00:01
In cattle, hornless is completely dominant over the horned condition.
00:05
A hornless bull is bred to two cows.
00:08
With cow a, which is horned, a hornless calf is produced.
00:11
With cow b, also horned, a horned calf is produced.
00:16
What are the genotypes of the bull and the two cows? so we know the bull is hornless.
00:22
It tells us right here.
00:24
Hornless is dominant.
00:26
In order for that dominant trait to show there has to be at least one.
00:30
Dominant allele.
00:33
However, based on the description that it's a hornless bull, we don't know if the other allele is recessive or dominant because either one is going to show that hornless trait.
00:45
So let's move on to the cows.
00:47
So cow a is horned.
00:50
Horned is recessive.
00:53
In order for that recessive trait to show both alleles have to be recessive.
00:58
Because if there's one dominant allele, that dominant trait is going to show.
01:03
So in order for the horned trait to show, the cow has to be homozygous recessive.
01:10
And then we move to cow b, who is also horned.
01:14
So same thing...