Which statement best describes an understanding of genetics that would be missing without the work of Mendel?

Mendel’s pea-plant experiments showed that traits can be controlled by inherited factors, and that one form can mask another. These forms are now called alleles, and the masking form is dominant while the masked form is recessive. The molecular role of DNA and proteins was discovered through later work, so choices B and D are not specifically what Mendel’s work established.

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