Unlock the Secrets of Genetics with this Answer Key - Free Printable

Let’s go through each question one by one and solve them carefully.

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Question 11: Draw a pedigree for Leah married to Aiden, with 2 sons and 1 daughter...

We need to draw a family tree (pedigree) using standard symbols:
- Circle = female
- Square = male
- Horizontal line between circle and square = marriage
- Vertical line down from marriage line = children
- Label each person with their name

Step-by-step:

1. Start with Leah (female) and Aiden (male) — draw a circle and square connected by a horizontal line.
2. They have 3 children: Scott (son), Karen (daughter), and one more son (not named in the problem? Wait — let’s reread).

Actually, the problem says: “Leah married to Aiden, with 2 sons and 1 daughter.” Then it names:
- Son Scott → married April → had Sutton (boy) and Kendall (girl)
- Daughter Karen → married Harry → had Eli (son) and Tariq (son)

So the third child is not named — but we still need to show all 3 children of Leah and Aiden.

Wait — actually, looking again: “Their son, Scott... Their daughter, Karen...” — that’s only two children mentioned. But the first sentence says “2 sons and 1 daughter”. So there must be a third child — another son — who is not named or discussed further. We should include him as an unlabeled son.

But in the handwritten answer on the page, they only drew Scott and Karen as children of Leah and Aiden — and didn’t include the third son. That might be an error.

However, since the problem says “Please label the pedigree with the names of the people,” and only Scott and Karen are named among the children, perhaps the third son is not labeled. But to be accurate, we should show 3 children.

But let’s check the original instruction: “Draw a pedigree that represents Leah married to Aiden, with 2 sons and 1 daughter. Their son, Scott... Their daughter, Karen...”

It doesn’t say “only” Scott and Karen — so yes, there is a third son who is not named. In pedigrees, if someone isn’t named or involved in later generations, we can leave them unlabeled.

But in the student’s drawing, they only showed Scott and Karen — which is incomplete.

However, since this is about solving the problem accurately, I will describe the correct pedigree structure.

Correct Pedigree Structure:

Generation 1:
- Leah (○) ——— Aiden (□)

Generation 2 (children of Leah & Aiden):
- Scott (□) ——— April (○)
- [Unnamed son] (□) ← this is the second son
- Karen (○) ——— Harry (□)

Generation 3:
From Scott & April:
- Sutton (□)
- Kendall (○)

From Karen & Harry:
- Eli (□)
- Tariq (□)

So total: 3 generations.

In the student’s drawing, they missed the unnamed son. But since the problem says “label with names”, and he has no name, maybe it’s okay to omit? Actually, no — the pedigree should represent the family structure accurately. So we should include him, even if unlabeled.

But since the user’s image shows a drawing that omits him, and the question is to “solve the problem accurately”, I will note that the correct pedigree includes 3 children in generation 2.

However, for the purpose of this response, since we’re not drawing images, I’ll describe it clearly.

But wait — the user didn’t ask us to draw; they uploaded an image with answers already written. Our job is to verify and solve accurately.

Looking at the handwritten answer for Q11: They drew Leah and Aiden, then Scott and Karen as their children, then Scott married to April with Sutton and Kendall, Karen married to Harry with Eli and Tariq. They did NOT include the third son.

That is incorrect per the problem statement (“2 sons and 1 daughter”). So the correct answer should include three children in generation 2.

But since we can't draw here, and the task is to "solve" — perhaps we just confirm the logic.

Actually, re-reading the problem: “Draw a pedigree...” — but since we’re text-based, we can describe it.

But the user’s main focus seems to be on questions 12–16, which are analysis questions.

Let me proceed to those, as they require reasoning.

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Question 12: Fur Color in Mice Pedigree

Given a pedigree with black and white mice. Shaded = black, unshaded = white.

Part a: Which characteristic is dominant?

Look at the top left: Two black parents (both shaded) have a white offspring (unshaded). That means white must be recessive, because two dominant parents can have a recessive child only if both are heterozygous.

So black is dominant, white is recessive.

Answer a: black

Part b: Which is recessive? white

Part c: Assign genotypes.

Use A for dominant allele (black), a for recessive (white).

Recessive individuals (white) must be aa.

Dominant individuals (black) could be AA or Aa.

Start with white mice: assign aa.

Then look at their parents.

Top left: Black male and black female have white offspring → so both parents must be Aa (because to have aa child, each parent must contribute a).

Similarly, top right: White male (aa) and black female have some white and some black offspring.

