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Science — CBSE Class 10 board question

Q1. [1]
When a human egg is fertilized by a sperm having 'Y' chromosome, the zygote has the following combination of chromosomes :
  1. (A) 44 + XX
  2. (B) 22 + XX
  3. (C) 44 + XY
  4. (D) 22 + XY
Previously asked in CBSE board exam
2026 31/5/1 Q5
Generated by claude-sonnet-4-6 · 2026-06-15 06:51 · grounding rag
Model Answer

(C) 44 + XY

When the egg (22 + X) is fertilized by a sperm carrying Y chromosome (22 + Y), the zygote formed has 44 + XY chromosomes, developing into a male child.

Explanation

The human egg always carries an X chromosome along with 22 autosomes (total 23). A sperm carrying Y has 22 + Y. On fertilization: (22 + X) + (22 + Y) = 44 + XY. Remember, sex is determined by the father's sperm, not the mother's egg.

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