On an extraterrestrial planet, which had organisms that reproduced with DNA the same way that organisms on Earth do, green little organisms have eyes that are triangular or round shaped. Triangular eyes are dominant to round eyes. A cross was performed between two of these extraterrestrials with the genotypes IT and tt. Predict the probability that an offspring would have round eyes.
2:4
1:4
4:4
0:4
To determine the probability of an offspring having round eyes, we need to consider the genotype of the parents.
The first parent has the genotype "IT" and the second parent has the genotype "tt". Since the trait for eye shape is determined by a single gene, with triangular eyes being dominant (represented by "T") and round eyes being recessive (represented by "t"), the first parent is heterozygous for eye shape (one dominant allele and one recessive allele) and the second parent is homozygous recessive for eye shape (two recessive alleles).
When these two organisms are crossed, the possible combinations of alleles in the offspring are as follows:
- 50% of the offspring will inherit the "T" allele from the first parent and the "t" allele from the second parent, resulting in the genotype "Tt". This corresponds to triangular eyes.
- The other 50% of the offspring will inherit the "t" allele from both parents, resulting in the genotype "tt". This corresponds to round eyes.
Therefore, the probability that an offspring would have round eyes is 50%, or 1:2.