00:01
So we're looking at some cattle.
00:03
We have a bowl, and we're using capital p means hornless, and little p means horns.
00:13
And we have a hornless bowl.
00:16
So we know here's at least one capital p.
00:20
And we're crossing him with three separate cows.
00:23
So let's have a look.
00:24
First of all, a cow is horned, so that's the p -not -p, crossed with our bowl, and the calf is also horned.
00:31
So we know they are also.
00:32
They have both recessive.
00:36
B, a horns, so the cow is hornless.
00:42
Crossed with our hornless bowl, we get a horned calf.
00:46
C, the cow has horns.
00:49
Crossed with our bull, we get a hornless calf.
00:58
Okay, so we need the genotypes and we need the ratios of the three matings.
01:04
So all i've done so far is fill in the two recessive allules if they are horns, because that's the recessive phenotype, and one with a question mark if they are hornless.
01:16
So, first of all, look at cross a.
01:21
The offspring have two recessive allials.
01:24
One would be from the cow, the other must be from our bull.
01:27
So our bull is a heterozygotes.
01:30
And cow a, we know, is a gulp -p...