Question

What causes a change in the chromosome number of an organism?

A. mutation B. crossing over C. translocation D.non dysjunction

Answer 1

Answer-

D) Nondisjunction causes a change in the chromosome number of an organism.

Nondisjunction is an abberration of cell division in which chromosomes or chromatids that normally separate during anaphase remain together, resulting in daughter cells with too many or too few chromosomes.

Translocation is a kind of chromosomal rearrangement in which a block of genes from one linkage group is transferred to another linkage group. So, it involves changes in the arrangement of gene loci. Mutation is the changes in the nucleotide bases of chromosomes. Crossing over is defined as the recombination of linked genes brought about as a result of interchange of corresponding parts between the nonsister chromatids of a homologous chromosome. These three events do not cause a change in chromosome number. They are responsible for the changes in chromosome structure.