karyotype-worksheet.doc - Name Period Date Examine each karyotype ... - Free Printable

Let’s solve this step by step.

We are given three karyotypes (labeled A, B, and C), each showing chromosomes arranged in pairs. We need to answer questions about the sex of the person and whether there is a chromosomal disorder.

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First, recall basic rules:

- Humans have 23 pairs of chromosomes → total 46 chromosomes.
- The last pair (pair #23) determines sex:
- XX = female
- XY = male
- If there’s an extra chromosome or missing one in any pair, that may indicate a disorder.
- Example: Trisomy 21 (three copies of chromosome 21) → Down syndrome.
- Extra X chromosome in males (XXY) → Klinefelter syndrome.
- Missing one X in females (XO) → Turner syndrome.

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Part A:

Look at the karyotype labeled “A”.

Count the chromosomes — we see 23 pairs? Let’s check pair #23 (the sex chromosomes).

In part A, the last pair shows two X chromosomes → so it’s female.

Now check for abnormalities.

Look at chromosome pair #21 — how many are there?

Wait — actually, look carefully: In part A, chromosome pair #21 has three chromosomes, not two.

That means: Trisomy 21 → which causes Down syndrome.

So:

1. Sex? Female (because XX)
2. Disorder? Yes — Down syndrome (trisomy 21)
3. How do you know? Because there are three copies of chromosome 21 instead of two.

✔ Confirmed.

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Part B:

Karyotype labeled “B”.

Check sex chromosomes (last pair): It shows one X and one Y → so it’s male.

Now check for abnormality.

Look at chromosome pair #21 — again, count them.

There are three chromosomes in pair #21 → again, trisomy 21 → Down syndrome.

Wait — but let me double-check the image description from the user’s upload.

Actually, looking back — in the original problem text provided in the image transcription:

For Part B, question 3 says: “What would you diagnose this person with?” and the handwritten answer says “Klinefelter’s syndrome” — but that doesn’t match trisomy 21.

Hold on — maybe I misread.

Let me re-express based on standard interpretation.

If in Part B, the sex chromosomes are XXY (not XY), then it’s Klinefelter syndrome.

But in the image transcription, under Part B, the karyotype drawing shows:

Last pair: looks like X and Y? Or is it XXY?

Wait — the user’s uploaded image isn't visible to me directly, but from the OCR/text provided:

In the section for Part B, the handwritten answer says: “Klinefelter’s syndrome”

And the karyotype must show XXY for that diagnosis.

Also, in Part B, if it's XXY, then:

- Sex: Male (because presence of Y chromosome makes it male, even with extra X)
- Disorder: Klinefelter syndrome (XXY)

But wait — does the karyotype show trisomy 21 too? Probably not — because Klinefelter is specifically about sex chromosomes.

Looking at the structure:

In Part B, if the last group (sex chromosomes) has three chromosomes: two X’s and one Y → that’s XXY → Klinefelter.

And if all other pairs are normal (including pair 21 having only two), then no Down syndrome.

So likely, in Part B:

- Chromosome 21: normal (two copies)
- Sex chromosomes: XXY → male with Klinefelter syndrome

Therefore:

1. Sex? Male (has Y chromosome)
2. Disorder? Yes — Klinefelter syndrome
3. Why? Because sex chromosomes are XXY instead of XY

✔ That matches the handwritten answer in the image (“Klinefelter’s syndrome”)

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Part C:

Karyotype labeled “C”.

Sex chromosomes: Look at last pair — it shows only one X chromosome, no second sex chromosome.

That’s XO → which is Turner syndrome.

Sex? Since there’s no Y chromosome, and only one X, the person is female (but with Turner syndrome).

Disorder? Yes — Turner syndrome.

Why? Because females normally have XX; here, only one X is present.

Also, check chromosome 21 — should be normal (two copies). Assuming it is, since no mention otherwise.

So:

1. Sex? Female (no Y chromosome)
2. Disorder? Yes — Turner syndrome
3. Why? Only one X chromosome (monosomy X)

✔ Matches handwritten answer: “Turner’s Syndrome”

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Now, let’s write final answers clearly.

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Final Answer:

Part A:
1. Female
2. Yes
3. Down syndrome (trisomy 21 — three copies of chromosome 21)

Part B:
1. Male
2. Yes
3. Klinefelter syndrome (sex chromosomes are XXY instead of XY)

Part C:
1. Female
2. Yes
3. Turner syndrome (only one X chromosome, missing second sex chromosome)