Incomplete dominance examples Biology

📚 Quick Study Guide

🧬 Incomplete Dominance: A type of inheritance where the heterozygous genotype results in a phenotype that is intermediate between the two homozygous phenotypes. 🌸 Key Characteristics:
🧪 Neither allele is completely dominant. 🌱 The heterozygous phenotype is a blend of the homozygous phenotypes. 🌺 Genotypic ratio in the offspring often matches the phenotypic ratio.
🖍️ Examples:
🦁 Flower color in snapdragons (red, white, and pink). 🐔 Feather color in chickens (black, white, and blue-gray). 🧶 Human hair texture (curly, straight, and wavy).
💡 Punnett Squares: Use Punnett squares to predict the genotypic and phenotypic ratios of offspring, remembering that heterozygotes will display the intermediate phenotype.

Practice Quiz

1. Which of the following is the BEST description of incomplete dominance?
   1. Both alleles are expressed equally.
   2. One allele is completely dominant over the other.
   3. The heterozygous phenotype is a blend of the two homozygous phenotypes.
   4. One allele masks the expression of the other.
2. In snapdragons, red flowers (RR) are crossed with white flowers (WW), resulting in pink flowers (RW). What is the phenotypic ratio of the offspring if two pink flowers are crossed?
   1. 3 red : 1 white
   2. 1 red : 2 pink : 1 white
   3. 1 red : 1 pink : 2 white
   4. 2 red : 1 pink : 1 white
3. If a black feathered chicken (BB) is crossed with a white feathered chicken (WW) and produces blue-gray feathered offspring (BW), what type of inheritance is this an example of?
   1. Complete dominance
   2. Codominance
   3. Incomplete dominance
   4. Sex-linked inheritance
4. In a certain plant, the allele for tall stems (T) shows incomplete dominance over the allele for short stems (t). If a tall plant (TT) is crossed with a short plant (tt), what percentage of the offspring will have medium stems (Tt)?
   1. 0%
   2. 25%
   3. 50%
   4. 100%
5. A pink snapdragon is crossed with a white snapdragon. What percentage of the offspring will also be pink?
   1. 0%
   2. 25%
   3. 50%
   4. 75%
6. Which of the following genotypes would result in the intermediate phenotype in incomplete dominance?
   1. Homozygous dominant
   2. Homozygous recessive
   3. Heterozygous
   4. All of the above
7. What is the genotypic ratio of the offspring when two blue-gray feathered chickens (BW) are crossed, given that black (B) and white (W) feathers exhibit incomplete dominance?
   1. 1 BB : 2 BW : 1 WW
   2. 3 BW : 1 WW
   3. 1 BB : 3 BW
   4. 2 BB : 1 BW : 1 WW