Question 1

Axel produces a protein that causes mucus to obstruct his lungs and digestive tract.What disease does Axel have?

Accepted Answer

Cystic fibrosis is characterized by the production of thick, sticky mucus that can clog the lungs and obstruct the pancreas, leading to the symptoms described.

Question 2

If a trait has a heritability coefficient of .0, what would a behavioural geneticist conclude regarding the influence of genes and environment on this trait?

Accepted Answer

A heritability coefficient of 0 indicates that genetic factors do not contribute to the variation in the trait within a population, meaning the trait is not influenced by heredity.

Question 3

The correlation in IQ scores between monozygotic twins reared together is higher than that between dizygotic twins reared together.What does this difference indicate about role of environmental and genetic factors in the development of intellectual ability?

Accepted Answer

The higher correlation in IQ scores among monozygotic (identical) twins compared to dizygotic (fraternal) twins, even when reared together, suggests that genetic factors play a more significant role in the development of intellectual ability than environmental factors. This is because monozygotic twins share more genetic material (nearly 100%) than dizygotic twins (about 50% on average), leading to the conclusion that the similarities in IQ scores are more strongly influenced by genetics.

Question 4

Can intellectual disabilities and other problems associated with phenylketonuria be treated or prevented?

Accepted Answer

Intellectual disabilities and other problems associated with phenylketonuria (PKU) can be prevented by adhering to a strict low-phenylalanine diet from infancy. This dietary intervention helps manage phenylalanine levels in the body, preventing the harmful effects of PKU, including intellectual disabilities.

Question 5

Marcus has just finished a longitudinal twin study of intellectual performance.He included both monozygotic and dizygotic twin pairs in his study.Based on previous research, what would you predict he will find regarding age-related changes in the similarity of their intellectual scores?

Accepted Answer

Previous research suggests that as monozygotic (identical) twins age, their intellectual performance becomes more similar due to their identical genetic makeup. In contrast, dizygotic (fraternal) twins, who share about 50% of their genes, tend to show a decrease in similarity of intellectual performance as environmental factors play a more significant role over time.

Question 6

Suppose that a trait results from a recessive gene on the X chromosome.Which of the following best describes how this trait will be expressed?

Accepted Answer

Traits resulting from a recessive gene on the X chromosome are more often expressed in males because they have only one X chromosome. Females, having two X chromosomes, must have two copies of the recessive gene (be homozygous) to express the trait.

Question 7

Based on current research, how do heredity and environment contribute to adult personality?

Accepted Answer

Both heredity and environment play significant roles in shaping adult personality, with neither being solely responsible. Research indicates that genetic factors contribute to personality traits, but environmental influences, including life experiences and upbringing, also significantly shape personality development.

Question 8

Raj is colour blind, yet every one of his four children has normal colour vision.Which of Raj's grandchildren are most likely to be colour blind?

Accepted Answer

Colour blindness is often passed from a mother to her son, as it is a sex-linked trait carried on the X chromosome. Since Raj is colour blind, his daughters will be carriers of the colour blindness gene. When these daughters have children, their sons have a 50% chance of being colour blind, as they inherit one X chromosome from their mother.

Question 9

During the first few months of life, infants around the world vocalize quite similarly.What accounts for this phenomenon?

Accepted Answer

Canalization is a concept in developmental biology and psychology that refers to the tendency of a species to produce a phenotype regardless of variability in its environment or genotype. In the context of infant vocalizations, this means that all infants, regardless of their specific genetic makeup or the environment they are born into, will initially produce similar sounds. This is because the development of early vocalizations is highly canalized, following a species-specific pattern that is relatively unaffected by external factors.

Question 10

For many centuries, women were blamed if they failed to produce male offspring.Why was this unfair?

Accepted Answer

The sex of the offspring is determined by the father's sperm, which can carry either an X or a Y chromosome. The mother always contributes an X chromosome. Therefore, it is the father's genetic contribution that ultimately determines the sex of the child.

Question 11

Kaapo and Mina both have brown eyes, even though both have mothers with blue eyes.If eye colour is determined by simple dominant-recessive inheritance and brown is dominant, what percentage of their potential offspring will have brown eyes?

Accepted Answer

The answer of Kaapo and Mina both have brown eyes,...

Question 12

Matt is colour blind, yet both of his parents and his sibling have normal colour vision.One of Matt's grandparents is also colour blind.Which of Matt's grandparents is most likely to be colour blind?

