Stem height in the pea plant is one of the traits studied by Mendel. The tall allele is dominant to the short stem allele. What is the probability of a tall offspring if two heterozygous plants are mated? What proportion of the tall offspring is likely to be homozygous?
Use a Punnett Square.
http://anthro.palomar.edu/mendel/mendel_2.htm
A plant 3 centimeters tall is placed by a window. If it grows 4 centimeters a day, how many days will it take to be 51 centimeters tall?
To determine the probability of a tall offspring when two heterozygous plants are mated, we need to understand Mendel's laws of inheritance and apply them to this scenario.
Mendel's first law, the law of segregation, states that when individuals with two different alleles for a trait reproduce, each offspring inherits only one allele from each parent. This means that each parent plant will randomly pass on either the tall allele (T) or the short stem allele (t) to their offspring.
Given that the tall allele (T) is dominant to the short stem allele (t), we can represent the genotype of each heterozygous plant as Tt. When these two plants are mated, their possible combinations of alleles are:
- Tt (from the first parent) x Tt (from the second parent), which can result in the following offspring genotypes: TT, Tt, Tt, tt.
Among these four possible genotypes, three have at least one tall allele (TT, Tt, Tt), and only one genotype is homozygous for the short stem allele (tt). Therefore, the probability of obtaining a tall offspring is 3/4 or 75%.
To determine the proportion of the tall offspring that is likely to be homozygous, we need to consider the genotypes of the tall offspring only (TT, Tt, Tt). Out of these genotypes, only one is homozygous for the tall allele (TT), while two are heterozygous (Tt, Tt). Hence, the proportion of the tall offspring that is likely to be homozygous is 1/3 or approximately 33.3%.
In summary:
- The probability of a tall offspring when two heterozygous plants are mated is 75%.
- The proportion of the tall offspring that is likely to be homozygous is approximately 33.3%.