In the dihybrid cross, what fraction of the parents had black fur and black eyes? What about the offspring?
Answer (2)
The parents in the dihybrid cross had black fur and black eyes. The offspring display a phenotypic ratio that approximates the predicted ratio of 9:3:3:1.
Explanation
Analyze the problem and data We are given a table that shows the predicted and simulated fractions and percentages for a dihybrid cross experiment with black/white fur and black/red eyes. The question is incomplete and asks about the parents and offspring in the dihybrid cross, but it does not specify what information is needed. We need to fill in the blanks with appropriate information based on the context.
Analyze the predicted fractions Let's analyze the predicted fractions. The predicted fractions are 9/16, 3/16, 3/16, and 1/16. These fractions add up to 1, which is expected. In a typical dihybrid cross, the parents are heterozygous for both traits (e.g., BbEe, where B is black fur, b is white fur, E is black eyes, and e is red eyes). If both parents are BbEe, then the predicted phenotypic ratio of the offspring is 9:3:3:1. The 9/16 represents the double dominant phenotype (black fur and black eyes), 3/16 represents one dominant and one recessive (black fur and red eyes), 3/16 represents the other dominant and recessive (white fur and black eyes), and 1/16 represents the double recessive (white fur and red eyes).
Fill in the blanks Based on this analysis, we can fill in the blanks in the question.
Examples
Dihybrid crosses are used in genetics to predict the inheritance of two traits at the same time. For example, a farmer might use a dihybrid cross to predict the coat color and tail length of their livestock. By understanding the probabilities of different combinations of traits, the farmer can make informed decisions about breeding to achieve desired characteristics in their animals. The dihybrid cross helps in understanding the independent assortment of genes during gamete formation, which is a fundamental principle in genetics. The phenotypic ratio of 9:3:3:1 is a classic example of Mendelian inheritance.
Both parents in this dihybrid cross have black fur and black eyes, making the fraction of parents with this phenotype 100%. In their offspring, 9/16 will have black fur and black eyes, following the predicted phenotypic ratio. This shows how traits can be inherited independently in a dihybrid cross.
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