Okay, I need help.
"If short hair (L) is dominant to long hair (l), then what fraction of the offspring produced by a cross of Llxll will be homozygous dominant?
a) 1/2
b) 1/4
c) 1/3
d) none (no change of this offspring)
The key says that it's d, but when I do the punnet square, I come out with 50% Homozygous dominant. What am I doing wrong? Or is the key incorrect?
No, none will be LL, which is homozygous dominant. 50percent will be heterogous dominant (Ll)
I read it wrong, phew. Thank you!
To determine the fraction of offspring that will be homozygous dominant, we need to understand the principles of Mendelian inheritance.
In this scenario, "L" represents the allele for short hair (dominant), and "l" represents the allele for long hair (recessive).
When crossing two individuals with genotypes Llxll, we need to consider the possible combinations of alleles that can be passed down from each parent.
Let's create a Punnett square to visualize the possible combinations:
| L | l
--------|--------|--------
L | LL | Ll
--------|--------|--------
l | Ll | ll
From the Punnett square, we can see that there are four possible genotypes for the offspring: LL, Ll, Ll, and ll.
Out of these four genotypes, only one will be homozygous dominant (LL), while two will be heterozygous (Ll) and one will be homozygous recessive (ll).
Therefore, the correct answer is d) none - there is no fraction of the offspring that will be homozygous dominant.
To determine the fraction of offspring that will be homozygous dominant in a cross of Llxll, we need to understand the principles of Mendelian genetics and punnett squares.
When performing a punnett square, we need to consider the possible combinations of alleles from the two parent organisms. In this case, one parent has the genotype Ll and the other parent has the genotype ll.
When we set up the punnett square for this cross, we can determine the possible genotypes of the offspring by combining the alleles from each parent. In this case, the possible genotypes are Ll and ll.
The genotype Ll represents an individual with short hair (since L is dominant) but it is heterozygous (carries both the dominant and recessive alleles). The genotype ll represents an individual with long hair and is homozygous recessive.
Now, let's consider the question: "What fraction of the offspring produced by a cross of Llxll will be homozygous dominant?"
In this cross, none of the offspring will be homozygous dominant because a homozygous dominant genotype (LL) is not included in the possible genotypes resulting from this specific cross. Hence, the correct answer is option d) none.
If you obtained 50% homozygous dominant in the punnett square, it is possibly because you mistakenly assumed that the LL genotype was possible in this specific cross. However, based on the given information (short hair (L) being dominant to long hair (l)), the LL genotype is not part of the genotypes resulting from this specific cross.
Remember, when working with genetics, it is essential to carefully consider the given information and follow the rules of dominance and recessiveness to determine the correct genotypes and their frequencies.