Dominant/recessive alleles, hertitary problem. :)?

Assume that hair color in humans is determined by a single gene as follows: B/B individuals have black hair; B/b have brown hair; and b/b have blonde hair.

Now here's the actual question:

If two brown hair people marry, what is the probability that their first child will have brown hair?

Dominant/recessive alleles, hertitary problem. :)?

B/b x B/b

1/4 BB black

2/4 B/b brown

1/4 bb blonde

50% chance of having brown hair

Unless you are specifically asked probability of having 2 consecutive kids with

black hair, you treat each birth independently. The probability of the next child having black hair is still 1/4 or 25%

Dominant/recessive alleles, hertitary problem. :)?

Bb + Bb

You can get BB (Black) Bb (brown) bB (brown) or bb (blonde. So, 50% chance of brown hair.

Dominant/recessive alleles, hertitary problem. :)?

Bb x Bb would produce 1 BB (black hair), 2 Bb (brown hair), and 1 bb (blond hair)

So if 2 brown haired people had kids, there's a 50% chance their child has brown hair. Every childbirth is a new situation, so results are independent of any previous birth....

Dominant/recessive alleles, hertitary problem. :)?

thats not how it works, your assuming brown hair is a case of codominance between black and blonde hair.

And even if that was the case, there would be several variables, you would have to know whether the parents were carriers or pure brown hairs, and i repeat, BROWN HAIR does NOT equal mix of blonde and black.

however, if a person has brown hair, they wont be carriers of black hair seeing as the gene for black hair is the most dominant,k they might be carriers of blonde hair, and the only time 2 brown haired people could produce a blonde haired child is if they are both carriers of blonde hair, and even then, it will only be a 25% chance (1 in 4)