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9.2.2.2. Mendel's second law or principle of segregation

Mendel's second law

When two heterozygous individuals of the first generation (F1) are crossed with each other, the recessive traits that did not appear in F1 reappear in F2 in a ratio of 3:1.

In F1 individuals, of the two different alleles for seed color, only one is manifested. When the heterozygous yellow individual (Aa) forms the gametes, the alleles are separated and each gamete only contains one of them.

During gamete production, meiosis occurs, so each gamete contains a unique allele for each gene. With fertilization, variation is ensured. For each trait, an organism inherits two alleles, one from each parent. This means that in somatic cells, one allele comes from the mother and one from the father. These can be homozygous or heterozygous.

That is to say: 

Questions that have come out in University entrance exams (Selectividad, EBAU, EvAU)

Genetics problems solved: Genetics  problems of Mendel's second law  (4th ESO). It contains genetic problems that have come out in EvAU exams from different Universities.