Spot the correct spelling of a chromosomal "three copies" term.

Question

Spot the correct spelling of a chromosomal "three copies" term.

1. A. Trisomie
2. B. Trissomy
3. C. Trisomy (Correct answer)
4. D. Trissomie

Correct Answer

Option C — Trisomy

Detailed Solution & Explanation

The correct answer is Trisomy.

Key Points

• Trisomy is the condition of having three copies of a chromosome instead of the usual two.
• The spelling follows its parts: tri- (three) + -somy, from Greek *soma*, "body" — one s, and the ending -somy, not "-somie".
• The best-known example is Trisomy 21, or Down syndrome, where chromosome 21 is present in triplicate.
• The distractors double the s (Trissomy, Trissomie) or use a French-looking "-ie" ending, neither of which occurs in the medical term.
• Compare monosomy (one copy) and polysomy (many), which follow the same pattern.

Additional Information

• Spelling questions favour scientific and medical terms, where the Greek or Latin parts fix the correct form: tri- (three), mono- (one), poly- (many) and *soma* (body).
• Related terms: monosomy (one copy), polysomy (many), aneuploidy (an abnormal chromosome number) and karyotype (the full chromosome set).
• Humans have 46 chromosomes in 23 pairs; Down syndrome is trisomy of chromosome 21, the commonest surviving autosomal trisomy.