Based on your history, you are probably talking about colorblindness, which is a disease inherited on the X chromosome. When it is passed on to a boy, the recessive allele shows itself because boys only have one X chromosome.
Edited answer:
Though recessive alleles do not express but if it adds to a deficiecy it is reflected in the boy, because only one X chromosome in present there, the other being Y chomosome which is almost enert.
If a boy is born with attached earlobes, he must have inherited two recessive alleles (ee), one from each parent. This means that both parents must either be carriers of the recessive allele (Ee) or express the attached earlobe phenotype themselves (ee). Therefore, at least one of the parents must have the recessive allele for attached earlobes.
This is because males have one X chromosome while females have two. Example: Say a mother is homozygous for a certain recessive X-linked trait (ie x*x*) while the father does not have this x-linked trait (XY) If they have one boy and one girl: The girl will receive an x chromosome from each parent, and will be x*x: this means she will be a carrier only, and will not display this recessive trait. The boy will receive an x chromosome from his mom and a y chromosome from his dad, so he will have to be x*y. The boy will always display the trait. It works similarly if the mother is a carrier(ie x*x): the boy is more likely to display the trait because he gets only one x chromosome.
well actually i very much disagree, i believe that color blindness is a sex-linked trait; therefore, a girl (written Xc ) who receives one recessive allele for one red-green blindness WILL NOThave the trait, however a boy who receives one recessive WILL be recessive.
The genotype of an ALD (adrenoleukodystrophy) boy is typically X-linked recessive. This means that the boy has a mutation on the X chromosome, which is responsible for the development of the disease. Typically, the genotype is represented as XL for an affected boy.
If a boy inherits an autosomal recessive disease, he would have inherited one copy of the mutated gene from each of his parents. The mother is a carrier, meaning she has one copy of the mutated gene but does not show symptoms of the disease. When both parents are carriers, there is a 25% chance with each pregnancy that the child will inherit two copies of the mutated gene and have the disease.
If a boy is born with attached earlobes, he must have inherited two recessive alleles (ee), one from each parent. This means that both parents must either be carriers of the recessive allele (Ee) or express the attached earlobe phenotype themselves (ee). Therefore, at least one of the parents must have the recessive allele for attached earlobes.
He has a homozygous genotype
He has at least one E allele is correct. I take the quiz
If a boy is born with detached earlobes, both of his parents must have detached earlobes as well, as this trait is inherited. Detached earlobes are a recessive trait, meaning that both parents must pass on the gene for detached earlobes in order for the child to have them.
He has at least ONE E allele
This is because males have one X chromosome while females have two. Example: Say a mother is homozygous for a certain recessive X-linked trait (ie x*x*) while the father does not have this x-linked trait (XY) If they have one boy and one girl: The girl will receive an x chromosome from each parent, and will be x*x: this means she will be a carrier only, and will not display this recessive trait. The boy will receive an x chromosome from his mom and a y chromosome from his dad, so he will have to be x*y. The boy will always display the trait. It works similarly if the mother is a carrier(ie x*x): the boy is more likely to display the trait because he gets only one x chromosome.
It was said earlier that, "Unattached earlobes are the dominant trait, twice as many people have unattached earlobes compared to attached." There is not actually any real proof that unattached earlobes are dominant. While more people may have unattached earlobes, attached earlobes are dominant. This was proved in a pedigree which covered three generations of extended families.
well actually i very much disagree, i believe that color blindness is a sex-linked trait; therefore, a girl (written Xc ) who receives one recessive allele for one red-green blindness WILL NOThave the trait, however a boy who receives one recessive WILL be recessive.
A recessive trait shows up when there is no dominant trait to mask it. For example, say the allele for brown hair is B and for red hair is b. If the father contributes an allele for brown hair and the mother contributes and allele for red hair, the child's phenotype would be Bb and it would have brown hair. However if both parents contributed an allele for red hair, the child's phenotype would be bb and it would have red hair. You can do the same thing for eye color. Say the allele for green eyes is G and the allele for blue eyes is g (I don't know if this is actually correct, but it's just an example). If the father gives the allele for green eyes, G, and the mother gives the allele for blue eyes, g, the child's phenotype is Gg and it has green eyes. However, if both parents contribute alleles for blue eyes, then the child's phenotype is gg and it has blue eyes.
A Boy and a girl have sex
Nothing
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