio is typical of a...

Question 18

How many gene pairs are involved in generating a typical 1:4:6:4:1 ratio?

Accepted Answer

A 1:4:6:4:1 ratio is typical of a dihybrid cross involving two gene pairs, where each gene pair has two alleles showing incomplete dominance or codominance.

Question 19

When multiple genes contribute to the expression of a phenotype they are called _____ .

Accepted Answer

When multiple genes contribute to the expression of a phenotype in a additive manner, they are called additive alleles. This means that each gene adds a certain amount to the expression of the phenotype, and the total effect is the sum of each gene's contribution.

Question 20

What formula can be used to determine the number of categories phenotypes possible in the F₂results of a polygenic system?

Accepted Answer

The formula for determining the number of categories (phenotypes) possible in a polygenic system is 2n + 1, where n is the number of gene pairs. Therefore, the best choice is C. Choice A and B are not correct formulas for this purpose, and choice D appears to be a formula specific to a certain set of results and variables.

Quiz 25: Quantitative Genetics and Multifactorial Traits

Meristic traits are characterized by having phenotypes that are described by _____ .

What is the term given to a random subset of individuals who are selected for measurement in a particular study?

Continuous inheritance is often related to the term quantitative inheritance.Why?

In the early part of the twentieth century,Nilsson- Ehle and others described experiments showing that multiple loci may be involved in the inheritance of certain traits.Such patterns are often called _____ .

If the proportion of F₂individuals resembling either of the two most extreme phenotypes the parental phenotypes) can be determined,what formula can be applied to determine the number of gene pairs involved?

Polygenic traits often demonstrate a _____distribution when the phenotypes from a proper sample are represented in a histogram.

Which of the following is not a statistical value often used to represent a sample when evaluating QTLs?

When a trait is polygenic,but has a small number of discrete classes,it is said to be an _____ trait.

Bell- shaped distributions produced by plotting results of F₂and F₃crosses are typical of which type of inheritance?

Given the following numbers,calculate the mean: 10,12,14,16,18.

s²= S X_i- X ²/n - 1 is the formula for calculating which statistical value?

Quantitative inheritance involves the interaction of a number of gene loci.The pattern of genetic transmission typical of quantitative inheritance is _____ .

Assume that in the F₂of a series of crosses,1/64 of the offspring resemble one of the parents P .How many gene pairs are involved in producing these results?

Assume that four polygenic gene pairs are involved in determining phenotypes of F₂.How many phenotypic classes are expected?

Assume that you are studying a trait determined by a number of polygenes.If there are seven phenotypic categories,how many genes are probably involved?

The 9:3:3:1 ratio is typical of a dihybrid cross in which complete dominance and independent assortment occur.What is the dihybrid ratio with independent assortment of polygenes?

How many gene pairs are involved in generating a typical 1:4:6:4:1 ratio?

When multiple genes contribute to the expression of a phenotype they are called _____ .

What formula can be used to determine the number of categories phenotypes possible in the F₂results of a polygenic system?

Quiz 25: Quantitative Genetics and Multifactorial Traits

Meristic traits are characterized by having phenotypes that are described by _____ .

What is the term given to a random subset of individuals who are selected for measurement in a particular study?

Continuous inheritance is often related to the term quantitative inheritance.Why?

In the early part of the twentieth century,Nilsson- Ehle and others described experiments showing that multiple loci may be involved in the inheritance of certain traits.Such patterns are often called _____ .

If the proportion of F2 individuals resembling either of the two most extreme phenotypes the parental phenotypes) can be determined,what formula can be applied to determine the number of gene pairs involved?

Polygenic traits often demonstrate a _____distribution when the phenotypes from a proper sample are represented in a histogram.

Which of the following is not a statistical value often used to represent a sample when evaluating QTLs?

When a trait is polygenic,but has a small number of discrete classes,it is said to be an _____ trait.

Bell- shaped distributions produced by plotting results of F2 and F3 crosses are typical of which type of inheritance?

Given the following numbers,calculate the mean: 10,12,14,16,18.

s2 = S Xi - X 2/n - 1 is the formula for calculating which statistical value?

Quantitative inheritance involves the interaction of a number of gene loci.The pattern of genetic transmission typical of quantitative inheritance is _____ .

Assume that in the F2 of a series of crosses,1/64 of the offspring resemble one of the parents P .How many gene pairs are involved in producing these results?

Assume that four polygenic gene pairs are involved in determining phenotypes of F2.How many phenotypic classes are expected?

Assume that you are studying a trait determined by a number of polygenes.If there are seven phenotypic categories,how many genes are probably involved?

The 9:3:3:1 ratio is typical of a dihybrid cross in which complete dominance and independent assortment occur.What is the dihybrid ratio with independent assortment of polygenes?

How many gene pairs are involved in generating a typical 1:4:6:4:1 ratio?

When multiple genes contribute to the expression of a phenotype they are called _____ .

What formula can be used to determine the number of categories phenotypes possible in the F2 results of a polygenic system?

If the proportion of F₂individuals resembling either of the two most extreme phenotypes the parental phenotypes) can be determined,what formula can be applied to determine the number of gene pairs involved?

Bell- shaped distributions produced by plotting results of F₂and F₃crosses are typical of which type of inheritance?

s²= S X_i- X ²/n - 1 is the formula for calculating which statistical value?

Assume that in the F₂of a series of crosses,1/64 of the offspring resemble one of the parents P .How many gene pairs are involved in producing these results?

Assume that four polygenic gene pairs are involved in determining phenotypes of F₂.How many phenotypic classes are expected?

What formula can be used to determine the number of categories phenotypes possible in the F₂results of a polygenic system?