When crossing tomato plants with rounded fruits (A) and normal leaves (B) with plants with oblong fruits and spotted leaves, 350 plants with rounded fruits and normal leaves, 123 plants with oblong fruits and normal leaves, 119 plants with rounded fruits and spotty leaves; and 344 plants with oblong fruits and spotty leaves. Make a cross-breeding scheme, determine the genotypes of the offspring. Explain the formation of four phenotypic groups.
The scheme for solving the problem includes:
1) P AaBb × aabb
rounded fruit oblong fruits, normal leaves spotty leaves
G AB, AB, AB, ABAB
2) Genotypes and phenotypes of offspring:
350 plants with rounded fruits and normal leaves – AaBb
123 – with oblong fruits and normal leaves –aaBb
119 – with rounded fruits and spotted leaves –Aabb
344 – with oblong fruits and spotted leaves –aabb.
3) The presence in the offspring of two groups of individuals with dominant (350) and recessive (344) characters in approximately equal proportions is the result of the linked inheritance of dominant alleles among themselves and recessive alleles among themselves.
Two other phenotypic groups are formed by the fusion of gametes formed as a result of crossing over between allelic genes.
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.