Test: Behavior and Genetics - 1 - MCAT MCQ

A codon is a specific sequence of three nucleotides in mRNA that codes for a specific amino acid during protein synthesis. Each codon corresponds to a particular amino acid, allowing the genetic code to be translated into a sequence of amino acids, which are the building blocks of proteins. Therefore, a codon specifies the incorporation of a specific amino acid into a growing polypeptide chain.

The human genome is estimated to contain approximately 20,000 protein-coding genes. These genes provide the instructions for building the various proteins that are essential for the structure, function, and regulation of cells in the human body. It's important to note that the number of protein-coding genes is significantly smaller than the total number of genes in the human genome, which includes non-coding genes and regulatory sequences.

Temperament refers to the innate or genetically influenced aspects of an individual's character that are present from early infancy and remain relatively stable throughout their lifetime. It is believed to be established before significant environmental influences come into play. Temperament traits are often seen as biologically based and can influence various aspects of behavior, emotion, and social interaction. In contrast, personality is a broader term that encompasses both innate and acquired traits, including temperament, as well as other characteristics that can be influenced by environmental factors and individual experiences. Therefore, the focus of the researcher's thesis aligns with the concept of temperament.

This statement accurately describes simple and complex traits. Simple traits are basic, easily observable characteristics of behavior and personality that can be attributed to a single gene or a small number of genes. These traits tend to have clear-cut manifestations and can often be easily categorized. Examples of simple traits include eye color, blood type, or the ability to taste certain flavors. On the other hand, complex traits are more nuanced and multifaceted. They are influenced by multiple genes as well as environmental factors, making them more challenging to study and understand. Complex traits, such as intelligence, personality traits, or psychological disorders, are not easily explained by a single gene and are often the result of intricate interactions between multiple genetic and environmental factors.

In this scenario, the fact that Tom and Andy are monozygotic (identical) twins suggests that they share the same genetic material. However, because they were separated at birth and raised in different families, their environments differ to some extent. While their adoptive parents may have similar expectations and athletic backgrounds, there could be other environmental factors that influence their athletic ability differently.

The assumption that can be made is that both genetic and environmental factors contribute to their athletic ability, but it is difficult to determine the extent of each factor's influence. This is because the influence of genes and environment cannot be isolated or separated in this particular case. Therefore, the specific contribution of genes to their athletic ability remains unclear.

The described behavior of a newborn baby turning her head toward something that touches her cheek and making sucking motions with her mouth is an example of innate behavior. Innate behaviors are instinctual and are present in an organism from birth or shortly after birth, without requiring prior learning or experience. These behaviors are often genetically programmed and serve essential survival functions. In this case, the newborn's turning of the head and sucking motions are reflexive responses that are present from birth and do not require conscious thought or learning.

The heritability estimate of .40 indicates that approximately 40% of the variability in disordered eating in the group of young women can be attributed to genetic factors. Heritability estimates quantify the proportion of phenotypic variation in a trait that can be attributed to genetic differences among individuals within a specific population. Therefore, this finding suggests that genetic factors play a significant role in the development of disordered eating in this particular group. It does not imply that disordered eating is solely determined by genetics or that it applies to all groups of young women. The estimate is specific to the group studied and does not indicate the presence of a specific gene for disordered eating.

Heritability refers to the proportion of phenotypic variation in a population that is due to genetic differences. When a population is in a uniform environment, it means that individuals within the population are exposed to similar environmental conditions. In such a case, any observed differences in phenotypic traits are more likely to be influenced by genetic factors rather than environmental factors. This allows for a higher degree of heritability because the variation in traits can be attributed more strongly to genetic differences rather than environmental influences. In contrast, in a population with a varied environment, the phenotypic variation is more likely to be influenced by different environmental factors, which can mask the effects of genetic variation and result in a lower heritability estimate.

Adoption studies involve comparing the similarities between adopted individuals and their adoptive families (environmental influence) and their biological families (genetic influence). By examining the differences and similarities, researchers can estimate the contribution of genetic factors to various behaviors.

Candidate genes are specific genes that are hypothesized to be involved in a particular behavior or trait based on prior research. The association between the dopamine receptor gene (DRD4) and risk-taking behavior has been explored in several studies, suggesting a potential link between genetic variations in this gene and individual differences in risk-taking tendencies.