A1 the allele for tall pea plants is dominant over the...

a)1 The allele for tall pea plants is dominant over the allele for short pea plants. If two heterozygous plants are crossed, what will the genotypic and phenotypic ratios be? b)2 Purple flowers are dominant over white flowers, and green pods are dominant over yellow pods in pea plants. What would the probability be of producing a pea plant with white flowers and yellow pods from parent plants that are heterozygous for each trait? c)3 Red eyes are dominant on fruit flies but an x-linked recessive allele will produce white-eyed flies. If a pure breeding red-eyed female mates with a white-eyed male, what is the probability of white eyes in the F1 generation?

Transcript

00:01 The allele for tall pea plants is dominant over the allele for short pea plants.

00:06 If two heterozygous plants are crossed, what will the genotype and phenotype ratios be? so we're going to do our opponent square.

00:15 Both parents are heterozygous.

00:18 They're going to have one dominant and one recessive.

00:23 Go ahead and finish out the square.

00:30 So the genotype ratio, you've got one.

00:37 Homozygous dominant, two heterozygous, and one homozygous recessive.

00:43 So that's going to be a one to two to one ratio.

00:48 And then the phenotype ratio, you've got three that have at least one dominant allele, so they are going to be tall.

00:59 And you've got one that is homozygous recessive, so it'll be short.

01:04 So that is a three to one ratio.

01:08 And then, then looking at the next question b, purple flowers are dominant over white flowers and green pods are dominant over yellow pods in pea plants.

01:19 What would the probability be of producing a pea plant with white flowers and yellow pods from parent plants that are heterozygous for each trait? so if they're heterozygous for each trait, this will be the genotype of both parents.

01:38 I went ahead and completed the punnett square kind of time consuming.

01:47 And we are looking for the probability of producing a pea plant with white flowers, white flowers and yellow pods.

01:57 So in order for, so the white flowers are recessive.

02:02 So they need to have a homozygous recessive for white flowers.

02:08 And then the yellow pods are also recessive.

02:13 So their genotype needs to be completely homozygous recessive.

02:21 So looking at our puntit square, we can go through and look at all of our genotypes.

02:30 And the only one fits this genotype here is this one right there...