Pedigree Inquiry printable pdf download

Pedigree Inquiry

Name ______________________________________________________ Period ___________ Date ___________________

Pedigree Inquiry

Overview: A pedigree chart demonstrates the inheritance of a particular trait in a family.

Females are represented by a circle, males by a square. A shaded circle or square represents

that the individual has the particular trait or disorder expressed in their phenotype.

Horizontal lines represent marriages, and vertical lines represent their offspring. Recessive

traits can skip a generation, while dominant traits tend not to. If there are more males with

a particular trait than females, the trait is probably sex-linked. Genotypes for sex-linked

traits must be written as superscripts on the X chromosome. Mothers with a sex-linked

recessive trait will always have sons with the trait. If any males in the family are carriers,

then the trait is autosomal. If the trait is autosomal, you must write the genotypes using

only lower and uppercase letters.

Part I: The Ling Family

Use the pedigree below to answer the following questions about the inheritance of

colorblindness in the Ling family.

1. How many males in this family are colorblind?

2. How many males are normal-sighted?

3. How many females are colorblind?

4. How many females are normal-sighted?

5. Is colorblindness a sex-linked or autosomal trait? Explain how you can determine this

from the Ling family pedigree.

6. How many generations are present on this pedigree?

7. How many children did the couple in the first generation have?

8. List the genotypes for all males in the Ling family (X

= normal allele, X

= colorblind

allele).

Pedigree Inquiry