Question

short pea plants exist in the p₁ and f₂ generations. what happens to the phenotype in the f₁ generation?
the allele for short pea plants is absent from the genotypes in the f₁ generation.
the allele for short pea plants is masked during the f₁ generation, but it is still present in the genotype.
the allele for short pea plants is not passed on to the f₁ generation.
done
p₁
short pea plant tall pea plant
f₁
all tall pea plants
f₂
3 tall : 1 short

Explanation:

This question is about genetics in pea plants, related to allele expression. In Mendelian genetics, a dominant allele (for tallness here) masks a recessive allele (for shortness) in the heterozygous F₁ generation. The short allele is still present in the genotype (heterozygous) but not expressed phenotypically. The first option is wrong as the short allele is present. The third is wrong as the allele is passed on (seen in F₂ short plants). So the second option is correct.

Answer:

The allele for short pea plants is masked during the F₁ generation, but it is still present in the genotype.