Question

In a certain breed of dogs, black hair is dominant and brown hair is recessive. If two parents are heterozygous for black hair, what is the probability that their offspring will be black?

(It`s not 50%, My second guess is 1/4?)

Answer 1

Since they're heterozygous, the both are Bb. When you cross that, you get one BB, two Bb, and one bb. Since black is dominant, 3 out of 4 of those options result in black hair. Therefore, 75% of offspring will have black hair.

Answer 2

Answer:

There is a 75% probability that their offspring will be black.

Explanation:

This breed of dogs is heterozygous for the Gene responsible for hair colour. This means that for this gene, one same dog has one allele that it is dominant Black hair (B), and one that its recessive brown hair (b). This dog has Black hair colour, but can still have offspring with brown hair colour, if mating with another heterozygous dog for this gene.

When you cross two dogs with heterozygous gene for hair colour, it will be represented as Bb x Bb. All the possible outcomes are BB-Bb-BB-bb, as they receive one gene from the mother and one from the father. Which means that 3 out of 4 dogs will have Black hair colour (dominant trait represented as B), equal to 75% of the population.