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SAI International School
                                                   Subject- Biology
                                         Chapter- Heredity And Evolution
                  Subtopic- Mendel's Contribution (Dihybrid cross), How do traits get
                                         expressed?, Sex Determination
                                                       Module-24
                                                     Lesson Notes


               DIHYBRID CROSS:







































                     When two characters are considered while crossing two organisms, then such a
                       cross is known as a dihybrid cross.
                     In a dihybrid cross, the parents carry different pair of alleles for each trait. One
                       parent carries homozygous dominant allele, while the other one carries
                       homozygous recessive allele. The off springs produced after the crosses in the
                       F1 generation are all heterozygous for specific traits.
                     The ratio of characters, arising out of this cross, at F2 generation is called
                       dihybrid ratio.
                     E.g., If a plant with round and green pea is crossed with a plant with wrinkled and
                       yellow pea,
                     The first generation plants would all have round and green pea.


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