Fragile x syndrome, characterized by mental r. e.t. a.r. d.a. t.i. o.n (spaced oot because filter), is caused by which chromosomal change?
a) deletion
b) translocation
c) inversion
d) insertion

Ans.

Fragile X syndrome is defined as a genetic disease, results in cognitive impairment and mental problems.

It is caused by a mutation in FMR1 gene that causes an increase in the CGG trinucleotide units in the gene. This is an example of insertion mutation as it involves addition of nucleotide sequences to the gene.

The FMR1 gene codes for a protein, which is necessary for normal cognitive functions and defect in this protein, due to mutated gene leads to development of disorder.

Thus, the correct answer is option D). 'insertion.'

correct answer is option a.

tropopause, stratopause and mesopause have all in common aspect that is point of maximum temperature in its layer of the atmosphere. all layers of atmosphere observe abrupt change in temperature. tropopause is the boundary between troposphere and stratosphere. stratopause is the boundary between stratosphere and mesosphere. mesopause is the boundary between mesosphere and thermosphere. these all boundaries are ranges between altitude of 0 to 80 km.