Accepted Answer

Color blindness is often inherited in an X-linked recessive manner, meaning it is passed down on the X chromosome. Since Matt is male (XY), he must have inherited his Y chromosome from his father and his X chromosome from his mother. If his mother and father have normal color vision but Matt does not, his mother is likely a carrier of the color blindness gene. She must have received a colorblindness allele from one of her parents. Since her father (Matt's maternal grandfather) would have shown color blindness if he had a defective X chromosome (as males have only one X chromosome), it is more likely that the color blindness was passed down from a carrier mother (Matt's maternal grandmother) to Matt's mother, and then to Matt. However, the question states that one of Matt's grandparents is color blind, not a carrier, which means the initial explanation misinterpreted the question's conditions. Given this, the correct answer should be reconsidered based on the direct inheritance of color blindness, not carrier status.

Question 13

According to Scarr and McCartney, when are passive genotype/environment correlations most important?

Accepted Answer

Passive genotype/environment correlations are most important during infancy and early childhood because this is when parents or caregivers provide environments that are influenced by their own genetic tendencies, which the child also inherits. This means the environment is passively correlated with the child's genetic predispositions.

Question 14

Blair has an autosomal abnormality.Her IQ is low, and she has a number of distinctive physical features, including a protruding tongue and almond-shaped eyes.Based on this information, what syndrome does Blair have?

Accepted Answer

Blair's symptoms, including low IQ, a protruding tongue, and almond-shaped eyes, are characteristic of Down syndrome, which is caused by an extra copy of chromosome 21 (trisomy 21).

Question 15

Antonio has a sex chromosome abnormality.He is taller than most of his friends and his body proportions are slightly feminized.He scored within the normal range on a recent intelligence test, although his score for the verbal scale was lower than average.Based on this description, which syndrome does Antonio have?

Accepted Answer

Antonio's symptoms, including being taller than average, having slightly feminized body proportions, and scoring within the normal range on an intelligence test but lower on the verbal scale, are characteristic of Klinefelter syndrome. This condition involves an extra X chromosome (XXY), which can lead to the described physical and cognitive features.

Question 16

Scott and Brad are identical twins who are 8 years old.They both attend the same school and live together in the same household.How would Rowe and Plomin characterize these factors?

Accepted Answer

Shared environmental influences refer to those aspects of the environment that siblings (in this case, identical twins) share and that make them more similar to each other. Since Scott and Brad are identical twins living in the same household and attending the same school, these factors are considered shared environmental influences.

Question 17

Nathan and Ethan are monozygotic twins.However, people seldom get the two brothers mixed up because Ethan is five centimetres shorter than Nathan.What does the difference in height imply about the two brothers?

Accepted Answer

Monozygotic twins have identical genotypes, meaning they share the same alleles for all traits. The difference in height between Nathan and Ethan suggests that environmental factors, not genetic differences, have influenced their phenotypes, leading to a difference in gene expression related to height.

Question 18

Carrie is very physically fit and has excellent motor coordination.Because of these skills, her physical education teacher encourages her try out for her school's soccer team and gives her extra help at honing her skills.How would Scarr and McCartney explain the teacher's response to Carrie's behaviour?

Accepted Answer

Scarr and McCartney would explain the teacher's response to Carrie's behavior as an evocative genotype/environment interaction. This is because Carrie's inherent physical abilities and coordination (genotype) evoke responses from her environment (the teacher's encouragement and extra help) that further support and develop her skills.

Question 19

Suppose that a researcher finds that pairs of monozygotic twins are no more similar on a trait than are pairs of dizygotic twins.What can you conclude regarding the contribution of biological and environmental influences to the development of that trait?

Accepted Answer

If monozygotic twins (who share 100% of their genes) are no more similar on a trait than dizygotic twins (who share on average 50% of their genes), it suggests that genetic factors do not play a significant role in the development of that trait. Therefore, the heritability coefficient, which measures the proportion of variation in a trait attributable to genetic factors, would be low.

Question 20

Quillian has straight hair, which is a recessive trait.What can you conclude regarding Quillian's genotype for hair type?

Accepted Answer

Since straight hair is a recessive trait, Quillian must have two recessive alleles for that trait, making her genotype homozygous recessive.

Quiz 3: Hereditary Influences on Development