Explanation:
When two parents with different traits are crossed, their offspring in the first filial (F1) generation inherit a combination of traits from both parents. However, not all traits are expressed in the same way. Some traits are expressed more prominently or mask the expression of other traits.

The traits that are expressed in the F1 generation are known as dominant traits. These traits are represented by capital letters in genetic notation. Dominant traits tend to be more visible or stronger in their expression.

Examples:
- In Mendel's pea plant experiments, when he crossed a yellow-seeded plant (YY) with a green-seeded plant (yy), all the offspring in the F1 generation had yellow seeds. The yellow seed color is a dominant trait, and it masked the expression of the recessive green seed color trait.
- Similarly, when a tall pea plant (TT) is crossed with a short pea plant (tt), all the offspring in the F1 generation are tall. The tall height is a dominant trait, and it masks the expression of the recessive short height trait.

Key Points:
- Dominant traits are expressed in the F1 generation.
- Dominant traits tend to be more visible or stronger in their expression.
- Dominant traits mask the expression of recessive traits.
- Dominant traits are represented by capital letters in genetic notation.
- Examples of dominant traits include yellow seed color, tall height, or curly hair.

Overall, the traits expressed in the F1 generation are known as dominant traits. These traits are more prominent or stronger in their expression and mask the expression of recessive traits.

It's answer is dominant example yellow seed coat The traits that is visible expressed.