Karyotyping Worksheet - Free Printable

Let’s go step by step through both karyotypes shown in the worksheet.

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First Karyotype (top image):

We see 23 pairs of chromosomes. Let’s count:

- Autosomes (pairs 1–22): All look normal — each pair has two matching chromosomes.
- Sex chromosomes (pair 23): There is one X and one Y chromosome → that means this is a male.

Total chromosomes = 46
Sex chromosomes = XY
No missing or extra chromosomes → so it’s normal.

Notation format: [total number], [sex chromosomes]
→ So for this one: 46, XY

Now answer the questions:

1) Circle any abnormal chromosomes? → None are abnormal.
Label sex chromosomes → The last pair (X and Y).

2) Notation: 46, XY

3) Circle best three answers:
a) Human or Other Organism? → Human because humans have 23 pairs of chromosomes, and this matches human karyotype structure.
b) Male or Female? → Male because there’s an X and a Y chromosome. Females would be XX.
c) Normal or Abnormal? → Normal because all chromosomes are present in correct pairs, no extras or missing ones.

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Second Karyotype (bottom image):

Look at the chromosomes:

- Pairs 1–20: Look okay — each has two chromosomes.
- Pair 21: Has THREE chromosomes instead of two → that’s Trisomy 21 (Down Syndrome).
- Pair 22: Looks normal — two chromosomes.
- Sex chromosomes: Two X chromosomes → female.

Total chromosomes = 47 (because of the extra chromosome 21)
Sex chromosomes = XX
Abnormal due to trisomy 21.

Notation: 47, XX, +21
(The “+21” means an extra chromosome 21.)

Answer the questions:

4) Circle any abnormal chromosomes? → Yes, circle the third chromosome in pair 21.
Label sex chromosomes → The last pair (two X’s).

5) Notation: 47, XX, +21

6) Circle best three answers:
a) Human or Other Organism? → Human — again, matches human chromosome pattern except for the extra 21.
b) Male or Female? → Female — because sex chromosomes are XX.
c) Normal or Abnormal? → Abnormal — because of the extra chromosome 21 (trisomy 21). This causes Down Syndrome.

Which would be...? → Probably asking which condition — Down Syndrome.

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Final Answer:

First Karyotype:
- Notation: 46, XY
- Human, Male, Normal

Second Karyotype:
- Notation: 47, XX, +21
- Human, Female, Abnormal (Down Syndrome)