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?

Correct option is C

The correct answer is (C) 1956.

• In 1956, an American cytogeneticist named Joe Hin Tjio published his groundbreaking research that identified 2n=46 as the exact number of human chromosomes.
• This discovery was significant because it corrected the previously believed number of 48 chromosomes, which had been mistakenly accepted for several years.
• Joe Hin Tjio's work laid the foundation for modern human cytogenetics and had a profound impact on the fields of genetics, biology, and medicine.

Information Booster:

Chromosomes:

• Chromosomes are thread-like structures located within the nucleus of animal and plant cells.
• Each chromosome is made of protein and a single molecule of deoxyribonucleic acid (DNA), which contains the organism's genetic information.
• Humans have 23 pairs of chromosomes, for a total of 46 chromosomes (2n=46).
• The 23rd pair of chromosomes determines the sex of the individual: XX for females and XY for males.
• Chromosomal abnormalities, such as Down syndrome, result from having an extra chromosome (trisomy 21) or other numerical or structural chromosomal changes.
• Chromosomes play a critical role in cell division, genetic diversity, and the inheritance of traits from one generation to the next.