Answer:
Crossing over increases the genetic variation
Errors in crossover formation result in chromosomal rearrangements (duplications and deletions) and may also cause chromosome nondisjunction
Step-by-step explanation:
Crossing over, also known as recombination, refers to the exchange of genetic material (DNA) between non-sister chromatids of homologous chromosomes during meiosis. Crossing over increases the genetic variation of the resulting gametes, allowing different genetic combinations to be passed from parents to offspring. Unequal crossing over is a type of error associated with chromosomal duplication and/or deletion events. Unequal crossing over occurs when homologous sequences are not paired precisely. Moreover, errors in crossing over may also cause chromosome nondisjunction, thereby leading to aneuploidies.