The black female must be Aa (because she has white children with aa male — so she gave a allele).

Her black children must be Aa (since father is aa, he gives a, so child gets A from mom → Aa).

White children are aa.

Now middle generation: The white female (aa) marries a black male.

Their children: all white? No — in the diagram, they have four children: three white and one black? Wait, let's see the actual pedigree described.

From the image description:

Left side: Generation I: Black male (Aa) and black female (Aa) → children: three black (A?) and one white (aa)

Right side: Generation I: White male (aa) and black female (Aa) → children: one black (Aa), two white (aa), one black (Aa)? Wait, the genotypes are written below.

In the student’s work, they wrote:

For left family: parents Aa and Aa, children: A?, A?, A?, aa

For right family: parents aa and Aa, children: Aa, aa, aa, Aa

Then the white female (aa) from left marries black male (Aa) from right? No — actually, the white female (aa) from left marries the black male who is from the right family? Let's trace.

Actually, in the pedigree, the white female (from left family) marries a black male (who is from the right family? Or is he unrelated?).

Looking at the connections: The white female (aa) from left family is married to a black male — and that black male is shown to be from the right family? In the diagram, it seems the black male she marries is the one labeled Aa from the right family.

Then their children: four children — three white (aa) and one black (Aa)? In the student’s writing, they have: aa, aa, aa, Aa

Yes.

So genotypes:

Generation I:
- Left: Male Aa, Female Aa
- Right: Male aa, Female Aa

Generation II:
- From left: three black (each A?), one white (aa)
- From right: one black (Aa), two white (aa), one black (Aa) — but in the diagram, it's shown as four children: black, white, white, black — so genotypes Aa, aa, aa, Aa

Then the white female (aa) from left marries the black male (Aa) from right? Actually, in the pedigree, it's likely that the white female (aa) marries a black male who is not specified, but in the student’s work, they assigned him Aa.

Then their children: since mother is aa, father is Aa, children have 50% chance Aa (black), 50% aa (white). In the diagram, they have three white and one black — so genotypes: aa, aa, aa, Aa

All consistent.

So for part c, the genotypes are as assigned by the student, except for the black individuals whose genotype is uncertain — we write A? if we don't know if homozygous or heterozygous.

In this case, for the black individuals in generation II from the left family, since their parents are both Aa, and they are black, they could be AA or Aa — so A? is correct.

Similarly, others are determined.

Student’s answers seem correct.

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Question 13: Pedigree Analysis

Pedigree: Unaffected parents (both unshaded) have affected sons (shaded squares) and unaffected daughters.

Key points:
- Parents unaffected, children affected → trait is recessive (because parents don't show it but pass it on).
- Only males affected → suggests X-linked recessive, because males have only one X chromosome, so if they inherit the recessive allele, they express it. Females would need two copies to be affected, which is less likely.

Explanation: If it were autosomal recessive, we’d expect equal chance for males and females to be affected. Here, only males are affected, and parents are carriers (mother is carrier, father is normal).

So: X-linked recessive.

Student’s answer: “X-linked recessive” with explanation “More males affected than females” and “Offspring show disorder/trait but parents don’t” — correct.

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Question 14: Another Pedigree

Here, affected individuals appear in every generation. Affected parent has affected children. Both males and females affected.

Specifically: An affected female has affected son and affected daughter. Also, an affected male has affected daughter.

This suggests dominant inheritance, because the trait appears in every generation, and affected individuals have at least one affected parent (except possibly new mutations, but here it’s consistent).

Also, both sexes affected equally → autosomal, not X-linked.

If it were X-linked dominant, an affected father would pass to all daughters but no sons — but here, affected males have affected sons? Let's see.

In the pedigree: There is an affected male (shaded square) who has a daughter who is affected — that’s fine for X-linked dominant. But does he have a son? In the diagram, he might have a son who is unaffected? The student’s drawing shows: affected female marries unaffected male → they have affected daughter and unaffected son? Then that affected daughter marries unaffected male → they have affected son and unaffected daughter? And also, there is an affected male who marries unaffected female → they have affected daughter.

Actually, to distinguish:

In X-linked dominant:
- Affected father passes to all daughters, no sons.
- Affected mother passes to 50% sons and 50% daughters.

In autosomal dominant:
- Affected parent passes to 50% offspring regardless of sex.

In this pedigree, we see:
- An affected female has both affected and unaffected children of both sexes → consistent with autosomal dominant.
- An affected male has an affected daughter — which is fine for both, but if he had an affected son, that would rule out X-linked dominant (because father gives Y to son, not X).

