Charting Lineage: Pedigree Chart Reading Quiz

1. How many affected individuals are on this pedigree chart, and how can you tell?

6, those who are shaded black

3, those who are shaded black with a slash

11, those who have a slash

12, those who are not shaded

The correct answer is 6, those who are shaded black. This can be determined by looking at the pedigree chart and identifying the individuals who are shaded black. These shaded individuals represent the affected individuals in the chart.

Explanation

The correct answer is 6, those who are shaded black. This can be determined by looking at the pedigree chart and identifying the individuals who are shaded black. These shaded individuals represent the affected individuals in the chart.

2. How many members of this family are deceased?

11

6

9

4

The answer is 11 because it is the highest number among the options provided. This suggests that out of the given options, 11 is the number of deceased members in the family.

Explanation

The answer is 11 because it is the highest number among the options provided. This suggests that out of the given options, 11 is the number of deceased members in the family.

3. The parents that begin this chart are the first generation. How many of their children were albinos?

2

6

4

The question asks how many of the first generation's children were albinos. The answer is 2, indicating that only two children out of the total number of children had albinism.

Explanation

The question asks how many of the first generation's children were albinos. The answer is 2, indicating that only two children out of the total number of children had albinism.

4. Is this chart following a dominant or recessive trait and how do you know?

Dominant, because it shows up only in males

Dominant because most of the people affected have died

Recessive because it did not show up in every generation

Recessive because it shows up only in males

The correct answer is recessive because it did not show up in every generation. This suggests that the trait is not consistently present in each generation, which is a characteristic of a recessive trait. If the trait was dominant, it would be expected to appear in every generation, as it would be passed on from at least one affected parent to their offspring.

Explanation

The correct answer is recessive because it did not show up in every generation. This suggests that the trait is not consistently present in each generation, which is a characteristic of a recessive trait. If the trait was dominant, it would be expected to appear in every generation, as it would be passed on from at least one affected parent to their offspring.

5. If this chart is following the recessive trait for albinism (people who are albinos, aa), then what is the genotype of the parents at the top of the chart?

Aa and Aa

Aa and aa

Aa and Aa

AA and AA

Based on the information given, the chart is following the recessive trait for albinism. This means that individuals who are albinos have the genotype aa. Therefore, the genotype of the parents at the top of the chart must be Aa, as they are carriers of the recessive allele but do not express the trait themselves.

Explanation

Based on the information given, the chart is following the recessive trait for albinism. This means that individuals who are albinos have the genotype aa. Therefore, the genotype of the parents at the top of the chart must be Aa, as they are carriers of the recessive allele but do not express the trait themselves.

6. In the third generation, what is the genotype of the only child of the third mating from the left ?

Aa

AA

A

Aa

For a child to be affected by an autosomal recessive condition, both alleles must be the recessive form (a). Since both parents are carriers (Aa), they each contributed a recessive allele, making the child's genotype aa.

Explanation

For a child to be affected by an autosomal recessive condition, both alleles must be the recessive form (a). Since both parents are carriers (Aa), they each contributed a recessive allele, making the child's genotype aa.