Question

There are many variations of Down syndrome with trisomy 21 accounting for close to 95% of all the cases recorded. There is another form of this syndrome which occurs when a segment of the 21st chromosome detaches to attach itself to another chromosome. The name of this form is___.
A. Relocation
B. Displacement
C. Transportation
D. Translocation

Answer 1

Hint:
Chromosomes are a pack of genes that determines the function and appearance of the body. Due to abnormal cell division, a person may have an extra chromosome which results in a genetic condition called Down syndrome. People with Down syndrome have developmental and intellectual problems. They have distinct facial features.

Complete step by step answer:
There are mainly three types of Down syndrome.
Trisomy 21: Most of the time, Down syndrome is caused by trisomy 21. In this case, the person has three copies of chromosome 21, instead of two copies, in all cells. This is due to the irregular division occurring in the developmental stages of the egg cell or sperm cell.
Mosaic Down syndrome: This is a rare form of Down syndrome, where few cells may contain an extra copy of ch21. Mosaic Down syndrome is the result of the irregular division of the cell after the process of fertilization.
Translocation Down syndrome: Down syndrome can also occur when a portion of chromosome 21 becomes translocated onto another chromosome, before or at conception. The offspring contain normal copies of ch21 along with an extra genetic material in the 21st chromosome attached to another chromosome.

Option ‘D’ is correct

Note:
Down syndrome is not inheritable in most cases. It occurs during the initial developmental stage of the fetus because of the error in cell division. Only translocation of Down syndrome is inherited from parents to offspring.