A pair of conjugated chromosomes forms a bivalent or tetrad. In the future, a crossover occurs between the bivalent chromosomes – this is a phenomenon of exchange of regions of homologous chromosomes. At each such point, which is called chiasm, two of the four chromatids cross. At the end of prophase, repulsive forces arise between conjugated chromosomes. The two homologues remain linked at the points where crossingover between the paternal and maternal chromatids occurred.
Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.