In humans, the trait for tongue rolling is dominant over the trait for the inability of a human to roll his/her tongue. if a heterozygous male is crossed with a homozygous recessive female, then what percent of the offspring would be expected to have the ability to roll their tongues

Heterozygous means that the father has one dominant gene for tongue-rolling, and one recessive gene for non-tongue-rolling. The mother is homozygous recessive, meaning she has two copies of the non-tongue-rolling gene. This means that every child is guaranteed a non-rolling gene from their mother, and they have a 50% chance of inheriting a rolling gene from their father. Since the rolling gene is dominant, only one copy of the gene is required to show the trait, so the 50% of children with the rolling gene from their father will be able to roll their tongues. The answer is 50% of offspring.