Pedigree Analysis Worksheet

Name:

Date:

📚 What is Pedigree Analysis?

A pedigree is like a family tree that shows how traits (characteristics) are passed down through generations. Scientists use pedigrees to track inherited conditions like eye colour, blood type, or genetic disorders through families.

Key Symbols:

• Square = Male

• Circle = Female

• Filled/Shaded shape = Has the trait

• Empty shape = Does not have the trait

• Horizontal line = Marriage/partnership

• Vertical line = Children

1. What does a filled square represent in a pedigree?

A female with the trait

A male with the trait

A female without the trait

A male without the trait

2. Which symbols are used in pedigree charts? (Tick all that apply)

Circles for females

Triangles for children

Squares for males

Lines to show relationships

🔍 Analysing Pedigrees

Example: In the Brown family, we're tracking a genetic condition. Generation I shows the grandparents, Generation II shows the parents, and Generation III shows the children.

3. If both parents do not show a trait, but one of their children does, the trait is likely:

Dominant

Recessive

Neither

4. What does it mean if a trait "skips generations"?

5. In a family where the father has brown eyes (dominant trait) and the mother has blue eyes (recessive trait), what eye colours could their children have?

Brown eyes only

Blue eyes only

Brown or blue eyes

Green eyes

6. Complete the sentence: A trait that appears in every generation is likely to be ____________.

✏️ Apply Your Knowledge

7. Draw a simple pedigree showing three generations where a recessive trait appears in the grandparents and grandchildren, but not the parents.

8. Explain why pedigree analysis is useful for doctors and genetic counsellors.

9. A couple wants to know the chance of their child inheriting a genetic condition. The man's family has no history of the condition, but the woman's brother has it. What information would a genetic counsellor need to help them?