The F1 generation of a Mendelian monohybrid cross between two true-breeding parents will have the following characteristic:
"All individuals in the F1 generation will display the same phenotype as one of the parents, showing dominant traits for the specific trait being studied."
In Mendelian genetics, a monohybrid cross involves the mating of two individuals that are homozygous (true-breeding) for different alleles of a single gene. One parent will carry two copies of the dominant allele (AA), and the other parent will carry two copies of the recessive allele (aa). When these parents are crossed, all their offspring in the F1 generation will inherit one copy of the dominant allele from one parent and one copy of the recessive allele from the other parent (Aa).
Since the dominant allele masks the effect of the recessive allele in heterozygous individuals (Aa), the F1 generation will all display the same phenotype as one of the parents (having the dominant trait) due to the dominance of the dominant allele over the recessive allele.