Detailed human pedigree chart illustrating the inheritance of three traits—attached earlobes, tongue rolling, and colorblindness—across four generations, using standard symbols to denote affected and unaffected individuals.

Problem Analysis and Solution

The task involves analyzing three human pedigrees to determine whether specific traits are dominant or recessive. Let's solve each part step by step.

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Part A: Attached Earlobes

#### Pedigree Description:
- The pedigree shows the inheritance of attached earlobes over four generations.
- Key symbols:
- Black-filled squares/circles: Individuals with the trait (attached earlobes).
- Unfilled squares/circles: Individuals without the trait (free earlobes).

#### Question:
Is the trait for attached earlobes dominant or recessive? How do you know?

#### Solution:
1. Identify the Pattern:
- In the first generation (P₁), both parents have free earlobes (unfilled symbols).
- One of their sons (F₁) has attached earlobes (black-filled square).
- None of the other offspring in F₁, F₂, or F₃ have attached earlobes.

2. Analyze the Phenotypes:
- Since both P₁ parents have free earlobes but produce an offspring with attached earlobes, the attached earlobe trait must be recessive.
- For a recessive trait to appear, both parents must carry at least one copy of the recessive allele. Here, the parents must be heterozygous (carriers) for the recessive allele.

3. Conclusion:
- The trait for attached earlobes is recessive.
- Explanation: A recessive trait appears when both parents are carriers (heterozygous) and pass on the recessive allele to the offspring.

#### Final Answer for Part A:
$$
\boxed{\text{Recessive}}
$$

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Part B: Tongue Rolling

#### Pedigree Description:
- The pedigree shows the inheritance of tongue rolling.
- Key symbols:
- Black-filled squares/circles: Individuals who can roll their tongues.
- Unfilled squares/circles: Individuals who cannot roll their tongues.

#### Question:
Is this trait dominant or recessive? Explain.

#### Solution:
1. Identify the Pattern:
- In the first generation (P₁), one parent can roll their tongue (black-filled circle), and the other cannot (unfilled square).
- In the second generation (F₁), some individuals can roll their tongues (black-filled symbols), while others cannot (unfilled symbols).
- In the third generation (F₂), there are individuals who can roll their tongues and those who cannot.

2. Analyze the Phenotypes:
- The presence of both phenotypes (tongue rollers and non-tongue rollers) in subsequent generations suggests that the ability to roll the tongue is a dominant trait.
- If the trait were recessive, we would expect all offspring of a heterozygous parent and a homozygous recessive parent to show the recessive phenotype. However, here we see both phenotypes, indicating dominance.

3. Conclusion:
- The trait for tongue rolling is dominant.
- Explanation: A dominant trait is expressed even if only one copy of the dominant allele is present. The presence of both phenotypes in multiple generations supports this.

#### Final Answer for Part B:
$$
\boxed{\text{Dominant}}
$$

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Part C: Colorblindness

#### Pedigree Description:
- The pedigree shows the inheritance of colorblindness, which is a sex-linked trait (X-linked recessive).
- Key symbols:
- Black-filled squares/circles: Individuals with colorblindness.
- Unfilled squares/circles: Individuals with normal color vision.

#### Question:
Is this trait dominant or recessive? Is the mother of the colorblind girl in the F₃ generation colorblind, a carrier, or a person with normal color vision? Explain.

#### Solution:
1. Identify the Pattern:
- Colorblindness is known to be an X-linked recessive trait.
- In the pedigree:
- A male in P₁ is colorblind (black-filled square).
- His daughter in F₁ is not colorblind (unfilled circle).
- In F₂, a male is colorblind (black-filled square).
- In F₃, a female is colorblind (black-filled circle).

2. Analyze the Phenotypes:
- Since colorblindness is X-linked recessive:
- Males need only one copy of the recessive allele (on their single X chromosome) to be colorblind.
- Females need two copies of the recessive allele (one on each X chromosome) to be colorblind.
- The mother of the colorblind girl in F₃ must be a carrier because:
- The girl inherited one recessive allele from her father (who is colorblind) and one from her mother.
- If the mother were colorblind, she would have two recessive alleles and would not be able to have a son with normal color vision (which she does).

3. Conclusion:
- The trait for colorblindness is recessive.
- The mother of the colorblind girl in F₃ is a carrier.
- Explanation: The mother must carry one recessive allele (to pass it to her daughter) but does not express the trait herself because she has one dominant allele as well.

#### Final Answer for Part C:
$$
\boxed{\text{Recessive, Carrier}}
$$

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Final Summary of Answers:

1. Part A: $\boxed{\text{Recessive}}$
2. Part B: $\boxed{\text{Dominant}}$
3. Part C: $\boxed{\text{Recessive, Carrier}}$