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SSC CGL 2023 PYQ — Question 41

SSC CGL - 20 July 2023 - Shift 4 • General Awareness • Q41

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In which year did an American cytogeneticist named Joe Hin Tjio publish a research finding that defined 2n=46 as the exact number of human chromosomes?

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Correct answer: C

Explanation

The correct answer is option 3 i.e. 1956.

  1. A seminal finding by American cytogeneticist Joe Hin Tjio in 1956 was the precise identification that a human cell normally has 46 chromosomes, or 2n=46. This discovery transformed the field of genetics and established a fundamental comprehension of human biology.
  2. Tjio's research, carried out in conjunction with Albert Levan, counted and analyzed human cell chromosomes using sophisticated microscopic techniques. There was some doubt about the exact number of chromosomes in humans before this discovery.
  3. Tjio's research paved the way for subsequent genetics studies and had a significant impact on subjects like evolutionary biology and medicine.