Genetics? 9th Grade Biology?
Question by ilufd17: Genetics? 9th Grade Biology?
The disease cystic fibrosis is caused by the recessive allele n.
1. What percentage of the children of a couple with genotypes NN and Nn will probably have cystic fibrosis?
2. What are the phenotypic and genotypic ratios for the offsprings of two people who both have the genotype Nn?
The top answer:
Answer by James W
1. 0%, because the child will always get a N from the NN parent.
2. Phenotypic ratio: 75% dominant, 25% recessive. Genotypic ratio: 25% NN, 50% Nn, 25% nn.
Do you know better? Why not leave your own answer in the comments below!
Tagged with: Biology • GENETICS • grade
Filed under: Cystic Fibrosis
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1. 0%. The possible choices of genotype of the child is NN, NN, NN and Nn, so the recessive will not be expressed.
2. Phenotype: 1 NN: 2 Nn: 1 nn
Genotype: 3 Normal : 1 Cystic Fibrosis
Learn to do Punnett squares. This stuff is easy.