Pedigree charts worksheet - Free Printable

Problem Analysis:

The worksheet focuses on understanding pedigrees and the inheritance of a recessive genetic trait, albinism, in humans. Albinism is caused by a recessive allele (`a`), while the dominant allele (`A`) results in a normal phenotype. The genotypes and their corresponding phenotypes are as follows:
- AA: Normal (homozygous dominant)
- Aa: Normal (heterozygous carrier)
- aa: Albino (homozygous recessive)

We will solve each part of the worksheet step by step.

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Part 1: Genotypes and Phenotypes

#### Given:
- AA = ?
- Aa = ?
- aa = ?

#### Solution:
- AA: Homozygous dominant → Normal
- Aa: Heterozygous carrier → Normal
- aa: Homozygous recessive → Albino

So, the answers are:
- AA = Normal
- Aa = Normal
- aa = Albino

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Part 2: Pedigree Analysis (First Pedigree)

#### Pedigree Description:
- Circles represent females.
- Squares represent males.
- Shaded symbols indicate individuals with albinism (`aa`).

#### Questions:
1. How many children does the couple have?
2. What is the sex of the oldest child?
3. How many grandchildren does the couple have?

#### Analysis:
- The couple has 3 children (one circle and two squares).
- The oldest child is the female (leftmost child).
- The couple has 4 grandchildren (two from the first child and two from the second child).

#### Answers:
1. 3 children
2. Female
3. 4 grandchildren

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Part 3: Pedigree Analysis (Second Pedigree)

#### Pedigree Description:
- Circles represent females.
- Squares represent males.
- Shaded symbols indicate individuals with albinism (`aa`).

#### Questions:
1. How many children did the original couple have?
2. How many grandchildren do they have?
3. How many of their grandchildren are albino?
4. Create an extension to the pedigree to show the albino granddaughter marrying and having a son who is NOT albino.

#### Analysis:

##### Step 1: Counting Children and Grandchildren
- The original couple has 2 children (one female and one male).
- They have 5 grandchildren (2 from the daughter and 3 from the son).

##### Step 2: Identifying Albino Grandchildren
- The shaded symbols indicate albinism (`aa`).
- There are 3 grandchildren with albinism.

##### Step 3: Creating the Extension
- The albino granddaughter (`aa`) marries someone who is not albino. For the son to be not albino, the partner must be at least a carrier (`Aa`) or homozygous dominant (`AA`).
- Possible genotypes for the partner:
- If the partner is `AA`, all offspring will be `Aa` (normal).
- If the partner is `Aa`, there is a 50% chance of having a normal child (`Aa`) and a 50% chance of having an albino child (`aa`).

Since the problem specifies that the son is not albino, we can assume the partner is either `AA` or `Aa` (but the son must be `Aa`).

#### Answers:
1. 2 children
2. 5 grandchildren
3. 3 grandchildren are albino

##### Extension of the Pedigree:
- Draw the albino granddaughter (`aa`) marrying a non-albino individual (`Aa` or `AA`).
- Show their son as `Aa` (normal).

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Final Answer:

1. Part 1:
- AA = Normal
- Aa = Normal
- aa = Albino

2. Part 2:
- a) 3 children
- b) Female
- c) 4 grandchildren

3. Part 3:
- a) 2 children
- b) 5 grandchildren
- c) 3 grandchildren are albino
- d) Extension pedigree showing the albino granddaughter marrying a non-albino and having a son who is not albino.

Boxed Final Answer:
\[
\boxed{
\text{See detailed explanations above.}
}
\]