Let’s go step by step through the pedigree chart to answer each question. We’ll count shapes, lines, and generations carefully.
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Question 1: Number all individuals on the pedigree at the top of each shape.
We don’t need to write numbers here since it’s just instruction — but we’ll use numbering in our heads for counting.
Generation I:
- Individual 1 (square, clear)
- Individual 2 (circle, darkened)
Generation II:
- Individual 3 (circle, clear)
- Individual 4 (circle, clear)
- Individual 5 (square, clear) ← married to #4
Generation III:
- Individual 6 (square, clear) ← child of #3? Wait — let’s trace properly.
Actually, looking at the diagram:
From Generation I:
- Couple: #1 (male, normal) and #2 (female, hemophilia)
→ They have two daughters in Generation II: #3 and #4 (both circles, clear → normal females)
Then, #4 marries #5 (a male, square, clear → normal male)
They have three children in Generation III:
- #6: square, clear → normal male
- #7: circle, clear → normal female
- #8: square, darkened → male with hemophilia
Then, #8 (hemophiliac male) marries #9 (circle, clear → normal female)
They have seven children in Generation IV:
From left to right:
- #10: square, darkened → hemophiliac male
- #11: circle, clear → normal female
- #12: square, darkened → hemophiliac male
- #13: circle, darkened → hemophiliac female
- #14: square, clear → normal male
- #15: square, clear → normal male
- #16: circle, clear → normal female
So total individuals = 16. But we don’t need to list them unless asked — we’ll use this for counting.
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Question 2: In a pedigree, a square represents a male...
a. How many males are there?
Count all squares:
Gen I: #1 → 1
Gen II: #5 → 1
Gen III: #6, #8 → 2
Gen IV: #10, #12, #14, #15 → 4
Total males = 1 + 1 + 2 + 4 =
8
b. How many males have hemophilia?
Look for darkened squares:
Gen III: #8 → 1
Gen IV: #10, #12 → 2
Total = 1 + 2 =
3
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Question 3: A circle represents a female...
a. How many females are there?
Count all circles:
Gen I: #2 → 1
Gen II: #3, #4 → 2
Gen III: #7, #9 → 2
Gen IV: #11, #13, #16 → 3
Wait — Gen IV has 7 children: positions 1 to 7 from left:
#10 (M), #11 (F), #12 (M), #13 (F), #14 (M), #15 (M), #16 (F) → so 3 females in Gen IV
Total females:
Gen I: 1
Gen II: 2
Gen III: 2 (#7 and #9)
Gen IV: 3
→ 1+2+2+3 =
8
b. How many females have hemophilia?
Darkened circles:
Gen I: #2 → 1
Gen IV: #13 → 1
Total =
2
(Note: #9 is clear → normal; #3, #4, #7, #11, #16 are all clear → normal)
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Question 4: A marriage is shown by a horizontal line connecting a circle to a square.
How many marriages are there?
Look for horizontal lines between circle and square:
1. Gen I: #1 (square) — #2 (circle) → Marriage 1
2. Gen II: #4 (circle) — #5 (square) → Marriage 2
3. Gen III: #8 (square) — #9 (circle) → Marriage 3
That’s it. No other couples shown.
Answer:
3
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Question 5: A line perpendicular to a marriage line indicates offspring...
a. How many children did the first couple have?
First couple = Gen I: #1 and #2
Their children: look below their marriage line → connects to two circles in Gen II: #3 and #4
So →
2 children
b. How many children did the third couple have?
Third couple = Gen III: #8 and #9
Their children: Gen IV — 7 individuals (from #10 to #16)
Count: 7 children
Answer:
7
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Question 6: Level I represents the first generation...
a. How many generations are there?
Labeled as I, II, III, IV → that’s
4 generations
b. How many members are there in the fourth generation?
Gen IV: we counted 7 individuals (#10 to #16)
Answer:
7
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Final Answer:
2a. 8
2b. 3
3a. 8
3b. 2
4a. 3
5a. 2
5b. 7
6a. 4
6b. 7
Parent Tip: Review the logic above to help your child master the concept of pedigree worksheet interpreting a human pedigree.
