Educational worksheet introducing pedigree charts for understanding genetic inheritance patterns.

Let’s work through this step by step.

We’re looking at a pedigree chart — that’s just a family tree that shows who has a certain trait (like blue eyes, or in this case, maybe something like “can roll tongue” or “has dimples”). The key tells us:

- Square = male
- Circle = female
- Black shape = person HAS the trait
- White shape = person does NOT have the trait

In the example pedigree shown:

Top row: Two parents — one black square (male with trait), one white circle (female without trait)
Bottom row: Their children — one black square (son with trait), one white circle (daughter without trait)

Now let’s answer each question based on this chart.

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1. Is the trait dominant or recessive?

Look at the parents: Dad has it (black), Mom doesn’t (white).
Their son has it, daughter doesn’t.

If the trait were recessive, then for someone to show it, they’d need two copies of the gene (one from each parent). But Mom doesn’t have the trait — so if it’s recessive, she can’t give a copy. That means the son couldn’t get two copies — so he shouldn’t have the trait… but he DOES.

That suggests the trait is dominant. Because even if you only get ONE copy (from Dad), you show the trait. Mom gives a normal gene, Dad gives the dominant one → son gets it and shows it. Daughter got Dad’s normal gene? Wait — no, Dad is black, meaning he HAS the trait. If it’s dominant, he could be either homozygous (two dominant genes) or heterozygous (one dominant, one normal). Since his daughter doesn’t have it, she must have gotten a normal gene from him — so Dad must be heterozygous (Dd), Mom is dd (no trait). Then kids: Dd (has trait) or dd (no trait). That fits!

✔ So the trait is dominant.

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2. What do the symbols represent?

From the key:

- Square = male
- Circle = female
- Filled-in (black) = has the trait
- Empty (white) = does not have the trait

So in this chart:

- Top left: Male with trait
- Top right: Female without trait
- Bottom left: Son with trait
- Bottom right: Daughter without trait

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3. How many offspring are there?

Count the shapes in the bottom row — that’s the children.

There are 2: one son, one daughter.

✔ Answer: 2

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4. Did the parents have any children who did NOT inherit the trait?

Yes — the daughter (white circle) does not have the trait.

✔ Answer: Yes

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Final Answer:

1. Dominant
2. Square = male, Circle = female, Black = has trait, White = no trait
3. 2
4. Yes