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GATE 2025 BT – Question 53

Genetics, Cellular and Molecular Biology · Genetics: Mendelian inheritance, gene interaction, complementation, linkage, recombination, chromosome mapping, extrachromosomal inheritance · 2 marks · Multiple select

The blood group of the mother is A+ and that of the father is AB+. Which of the following statements is/are correct?

  1. Probability of the offspring with A+ blood group is 0.5
  2. Probability of the offspring with AB+ blood group is 0.125
  3. Probability of the offspring with B+ blood group is 0.125
  4. Probability of the offspring with O+ blood group is 0.375

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Show answer and explanation

Correct answer: (A) Probability of the offspring with A+ blood group is 0.5; (C) Probability of the offspring with B+ blood group is 0.125

Explanation

The published answer is A and C. The stated parental phenotypes do not fully specify ABO and Rh genotypes, so the exact probabilities cannot be derived uniquely without additional assumptions. For practice scoring follow the official A,C combination; the earlier explanation that only A could be correct did not resolve the missing-genotype issue.

Official GATE 2025 answer key: https://gate2026.iitg.ac.in/doc/download/2025_Key/BT_Keys.pdf