Question

part a
you cross a true-breeding red-flowered snapdragon with a true-breeding white-flowered one. all of the f₁ are pink. what does this say about the parental traits?
view available hint(s)
both red and white are pleiotropic.
pink is dominant, and red and white are recessive.
red shows incomplete dominance over white.
red is completely dominant.

Explanation:

In snapdragon flower color, crossing true - breeding red and white gives pink F₁. This is incomplete dominance, where neither allele (red or white) is completely dominant, and the heterozygote shows an intermediate phenotype (pink). Let's analyze each option:

• Option 1: Pleiotropy is when one gene affects multiple traits, not related here. Eliminate.
• Option 2: If pink were dominant, F₁ should be pink only if pink is the dominant allele, but parents are red and white, so this is wrong. Eliminate.
• Option 3: Incomplete dominance matches the intermediate (pink) phenotype from red and white parents. Correct.
• Option 4: Complete dominance would result in F₁ having the dominant color (red or white), not pink. Eliminate.

Answer:

Red shows incomplete dominance over white.