객관식
In a monohybrid cross, what is a Punnett square used to determine?
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2. Mendel's Laws of Inheritance
Monohybrid Cross
객관식
A black and white rabbit were mated. All F1 offspring were black, and the F2 offspring is made up of approximately ¾ black and ¼ white rabbits.
• Draw out two Punnet squares detailing both matings.
• Supposed two white F2 offspring were mated. What would be the phenotype and genotype of the F3 offspring?
A
White, aa
B
White, Aa
C
Black, Aa
D
Black AA
검증된 단계별 안내1
Step 1: Identify the genotypes of the parent rabbits. The black rabbit is likely homozygous dominant (BB) or heterozygous (Bb), while the white rabbit is homozygous recessive (bb). Since all F1 offspring are black, the black parent must be heterozygous (Bb).
Step 2: Draw the Punnett square for the F1 generation. Cross the heterozygous black rabbit (Bb) with the homozygous recessive white rabbit (bb). The possible genotypes for the F1 offspring are Bb and bb, but since all F1 are black, Bb is the dominant phenotype.
Step 3: Draw the Punnett square for the F2 generation. Cross two F1 heterozygous black rabbits (Bb x Bb). The possible genotypes are BB, Bb, and bb. The phenotypic ratio is 3 black (BB and Bb) to 1 white (bb).
Step 4: Consider the mating of two white F2 offspring. Since they are both white, their genotype must be homozygous recessive (bb). When two bb rabbits are mated, all F3 offspring will be white with the genotype bb.
Step 5: Review the possible genotypes and phenotypes for the F3 generation. Since the F3 offspring are from two white (bb) parents, they will all be white with the genotype bb. This confirms the phenotype and genotype of the F3 offspring as white, bb.
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