Question

which statement describes the $f_1$ generation of a mendelian monohybrid cross between two true - breeding parents?

• only the dominant trait is visible in the $f_1$ generation.
• only the recessive trait is visible in the $f_1$ generation.
• neither the dominant nor recessive trait is visible in the $f_1$ generation.
• both the dominant and recessive traits are visible in the $f_1$ generation.

Explanation:

In a Mendelian monohybrid cross, true-breeding parents are homozygous: one is homozygous dominant (e.g., $AA$) and the other is homozygous recessive (e.g., $aa$). When crossed, all offspring in the $F_1$ generation inherit one dominant allele and one recessive allele ($Aa$). Dominant alleles mask the expression of recessive alleles, so only the dominant trait is phenotypically visible.

Answer:

Only the dominant trait is visible in the $F_1$ generation.