In cattle, coat color is determined by a single gene exhibiting complete dominance, where the allele for black coat () is dominant over the allele for red coat (). Match each monohybrid cross scenario with its correct genotypic or phenotypic outcome outcome/deduction.
- Cross between a heterozygous black bull () and a red cow ()Phenotypic ratio of black : red ( black, red)
- Cross between two heterozygous black cattle ()Genotypic ratio of yielding a phenotypic ratio
- Cross between a homozygous black bull () and a heterozygous black cow ()Genotypic ratio of with black phenotype
- Test cross of an individual with dominant phenotype producing black offspringDeduction that the tested black parent has a homozygous dominant () genotype
Answer
The monohybrid cross scenarios match their expected outcomes as follows: The cross between a heterozygous black bull and a red cow yields a phenotypic ratio of 1 black : 1 red; the cross between two heterozygous black cattle yields a genotypic ratio of 1 BB : 2 Bb : 1 bb; the cross between a homozygous black bull and a heterozygous black cow produces a genotypic ratio of 1 BB : 1 Bb (100% black); and a test cross producing 100% black offspring leads to the deduction that the tested parent is homozygous dominant (BB).
Each monohybrid inheritance scenario follows Mendel's First Law (Law of Segregation). Gametes segregate cleanly during meiosis, recombining in predictable frequencies: a heterozygous backcross () yields equal proportions of black and red progeny (); two heterozygotes () yield the classic genotypic ratio ( phenotype); a dominant homozygote crossed with a heterozygote () yields equal proportions of and ( black); and a test cross yielding zero recessive phenotypes confirms homozygosity of the dominant parent.
Step-by-Step Solution
Key Concept
Mendel's Law of Segregation and Monohybrid Genotypic/Phenotypic Ratios
Estimated Time:2m 0s