Question 1

Which of the following best describes a SNP (single nucleotide polymorphism) as used in ancestry testing?

Accepted Answer

A single base pair change in the DNA sequence that can be used to assess genetic variability among populations.

Question 2

The fixation index ($$F_{ST}) is $$used in population genetics to measure:

Accepted Answer

The degree of genetic differentiation between populations, ranging from 0 (no differentiation) to 1 (complete differentiation).

Question 3

Given two populations: Population 1 is homozygous for allele C and Population 2 is homozygous for allele T. If the total population is 50% C and 50% T, what is the $$F_{ST}$$ value?

Accepted Answer

$$F_{ST} = \frac{0.5 - 0}{0.5} = 1$$

Question 4

Which of the following factors can increase the $$F_{ST}$$ value between two populations?

Accepted Answer

Genetic drift leading to allele fixation in isolated populations.

Question 5

In a study of 2.8 million SNPs across African, European, Chinese, and Japanese populations, the overall $$F_{ST}$$ was found to be 0.1. What does this indicate about genetic diversity among these groups?

Accepted Answer

There is low genetic differentiation, indicating more genetic similarity than difference.

Question 6

A SNP in the SERA1 gene is present in 85% of Africans but absent in other ethnic groups. What evolutionary mechanism most likely explains this distribution?

Accepted Answer

Natural selection favoring the SNP in regions where malaria is prevalent.

Question 7

Why is it difficult to reconstruct a complete genetic sequence for an individual’s ancestors beyond a few generations?

Accepted Answer

Genetic information is lost due to random assortment and recombination, leading to gaps in inherited segments.

Question 8

Which of the following statements about mitochondrial DNA (mtDNA) inheritance is correct?

Accepted Answer

mtDNA is inherited from the mother and passed to all her children.

Question 9

If a population has an $$F_{ST}$$ value of 0.7 for a particular SNP, what does this suggest?

Accepted Answer

There is extreme genetic differentiation for this SNP between populations.

Question 10

Which of the following best explains why ancestry testing using SNPs can only provide limited information about distant ancestors?

Accepted Answer

Recombination and random segregation cause loss of ancestral genetic segments over generations.

Question 11

Which of the following is a correct interpretation of a low $$F_{ST}$$ value (e.g., $$F_{ST} \u003c 0.05) $$between two human populations?

Accepted Answer

There is little genetic differentiation; the populations are genetically similar.

Question 12

Which of the following is a limitation of using Y chromosome analysis for ancestry testing?

Accepted Answer

It only traces the paternal lineage and ignores maternal ancestry.

Question 13

A SNP associated with the NPP1 gene is found in the majority of non-African populations but is absent in Africans. What does this pattern most likely reflect?

Accepted Answer

A selective advantage for the SNP in non-African environments.

Question 14

Which of the following best describes the main finding regarding human genetic diversity from the study of 2.8 million SNPs?

Accepted Answer

Most genetic diversity is found within populations, with only 5-10% between populations.

Question 15

Which process can cause a small group of individuals to become genetically distinct from the main population, thereby increasing $$F_{ST}$$?

Accepted Answer

Founder effect due to migration and subsequent isolation.

Question 16

Why are certain SNPs, such as those with high $$F_{ST}$$ values, particularly useful in ancestry testing?

Accepted Answer

They show strong differentiation between populations, helping to identify population-specific ancestry.

Question 17

Which of the following is true regarding the inheritance of autosomal DNA compared to Y chromosome and mitochondrial DNA?

Accepted Answer

Autosomal DNA is inherited equally from both parents, while Y chromosome and mitochondrial DNA are inherited uniparentally.

Question 18

Which of the following scenarios would most likely result in a decrease in $$F_{ST}$$ between two populations?

Accepted Answer

Increased migration and interbreeding between the populations.

Question 19

Which of the following best explains why most mutations observed in population studies are rare?

Accepted Answer

Most mutations are deleterious and are removed by natural selection.

Question 20

Which of the following is a reason why ancestry testing can sometimes fail to identify certain ancestral lineages?

Accepted Answer

Genetic segments from some ancestors may be lost due to random segregation and recombination over generations.

Population Genetics and Ancestry Testing: SNPs, Fixation Index, and Genetic Inheritance

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