Question 1

Twin studies have found that:

Accepted Answer

Twin studies have consistently found that the similarity of identical twins raised apart is greater than the similarity of fraternal twins raised together. This suggests that genetic factors play a significant role in determining various aspects of behavior and personality. It is important to note that while genetics play a significant role in shaping human behavior, environmental factors also play a key role.

Question 2

Studies comparing the similarity of identical and fraternal twins who are raised together and apart are especially informative because:

Accepted Answer

Studies comparing identical and fraternal twins who are raised together and apart allow us to disentangle the effects of genetics and environment on various traits and behaviors, thus providing information about the relative importance of these factors. These studies are considered especially informative because identical twins share 100% of their genes while fraternal twins share only 50% on average, so any similarities or differences observed between them can be used to estimate the degree to which genetics and environment contribute to those traits or behaviors.

Question 3

A genetically determined trait may have an upper and lower limit,and the environment may determine the exact level of the trait that ultimately gets expressed.This is referred to as the concept of _________.

Accepted Answer

The concept of reaction range states that a genetically determined trait may have an upper and lower limit, while the environment may determine the exact level of the trait that ultimately gets expressed. This means that a person's genetic potential for a given trait can be influenced by environmental factors. Concordance refers to the degree of similarity between traits exhibited by individuals who share a common genetic makeup. Gene knockout is a genetic technique used to disrupt the function of a specific gene.

Question 4

Twin studies have consistently revealed that the factor(s)that account(s)for the least amount of variation in personality trait attributes is/are:

Accepted Answer

Twin studies have shown that shared family environment has less influence on personality traits compared to genetics and non-shared environmental factors.

Question 5

Although genetic factors are considerably important,they appear to account for about a certain percentage of the IQ variation between people in the United States.This percentage ranges from ______________:

Accepted Answer

Genetic factors are estimated to account for about 50 to 70 percent of the variation in IQ among individuals in the United States, according to studies on heritability.

Question 6

The reaction range principle suggests that genetics sets the upper and lower limits for a trait and _________ indicates where in that range a particular trait will fall.

Accepted Answer

The reaction range principle implies that genetics establish the boundaries for a trait, but the location within that range is determined by the environment. Therefore, the answer is B, environment. Choices A, C, and D are not relevant to the reaction range principle.

Question 7

What do we currently know about the specific sizes of reaction ranges for individuals?

Accepted Answer

The concept of reaction range refers to the potential variability in a trait due to environmental influences. Currently, there is no definitive evidence or consensus on whether the size of reaction ranges differs from one person to the next.

Question 8

If intelligence was completely determined by genetics,then which set of correlations would be the same?

Accepted Answer

The answer of If intelligence was completely determined by genetics,then...

Question 9

Researchers who believe in the concept of a reaction range are most likely to argue that intelligence:

Accepted Answer

The concept of a reaction range suggests that genes establish a range of possible outcomes for a particular trait or characteristic, but that the environment determines where within that range an individual will fall. Therefore, researchers who believe in the concept of a reaction range are likely to argue that intelligence is the product of the interaction between genetics and the environment.

Question 10

Though presently there is no quantifiable way to determine the reaction ranges of various intelligence-related traits,research on environmental enrichment programs and adoption studies suggest that the ranges could be:

Accepted Answer

Research on environmental enrichment programs and adoption studies suggest that the ranges for reaction ranges of various intelligence-related traits could be 15 to 20 IQ points.

Question 11

Scott and Shawn are identical twins raised together,whereas Tammy and Tracey are identical twins raised apart.Scott and Shawn are more similar on IQ than are Tammy and Tracey.This finding:

Accepted Answer

The answer of Scott and Shawn are identical twins raised...

Question 12

An adoption study examined the heritability of criminal behaviour in boys adopted at a young age.The level of boys' criminality was greatest when __________.

