Pedigree worksheet answers | Worksheetzone - Free Printable

Problem Analysis and Solution

The provided document contains two pedigree charts, each with associated questions. Let's solve the problems step by step.

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#### Pedigree Chart 1: Hemophilia

##### Key Rules for Pedigree 1:
- Squares represent males.
- Circles represent females.
- Darkened symbols indicate individuals with hemophilia.
- Clear symbols indicate individuals without hemophilia.

##### Questions and Solutions:

1. In a pedigree, a square represents a male. If it is darkened, he has hemophilia; if clear, he had normal blood clotting.
- a. How many males are there?
- Count all squares in the pedigree.
- Total males: 8 (I-1, II-3, II-4, III-1, III-5, IV-1, IV-3, IV-6).
- Answer: 8
- b. How many males have hemophilia?
- Count darkened squares.
- Males with hemophilia: III-5, IV-1, IV-3.
- Answer: 3

2. A circle represents a female. If it is darkened, she has hemophilia; if open, she is normal.
- a. How many females are there?
- Count all circles in the pedigree.
- Total females: 8 (I-2, II-2, II-5, III-2, III-4, IV-2, IV-4, IV-7).
- Answer: 8
- b. How many females have hemophilia?
- Count darkened circles.
- Females with hemophilia: III-4, IV-4.
- Answer: 2

3. A marriage is indicated by a horizontal line connecting a circle to a square.
- a. How many marriages are there?
- Count all horizontal lines connecting a square and a circle.
- Marriages: I-1 ↔ I-2, II-3 ↔ II-4, III-1 ↔ III-2.
- Answer: 3

4. A line perpendicular to a marriage line indicates offspring. If the line ends with either a circle or a square, the couple had only one child. However, if the line is connected to another horizontal line, then several children were produced, each indicated by a short vertical line connected to the horizontal line. The first child born appears to the left and the last born to the right.
- a. How many children did the first couple (couple in row I) have?
- The first couple is I-1 and I-2.
- They have two children: II-3 and II-4.
- Answer: 2
- b. How many children did the third couple (couple in row III) have?
- The third couple is III-1 and III-2.
- They have seven children: IV-1, IV-2, IV-3, IV-4, IV-5, IV-6, IV-7.
- Answer: 7

5. Level I represents the first generation, level II represents the second generation.
- a. How many generations are there?
- Count the levels in the pedigree.
- Generations: I, II, III, IV.
- Answer: 4
- b. How many members are there in the fourth generation?
- Count all individuals in level IV.
- Members in IV: IV-1, IV-2, IV-3, IV-4, IV-5, IV-6, IV-7.
- Answer: 7

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#### Pedigree Chart 2: Huntington's Disease

##### Key Rules for Pedigree 2:
- Shaded symbols indicate individuals with Huntington's Disease.
- Genotypes are provided for some individuals.
- Individuals are numbered by generation and order of birth (e.g., II-2 is the second individual in the second generation).

##### Questions and Solutions:

6. Write the generation on the pedigree numbers (roman numerals).
- This question asks you to label each individual with their generation number.
- Answer:
- I-1, I-2
- II-1, II-2, II-3, II-4, II-5, II-6, II-7
- III-1, III-2, III-3

7. Which members of the family above are afflicted with Huntington's Disease?
- Identify shaded symbols.
- Afflicted individuals: I-1, II-2, II-3, II-7, III-3.
- Answer: I-1, II-2, II-3, II-7, III-3

8. There are no carriers for Huntington's Disease—you either have it or you don’t. With this in mind, is Huntington’s disease caused by a dominant or recessive trait?
- Since there are no carriers and the disease is present in individuals who have at least one affected parent, it must be a dominant trait.
- Answer: Dominant

9. How many children did individuals I-1 and I-2 have?
- Count the number of children of the first couple (I-1 and I-2).
- Children: II-1, II-2, II-3, II-4, II-5, II-6, II-7.
- Answer: 6

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Final Answers:

1. Pedigree 1:
- a. 8 males
- b. 3 males with hemophilia
- a. 8 females
- b. 2 females with hemophilia
- a. 3 marriages
- a. 2 children for the first couple
- b. 7 children for the third couple
- a. 4 generations
- b. 7 members in the fourth generation

2. Pedigree 2:
- 6. Generations labeled as shown.
- 7. Afflicted individuals: I-1, II-2, II-3, II-7, III-3
- 8. Dominant trait
- 9. 6 children for I-1 and I-2

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Final Boxed Answers:
1. Pedigree 1:
- a. 8
- b. 3
- a. 8
- b. 2
- a. 3
- a. 2
- b. 7
- a. 4
- b. 7

2. Pedigree 2:
- 7. I-1, II-2, II-3, II-7, III-3
- 8. Dominant
- 9. 6

\boxed{8, 3, 8, 2, 3, 2, 7, 4, 7, I-1, II-2, II-3, II-7, III-3, Dominant, 6}