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An F1 hybrid (or filial 1 hybrid) is the first filial generation of offspring of distinctly different parental types. F1 hybrids are used in genetics, and in selective breeding, where it may appear as F1 crossbreed. The term is sometimes written with a subscript, as F1 hybrid.
â¦means of a backcross (or testcross); the F 1 hybrid (phenotype yellow round seed; genotype A a B b) is crossed to a double recessive plant (phenotype green wrinkled seed; genotype a a b b). If the hybrid gives four kinds of gametes in equal numbers and if all the gametes of the double recessive are alikeâ¦