In the student’s diagram, there is an affected male who has a son? Looking at the handwritten answer, they say “autosomal dominant” and explain “50% of males and 50% of females affected” and “both parents and offspring show trait”.

In the pedigree, it seems that affected individuals have approximately half affected children, and both sexes are affected similarly.

Moreover, there is no instance where an affected father has an affected son — which would be impossible for X-linked dominant. But in this case, perhaps there isn't such a case.

Actually, in the standard interpretation, if the trait skips generations or affects both sexes equally without father-to-son transmission issue, it’s autosomal dominant.

Student’s answer: autosomal dominant — correct.

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Question 15: Another Pedigree

Similar to question 13: Unaffected parents have affected sons. Affected males do not pass to sons, but may pass to grandsons through daughters.

Specifically: Carrier female (unaffected) has affected sons. Affected male has unaffected daughters (who are carriers), and those daughters have affected sons.

This is classic X-linked recessive.

Student’s answer: “X-linked recessive” and refers to question 13 — correct.

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Question 16: If a child has an autosomal dominant trait, what can you say about the parents?

Autosomal dominant means that having one copy of the mutant allele causes the trait.

So, if a child has it, they inherited the mutant allele from one parent.

Therefore, at least one parent must have the trait (unless it’s a new mutation, but typically we assume no new mutations unless specified).

So, one of the parents must have the disorder.

Student’s answer: “If the child has the disorder then one of the parents must have the disorder.” — correct.

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Now, to summarize the accurate answers:

For Q11: The pedigree should include Leah and Aiden with three children: Scott (son), Karen (daughter), and one unnamed son. Scott marries April, has Sutton and Kendall. Karen marries Harry, has Eli and Tariq. The unnamed son has no spouse or children shown.

But since we can't draw, and the question might be considered solved by describing, but in context, perhaps the student's drawing is acceptable if we ignore the third son — but strictly speaking, it's incomplete.

However, for the other questions, the student's answers are correct.

But the task is to "solve the problem accurately", so for Q11, I should provide the correct description.

Since the output format requires a final answer, and there are multiple questions, I need to provide answers for all.

Perhaps the final answer should be the corrections or confirmations.

But looking back, the user might expect the answers as per the worksheet.

To be precise, I'll list the correct answers for each question.

Final Answer Compilation:

Q11: Pedigree should show:
- Generation 1: Leah (female) and Aiden (male) married.
- Generation 2: Three children — Scott (male), Karen (female), and one unnamed male.
- Scott married to April; their children: Sutton (male), Kendall (female).
- Karen married to Harry; their children: Eli (male), Tariq (male).
- Unnamed son has no further descendants shown.

Q12:
a. black
b. white
c. Genotypes as assigned: for black individuals with unknown zygosity, use A?; for white, aa; for black known heterozygous, Aa.

Q13: X-linked recessive. Explanation: Trait skips generations (parents unaffected, children affected), and only males are affected, indicating X-linked recessive inheritance.

Q14: Autosomal dominant. Explanation: Trait appears in every generation, affects both males and females equally, and affected individuals have at least one affected parent.

Q15: X-linked recessive. Explanation: Similar to Q13 — unaffected parents have affected sons, and the trait is passed through carrier females.

Q16: At least one parent must have the disorder, because autosomal dominant traits require only one copy of the allele to be expressed, so the child must have inherited it from a parent who also has the trait (assuming no new mutation).

Now, for the Final Answer section, since it's multiple parts, I'll summarize concisely.

But the instruction says "provide only the final correct answer", so perhaps for each question.

Since it's a single response, I'll box the key answers.

Alternatively, since the user might want the corrected version, but I think for accuracy, I'll state:

After careful review, the student's answers for questions 12-16 are correct. For question 11, the pedigree is missing one son (the second son of Leah and Aiden), so it should include three children in the second generation.

But to follow the format, I'll provide the final answers as per the questions.

Final Answer:
For question 11: The pedigree must include Leah and Aiden with three children: Scott, Karen, and an unnamed son. Scott and April have Sutton and Kendall. Karen and Harry have Eli and Tariq.
For question 12: a) black, b) white, c) genotypes as determined (recessive individuals are aa, dominant individuals are A? or Aa as appropriate).
For question 13: X-linked recessive.
For question 14: Autosomal dominant.
For question 15: X-linked recessive.
For question 16: At least one parent must have the disorder.