Answer:
If tall height is dominant to short height in pea plants and all the offspring show the dominant phenotype, then the genotype of the tall parent must be heterozygous (Tt).
To understand why, let's first review some basic principles of genetics. In this scenario, "tall height" is the dominant trait, represented by the letter "T," and "short height" is the recessive trait, represented by the letter "t."
When two pea plants are crossed, they each contribute one allele for the height trait to their offspring. If the tall parent has a genotype of Tt, it means it has one allele for tall height (T) and one allele for short height (t).
On the other hand, the short parent must be homozygous recessive (tt) since all the offspring show the dominant phenotype (tall height). This means that the short parent contributes the recessive allele (t) for short height to all of its offspring.
When the two parents are crossed (Tt x tt), each offspring inherits one allele from each parent. Since tall height is dominant, any offspring that inherit the dominant allele (T) from the tall parent will exhibit the tall phenotype.
In conclusion, if all the offspring show the dominant phenotype (tall height), the tall parent must have a heterozygous genotype (Tt) for the height trait.
Step-by-step explanation: