In a cross between a black and a white guinea pig, all members of the F₁ generation are black. The F₂ generation is made up of approximately 3/4 black and 1/4 white guinea pigs. Diagram this cross, showing the genotypes and phenotypes.

검증된 단계별 안내

Identify the type of inheritance pattern based on the phenotypic ratios in the F₂ generation. Since the F₁ generation is all black and the F₂ generation shows a 3:1 ratio of black to white, this suggests simple Mendelian inheritance with black being dominant over white.

Assign symbols to the alleles: let \( B \) represent the dominant black allele and \( b \) represent the recessive white allele.

Determine the genotypes of the parental (P) generation. Since crossing black and white guinea pigs produces all black F₁ offspring, the black parent is likely homozygous dominant (\( BB \)) and the white parent is homozygous recessive (\( bb \)).

Write the cross for the P generation: \( BB \times bb \). The F₁ offspring will all be heterozygous (\( Bb \)) and phenotypically black.

Set up the F₁ cross: \( Bb \times Bb \). Use a Punnett square to determine the F₂ genotypes: \( BB \), \( Bb \), and \( bb \). The expected genotypic ratio is 1:2:1, which corresponds to a phenotypic ratio of 3 black (\( BB \) and \( Bb \)) to 1 white (\( bb \)).

비슷한 문제에 대한 검증된 영상 답변:

이 영상 해법은 위 문제에 도움이 된다고 튜터들이 추천한 것입니다.

영상 길이:

주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Mendelian Inheritance

Mendelian inheritance refers to the principles of heredity established by Gregor Mendel, which include the concepts of dominant and recessive traits. In this case, the black coat color in guinea pigs is dominant over the white coat color, meaning that only one copy of the black allele is needed for the phenotype to be expressed.

Punnett Square

A Punnett square is a diagram used to predict the genotypes and phenotypes of offspring from a genetic cross. It organizes the possible combinations of alleles from the parents, allowing for a visual representation of inheritance patterns, such as the 3:1 ratio observed in the F₂ generation of this cross.

Genotype vs. Phenotype

Genotype refers to the genetic makeup of an organism, while phenotype is the observable physical or biochemical characteristics. In this scenario, the genotypes of the F₁ generation are heterozygous (Bb), resulting in a black phenotype, while the F₂ generation exhibits a phenotypic ratio of 3 black (BB or Bb) to 1 white (bb).