Crossing over occurs when

sister chromatids are pulled apart at the centromere during anaphase II.

homologous chromosomes join together to form tetrads during prophase I.

chromosomes are grouped together into new nuclei during telophase II.

tetrads of homologous chromosomes randomly line up in metaphase I.

Question

Crossing over occurs when

 sister chromatids are pulled apart at the centromere during anaphase II.

 homologous chromosomes join together to form tetrads during prophase I.

 chromosomes are grouped together into new nuclei during telophase II.
 
 

 tetrads of homologous chromosomes randomly line up in metaphase I.

anonymous · Answer

do you know what crossing over is? If you don't, this has a good explanation: http://theagricos.com/genetics/crossing-over/

anonymous · Answer

Homologous chromosomes join together to form tetrads in Prophase I.