Question 1

The kinship between a step-mother and her step-children is

Accepted Answer

The kinship coefficient is a genetic measure, and a step-mother shares no genetic material with her step-children, so it is zero.

Question 2

Suppose that in a twin design family study, the average trait similarity within identical twins was no higher than for fraternal twins. The same environment was shared within all twin pairs. This outcome implies that

Accepted Answer

The fact that the average trait similarity within identical twins was no higher than for fraternal twins, despite sharing the same environment, suggests that there is little or no genetic influence on the trait. Therefore, the heritability of the trait is low.

Question 3

In a family study that applies the twin design, high heritability for a trait would be shown when

Accepted Answer

High heritability for a trait would be shown when identical twins show greater trait similarity than is found for fraternal twins. This suggests that genes play a greater role in the development of the trait, as identical twins share 100% of their genes whereas fraternal twins share only 50% on average. Option A is incorrect as high heritability would be shown when identical twins are similar on a trait. Option C and D are not related to heritability and are unrelated to the twin design.

Question 4

If you were a rat in Tryon's selective breeding experiment, which other rat would be your breeding partner if you excelled in the maze test?

Accepted Answer

Tryon's experiment involved selective breeding for maze-learning ability. Therefore, the best choice for a breeding partner would be a rat that also excelled in the maze test, as it would increase the likelihood of producing offspring with the desired trait.

Question 5

FAMILY STUDY is to SELECTIVE BREEDING as ____ is to ____.

Accepted Answer

Family study involves observation of traits and genetic relationships within a family, while selective breeding involves manipulating the breeding of organisms to achieve desired traits. Therefore, the relationship between the two is similar to the relationship between observation and manipulation in choice A. Choices B and C are not appropriate because they describe different biological processes, and choice D is not a comparable relationship.

Question 6

The heritability coefficient is LOW if the correlation for

Accepted Answer

The heritability coefficient is a measure of how much of the variation in a trait can be attributed to genetic differences. If the correlation for fraternal twins, who share about 50% of their genes, is equal to the correlation for identical twins, who share nearly 100% of their genes, it suggests that genetic factors do not play a large role in the variation of the trait, indicating a low heritability coefficient.

Question 7

Tryon's famous selective breeding experiment with rats showed that maze-learning skill

Accepted Answer

Tryon's experiment involved selectively breeding rats for their maze-learning abilities. The results showed that maze-learning skill was a heritable attribute, as the rats bred for high maze-learning abilities consistently outperformed the rats bred for low maze-learning abilities.

Question 8

In family studies of trait heritability, concordance rates are calculated instead of correlations when

Accepted Answer

Concordance rates are calculated when the trait phenotype appears in an all-or-none fashion, such as with genetic disorders. Correlations are used when the trait is continuous and can assume many values.

Question 9

If the correlation on a trait were .75 for identical twins, .55 for siblings, .23 for cousins, and .11 for genetically unrelated adopted siblings, one could conclude that

Accepted Answer

The correlation is highest for identical twins, who have the same genetic makeup, suggesting that heredity plays a significant role in the trait. However, the correlation is not perfect, indicating that environmental factors also contribute to the trait. The decreasing correlations for siblings, cousins, and adopted siblings suggest that the closer the genetic relationship, the higher the correlation, supporting the idea that heredity is a significant contributor. However, the decreasing correlations also suggest that environmental factors play a role, as they would be more similar for closer genetic relationships. Therefore, the best conclusion is that heredity is a prime contributor to that trait, but environment also plays a role.

Question 10

Tryon's experiments on selective breeding of rats to increase their maze-learning ability was related to

Accepted Answer

Tryon's experiments on selective breeding of rats to increase their maze-learning ability are an example of positive eugenics, which involves the selective breeding of individuals with desirable traits to improve the overall genetic quality of a population.

Question 11

For which trait would concordance rate be chosen for family study analysis, rather than correlation?

Accepted Answer

Concordance rate is chosen for family study analysis when studying traits that have a binary outcome (present or absent), such as sexual orientation. Correlation is better suited for analyzing continuous quantitative traits, such as height, intelligence score, and income level.

Question 12

Kinship is strongest for

Accepted Answer

Identical twins share 100% of their genes, making their genetic kinship the strongest among the options provided.

Question 13

A slogan of selective breeding would be,

Accepted Answer

The slogan "Breed best with best, repeat for many generations" accurately summarizes the concept of selective breeding. This process involves breeding animals with the most desirable traits, such as disease resistance or high milk production, to produce offspring with similar or improved traits. This is repeated over many generations to establish the desired characteristic in the breeding population. The other options do not accurately capture the essence of the selective breeding process.

Question 14

In family studies of heritability, the portion of group variability that is NOT attributed to heritability is attributed instead to

Accepted Answer

The portion of group variability that is not attributed to heritability in family studies is attributed to environmental influences. This includes both shared environmental factors, such as upbringing and family environment, as well as non-shared environmental factors, such as experiences unique to each individual. Random unsystematic variations may play a role in this, but they are not the primary factor. Personal volition and unknown psychical forces are not relevant to the study of heritability.

Question 15

The heritability coefficient is calculated from

Accepted Answer

The heritability coefficient is calculated from correlations within identical twin pairs and within fraternal twin pairs, as heritability refers to the proportion of variance in a trait that is due to genetics. The other options do not directly relate to the calculation of heritability.

Question 16

Because selective breeding is inappropriate for people, ____ research designs are applied instead for human studies of behavioral genetics.

Accepted Answer

Family study designs are commonly used in human studies of behavioral genetics instead of selective breeding. This involves the examination of the similarity of traits among family members, including twin studies, adoption studies, and family pedigrees. In vitro fertilization is not a research design, but rather a technique used to aid in fertilization. Independent assortment and crossing over are concepts related to genetics but are not research designs used in human studies of behavioral genetics.

Question 17

Kinship is a measure of

Accepted Answer

Kinship refers to the degree of genetic relatedness between individuals, which is determined by the extent to which they share the same genes.

Question 18

SELECTIVE BREEDING is to FAMILY STUDY as ____ is to ____.

Accepted Answer

Selective breeding is a process applied to animals (and plants), similar to how family studies are conducted in humans to understand genetic and hereditary traits.

Question 19

CONCORDANCE RATE is to CORRELATION COEFFICIENT as ____ is to ____.

Accepted Answer

Concordance rate and correlation coefficient are both measures of the degree of similarity between two variables. Categorical trait and continuous trait are also two different types of variables, with one being based on categories (such as eye color) and the other being based on a continuous spectrum (such as height). Therefore, D is the best choice.

Question 20

A trait of adopted children resembled that of their birth parents more than of their adoptive parents. This suggests that

Accepted Answer

The fact that adopted children resemble their birth parents more than their adoptive parents suggests that the trait in question has a high heritability, meaning that genetics play a larger role in determining the expression of the trait than environmental factors.

Quiz 2: Hereditary Influences on Development