Genetic problem-monohybrid crosses with domimance.

If a brown eyed woman marries a blue eyed man and they have ten children, all brown eyed, can you be certain that the woman is homozygous? If the eleventh child has brown eyes, will that prove what the mother's genotype is?

This chart should give the answer to your eye color questions.

http://museum.thetech.org/ugenetics/eyeCalc/eyecalculator.html

To answer these questions, we need to understand the principles of inheritance and the patterns of genetic transmission in monohybrid crosses.

In this case, we are considering the eye color trait, where brown eye color (B) is dominant over blue eye color (b). In genetics, uppercase letters represent dominant alleles, and lowercase letters represent recessive alleles.

1. Can we be certain that the woman is homozygous?
Based on the information given, all ten of the couple's children have brown eyes, indicating that the brown eye color trait is consistently expressed. This suggests that one or both of the parents must have at least one dominant brown allele (B).

If the woman is homozygous (BB), meaning she has two dominant brown alleles, all her children would inherit one dominant allele from her and one recessive allele (bb) from the blue-eyed father. However, if she is heterozygous (Bb), with one dominant and one recessive allele, she would still have brown eyes but could pass on either the dominant or the recessive allele to her children.

Therefore, we cannot be certain that the woman is homozygous based on the information given.

2. Will the eleventh child's eye color determine the mother's genotype?
If the eleventh child has brown eyes, this alone cannot determine the mother's genotype. Brown eyes could result either from inheriting two dominant alleles (BB) if the mother is homozygous or from inheriting one dominant allele (B) if the mother is heterozygous (Bb).

To determine the mother's genotype definitively, a test cross would need to be performed. A test cross involves mating an individual with a dominant phenotype (brown eyes, in this case) but unknown genotype (either BB or Bb) with an individual who is homozygous recessive (bb). If any of the offspring have blue eyes, it would confirm that the mother is heterozygous (Bb), as the only way for an offspring to have the recessive blue eye allele (b) is if one parent passes it on.

In summary, without further testing, it is not possible to determine the mother's genotype based solely on the eye colors of her children.