Block 7 Repro Genetics MCQ's Prt 2

The given scenario describes stabilizing selection. Stabilizing selection occurs when individuals with average or intermediate traits have a higher fitness compared to individuals with extreme traits. In this case, the giraffes closest to the average size are more likely to survive and reproduce because they can effectively reach the leaves on trees for food and their muscle size is suitable for supporting their body size. This leads to a narrowing of the trait distribution over time, as extreme traits are selected against.

The given description best fits the concept of "additive effects". It explains that the outcome of taking the statin Fluvostatin depends on the combination of desirable and undesirable alleles in the cholesteryl ester transfer protein and multidrug resistance transporter genes. The description suggests that the effect of these alleles is additive, meaning that the presence of desirable alleles will have a positive effect on the outcome, while the presence of undesirable alleles will have a negative effect. Therefore, the overall outcome is determined by the number of each type of allele present.

The recurrence risk for schizophrenia is greatest for siblings, such as a brother, of an affected individual. This is because siblings share a higher percentage of their genetic material compared to other relatives. Therefore, the chances of inheriting the genetic factors that contribute to schizophrenia are higher among siblings.

The correlation coefficient measures the strength and direction of the linear relationship between two variables. It ranges from -1 to 1, where -1 indicates a perfect negative correlation, 1 indicates a perfect positive correlation, and 0 indicates no correlation. By calculating the correlation coefficient, we can determine if there is a relationship between the two variables and the extent to which they vary together.

Forced sterilization policies on individuals with mental retardation in the last century were ethically questionable and wrong because most of the cases caused by dominant diseases come from new mutations. This means that sterilizing individuals with mental retardation would not have prevented the spread of these diseases, as the majority of cases are not inherited but rather result from spontaneous mutations. Therefore, the forced sterilization policies were ineffective in addressing the issue they were intended to solve.

Remember that monozygotic (MZ) twins have identical genotypes and dizygotic (DZ) twins share only 50% of their genetic information. Therefore if a trait is non-genetically determined then there should be no difference in the concordance rate (how often members of a twin pair show the same phenotype) between MZ and DZ twin pairs. If a trait has a genetic component then the rate of concordance is expected to be higher in MZ twins then in DZ twins.

When looking at the inheritance of multifactorial traits, as the number of affected children within a single family increases, the recurrence risk also increases.

Marfan syndrome is not an example of multifactorial inheritance because it is caused by a mutation in a single gene, specifically the FBN1 gene. Multifactorial inheritance involves the interaction of multiple genes as well as environmental factors. Pyloric stenosis, schizophrenia, and spina bifida are all examples of conditions that can be influenced by multiple genes and environmental factors, making them examples of multifactorial inheritance.

The additive genetic variance is at a maximum when q = 0.5. This is because the additive genetic variance is calculated using the formula 2pqa^2, where p and q represent the frequencies of the two alleles and a represents the effect of the allele on the phenotype. When q = 0.5, it means that both alleles are present in equal frequencies in the population. This allows for maximum variation in the genetic makeup of the individuals in the population, leading to a higher additive genetic variance.

The frequency of the "D" allele in population A is lower than in population B. Since "D" is incompletely dominant to "d", it means that individuals with the "Dd" genotype will have a phenotype that is intermediate between the "DD" and "dd" genotypes. This suggests that there is more genetic variation in population A, as there is a higher proportion of individuals with the "Dd" genotype. Therefore, the variance in population A is likely to be greater than in population B.

Hirschsprung disease is a condition characterized by the absence of nerve cells in certain parts of the colon, leading to problems with bowel movements. It is a congenital disorder that is present at birth. While Hirschsprung disease can occur in individuals with Down syndrome, the statement that it is more common in girls than in boys is incorrect. In fact, Hirschsprung disease is more commonly seen in boys than in girls.

The multifactorial threshold model suggests that the risk to relatives of an affected individual increases as the disease prevalence decreases. This means that if a disease is less common in the population, the risk to relatives of an affected individual is higher compared to a disease that is more common. This prediction is based on the idea that in a population with a lower disease prevalence, the genetic and environmental factors that contribute to the disease have a greater impact on the risk to relatives.

Dizygotic twins reared together will be most similar in ability to score high on an IQ test. This is because they share 50% of their genetic material (G), which contributes to their similarity in ability. Additionally, they are reared together, meaning they have similar environmental influences (E1 and E2). Therefore, the combination of genetic and environmental factors makes dizygotic twins reared together the most similar in ability to score high on an IQ test.

The F1 generation will have the largest phenotypic variance because it is a result of crossing two parents with different phenotypes (red and white) which produces an intermediate phenotype (pink). This mixing of traits increases the variation in the F1 generation compared to the P generation or the F2 generation, where the traits may segregate and become more uniform.

The realized heritability can be calculated by dividing the difference in mean bristle number between the offspring and the population mean by the difference in mean bristle number between the parents and the population mean. In this case, the difference in mean bristle number between the offspring and the population mean is 7.0 - 6.4 = 0.6, and the difference in mean bristle number between the parents and the population mean is 7.2 - 6.4 = 0.8. Dividing 0.6 by 0.8 gives 0.75, which is the realized heritability.

Correlation is a measure of dispersion about the mean in a population. It quantifies the relationship between two variables and indicates how they vary together. A high correlation value indicates a strong relationship, while a low correlation value indicates a weak or no relationship. Therefore, correlation is a suitable measure of dispersion about the mean as it provides information about the extent to which data points deviate from the mean and how they are related to each other.