Accepted Answer

The study found that boys adopted at a young age were most likely to display criminal behavior when both their biological and adoptive fathers had criminal records. This suggests that both genetic and environmental factors contribute to the development of criminal behavior in these boys. If neither biological nor adoptive fathers had criminal records, it suggests that the boys may not have genetic or environmental risk factors for criminal behavior. If only biological fathers had criminal records, it suggests that genetic factors may play a stronger role than environmental factors. If only adoptive fathers had criminal records, it suggests that environmental factors may play a stronger role than genetic factors.

Question 13

Based on Hans Eysenck's work on genetic components of personality,research has shown that the personality trait neuroticism is related to increased action of the neurotransmitter __________.

Accepted Answer

Research has shown that the personality trait neuroticism is related to increased activity of the neurotransmitter serotonin.

Question 14

Barbara and Brenda are identical twins who were adopted at birth and raised by two different families.Andy and Andrew are identical twins raised together by their biological parents.When the four children entered high school they took an IQ test.Barbara and Andy each had scores of 110,while Brenda's IQ was measured at 120 and Andrew scored 108.These results support which of the following conclusions?

Accepted Answer

The fact that Barbara and Brenda, who have the same genetic makeup, have different IQ scores suggests that genetics alone cannot fully explain intelligence. Similarly, the fact that Andy and Andrew, who were raised in the same environment, have different IQ scores suggests that environment alone cannot fully explain intelligence. Therefore, a combination of genetics and environment likely contributes to intelligence.

Question 15

In general,which statement below best summarizes the outcome of the role of heredity and environment as they affect intelligence:

Accepted Answer

Research suggests that both heredity and environment play a role in determining intelligence, but they interact in a complex way. Genes provide the basic blueprint for intelligence, but environmental factors such as nutrition, education, and social experiences can also influence how these genes are expressed. Factors such as poverty, malnutrition, and lack of access to education can lead to lower intelligence scores, even in individuals with high genetic potential. On the other hand, positive environmental factors such as enriched learning environments and supportive social networks can enhance cognitive development, even in individuals with lower genetic potential. Therefore, it is best to consider heredity and environment as interacting factors in determining intelligence.

Question 16

Keith and Kirk are identical twins who were separated at birth and raised in different parts of the country in different environments.When as adults they were reunited,researchers compared them on several psychological characteristics.Compared to identical twins who have been raised together,Keith and Kirk probably have:

Accepted Answer

The different environmental influences that Keith and Kirk were raised in likely had an impact on their psychological characteristics, leading to fewer similarities between them compared to identical twins who were raised together. This is supported by research on the effects of nature vs. nurture on human development.

Question 17

According to the notion of a reaction range for intelligence,if Dean has a reaction range that is equivalent to Shannon's and Shannon has experienced a considerably more enriched environment compared to Dean,who would have a higher intelligence score?

Accepted Answer

Shannon would have a higher intelligence score because, with the same reaction range, the more enriched environment allows her to reach closer to the upper limit of her potential intelligence.

Question 18

Which of the following statements regarding the similarity of IQ between twins is FALSE?

Accepted Answer

The statement that the correlation for fraternal twins raised together is higher than for identical twins raised apart is false. In reality, the opposite is true - the correlation for identical twins raised apart is higher than for fraternal twins raised together. This indicates a stronger genetic influence on IQ than environmental factors.

Question 19

One problem with studying identical and fraternal twins raised together or apart is that:

Accepted Answer

Identical twins raised together may be treated more similarly than fraternal twins, which could lead to greater behavioral similarity due to environmental factors rather than genetic ones.

Question 20

An adoption study examining the heritability of criminal behaviour found that people who had biological parents and adoptive parents who both had criminal records were the most likely to be criminals themselves.This example was presented to demonstrate.

Accepted Answer

This example illustrates the interaction between genetic factors (biological parents with criminal records) and environmental factors (adoptive parents with criminal records) in influencing criminal behavior, demonstrating how both sets of factors can work together to shape outcomes.

Quiz 4: Genes, evolution, and Behaviour