Here is the complete solution and explanation for the
Karyotype Worksheet based on the image provided.
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1. Look at the karyotype to the right
> *(This refers to the top-right karyotype showing chromosomes 1–22 + XY)*
a. Circle the Autosomal chromosomes
✔ Answer: All chromosomes
except the last pair (XY). So, circle chromosomes
1 through 22.
> *Autosomes are chromosomes 1–22 — they are not sex chromosomes.*
b. Put a box around the Sex chromosomes
✔ Answer: Box the
XY pair at the bottom right.
> *Sex chromosomes determine biological sex: XX = female, XY = male.*
c. Is this person male or female?
✔ Answer:
Male
> *Because the sex chromosomes are XY.*
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2. How many total chromosomes does a normal person have?
✔ Circle: 46
> *Humans have 23 pairs of chromosomes = 46 total (22 autosome pairs + 1 sex chromosome pair).*
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3. Put a star on a homologous pair
✔ Answer: Any pair of chromosomes that look identical in size and banding pattern — for example,
chromosome pair #1, or #5, or #10.
> *Homologous chromosomes are matching pairs — one inherited from each parent. They are similar in shape, size, and gene loci.*
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4. Look at the karyotype to the right. Do you see any chromosomal abnormalities? YES or NO
✔ Answer: YES
> *The karyotype shows an extra chromosome 21 — there are THREE copies instead of two → Trisomy 21.*
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5. Put a circle around the abnormal chromosomes
✔ Answer: Circle
all three chromosomes labeled #21 (in the bottom row).
> *Trisomy 21 means there are 3 copies of chromosome 21 instead of the normal 2.*
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6. Using the key below for chromosomal diseases, identify the disease this person has
✔ Answer: Down’s Syndrome
> *From the key: “Trisomy 21 → Down’s Syndrome”*
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7. Is this person male or female?
✔ Answer: Male
> *The sex chromosomes are XY — visible in the karyotype.*
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8. Look at the karyotype to the left. Is it MALE or FEMALE?
✔ Answer: FEMALE
> *The karyotype on the left ends with
XX — the sex chromosomes for females.*
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9. Using the key below, what disease does the karyotype above have?
✔ Answer: Turner’s Syndrome
> *The karyotype on the left has only
one X chromosome and no second sex chromosome → represented as “X” in the key → Turner’s Syndrome.*
> *Note: The karyotype shows 45 chromosomes total — missing one sex chromosome. This is characteristic of Turner’s Syndrome (45,X).*
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10. Which chromosome is the longest and has the most genes? 1 or 21
✔ Answer: 1
> *Chromosome 1 is the largest human chromosome and contains the most genes (~2,000–3,000). Chromosome 21 is one of the smallest.*
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11. Which chromosome is the shortest and has the fewest genes? 2 or 22
✔ Answer: 22
> *Chromosome 22 is shorter than chromosome 2 and has fewer genes. (Chromosome 21 is actually the shortest, but since 21 isn’t an option here, 22 is the correct choice among given options.)*
> *Clarification: In reality, chromosome 21 is the shortest, but if forced to choose between 2 and 22 — 22 is shorter and has fewer genes than chromosome 2.*
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12. In a normal karyotype how many autosomal chromosomes are there?
✔ Answer: 44
> *There are 22 pairs of autosomes → 22 × 2 = 44 autosomal chromosomes.*
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13. In a normal karyotype how many sex chromosomes are there?
✔ Answer: 2
> *One pair — either XX (female) or XY (male) — so always 2 sex chromosomes.*
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14. One type of chromosomal mutation is trisomy 21. What is another name for it?
✔ Answer: Down’s Syndrome
> *As shown in the key: “Trisomy 21 → Down’s Syndrome”*
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✔ Final Summary Answers:
1. a. Circle chromosomes 1–22
b. Box XY
c. Male
2. Circle
46
3. Star any homologous pair (e.g., pair #1)
4.
YES
5. Circle all three chromosome 21s
6.
Down’s Syndrome
7.
Male
8.
FEMALE
9.
Turner’s Syndrome
10.
1
11.
22
12.
44
13.
2
14.
Down’s Syndrome
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Let me know if you’d like a printable version or visual annotations!
Parent Tip: Review the logic above to help your child master the concept of karyotypes worksheet.
