Question

I need some help with my biology homework. I don't understand this dominant and receive gene stuff.

Answer 1

Okay so a dominant gene is a gene that will always be expressed within an offspring if it is present, a recessive gene requires to alleles to be shown within an offspring.

So.. for 9

A heterozygous black dog mates with a yellow dog

If something it heterozygous and exhibits the black trait or color then it must mean that black was dominant because if black was recessive then it require two alleles to "code" for it so...

B --> black

b --> yellow

So the genotype of the black dog must be Bb

and the genotype of the yellow dog is bb

Hopefully this makes sense, but let me know if you need help with any other questions.

If I did a punnet square to check

Bb x bb

       b          b

B    Bb       Bb

b    bb       bb

So half of the puppies are yellow and the other half are black.