Question

a purebred plant that has yellow flowers is crossed with a purebred plant that has white flowers. all the offspring have yellow flowers. which conclusion about yellow flowers is supported by these results?
○ yellow flower color is a dominant trait.
○ yellow flower color is a recessive trait.
○ yellow flower color is a heterozygous trait.
○ yellow flower color is a monohybrid trait.

Explanation:

In genetics, when two purebred (homozygous) organisms with different traits are crossed, the trait that appears in all offspring is the dominant trait. Here, purebred yellow - flowered and purebred white - flowered plants are crossed, and all offspring have yellow flowers. A recessive trait (like white here, since it's masked) would not be expressed in the offspring when crossed with a dominant - trait - carrying purebred. A heterozygous trait refers to having two different alleles, but the offspring here are showing the expression of the yellow trait from the cross of two purebreds, so yellow isn't heterozygous in this context. A monohybrid trait refers to a cross involving one trait, but the key here is the dominance of the yellow trait. So yellow flower color is a dominant trait.

Answer:

A. Yellow flower color is a dominant trait.