Question

Схрестили довговухих овець із безвухим ( рецесивна ознака) бараном. У першому поколінні всі ягнята були коротковухими. Визначте генотипи батьків. Яких ягнят і в якому співвідношенні можна очікувати у другому поколінні?

Answer 1

А- ген довгих вух 
а ген безвухості 
Генотипи батьків 
Батько аа
Матір АА

АА*аа
Діти1 Аа коротковухі

У другому поуолінні 
Аа*Аа
Діти 2 АА,Аа,Аа,аа
Генотип 1:2:1
Фенотип1:2:1
аа-безвухі,
Аа-короковухі
АА-довговухі

Answer 2

Introduction:

In this scenario, long-eared sheep were crossed with a short-eared ram, where the short-eared trait is recessive. All the lambs in the first generation were short-eared. The goal is to determine the genotypes of the parents and predict the types of lambs and their ratios in the second generation.

Genotypes of the Parents:

To determine the genotypes of the parents, we need to understand the inheritance pattern of the ear length trait. In this case, the short-eared trait is recessive, which means that an individual must have two copies of the short-eared allele to exhibit the trait. The long-eared trait is dominant, so an individual only needs one copy of the long-eared allele to have long ears.

Since all the lambs in the first generation were short-eared, it means that both parents must have been heterozygous for the ear length trait. This means that they carried one copy of the short-eared allele and one copy of the long-eared allele. The genotypes of the parents can be represented as follows:

- Long-eared sheep: Ll - Short-eared ram: ll

Possible Lambs in the Second Generation:

Now that we know the genotypes of the parents, we can predict the types of lambs and their ratios in the second generation. The genotypes of the parents are as follows:

- Long-eared sheep: Ll - Short-eared ram: ll

When these parents are crossed, the possible genotypes and phenotypes of the lambs can be determined using a Punnett square. Here is a simplified representation of the Punnett square:

         | l       l
---------------------
L   | Ll      Ll
---------------------
l   | ll       ll

From the Punnett square, we can see that there are two possible genotypes for the lambs: Ll and ll. The lambs with the genotype Ll will have long ears, while the lambs with the genotype ll will have short ears.

The ratio of the lambs with long ears to those with short ears can be determined by counting the number of squares with each genotype. In this case, there are two squares with the genotype Ll and two squares with the genotype ll, so the ratio is 1:1.

Therefore, in the second generation, we can expect to see lambs with both long ears and short ears in a 1:1 ratio.

Conclusion:

In summary, when long-eared sheep (genotype Ll) are crossed with a short-eared ram (genotype ll), all the lambs in the first generation will be short-eared. The genotypes of the parents are Ll and ll. In the second generation, we can expect to see lambs with both long ears (genotype Ll) and short ears (genotype ll) in a 1:1 ratio.