GED Science TestLife ScienceMedium
A gardener observes that a particular type of plant consistently produces red flowers when self-pollinated, but when crossed with a different plant that produces white flowers, all offspring have pink flowers. This pattern of inheritance is best described as:
- ASex-linked inheritance
- BCodominance
- CComplete dominance
- DIncomplete dominance
Show answer & explanationAnswer & explanation
Correct answer: D. Incomplete dominance
In incomplete dominance, neither allele is completely dominant over the other, resulting in a heterozygous phenotype that is an intermediate blend of the two homozygous phenotypes, such as pink flowers from red and white parents.
Why the other options are wrong
- A. Sex-linked inheritance relates to genes on sex chromosomes and typically shows different patterns in males and females, which is not indicated here.
- B. Codominance would result in both red and white patches or distinct features appearing simultaneously, not a blend.
- C. Complete dominance would result in either red or white flowers, not pink, if one allele masked the other.
Incomplete Dominance
A genetic inheritance pattern where the heterozygous phenotype is intermediate between the two homozygous phenotypes, appearing as a blend rather than one allele completely masking the other.
- Neither allele is fully dominant
- Heterozygotes show a blended phenotype
- Example: red + white = pink flowers
- Genotypic and phenotypic ratios are often identical
Memory trick: Dominance can be Complete, Incomplete, Co-dependent, or Sex-linked.