Percentage of Genotype Expression
The percentage of individuals with a given genotype that expresses the expected phenotype is known as-
- Epistasis
- Expressivity
- Penetrance — Correct Answer
- Recessive
Explanation:
Correct Answer: Penetrance
Penetrance is defined as the percentage (proportion) of individuals with a given genotype that actually expresses the expected phenotype. It is an "all-or-nothing" concept.
Penetrance — Key Facts
- Formula: Penetrance (%) = (No. of individuals showing expected phenotype / Total individuals with that genotype) × 100
- Complete penetrance: 100% of individuals with the genotype show the phenotype
- Incomplete penetrance: Less than 100% expression (e.g., some individuals with the dominant allele do not show the trait)
- Example: Polydactyly in humans shows incomplete penetrance
Penetrance vs. Expressivity — Comparison
| Feature | Penetrance | Expressivity |
|---|---|---|
| Definition | % of genotype carriers that express phenotype | Degree/extent of phenotypic expression |
| Nature | All-or-nothing (qualitative) | Graded (quantitative) |
| Question answered | Does the trait appear? | How strongly does the trait appear? |
Why Other Options Are Wrong
- Epistasis → gene interaction where one gene masks another; not about % expression
- Expressivity → degree/extent of expression, not the percentage of individuals expressing it
- Recessive → a type of allele, not a term for % expression
📚 About this Topic — Animal Genetics & Breeding
This multiple choice question is from Animal Genetics & Breeding, Animal Refresher. It has 4 options with a detailed explanation of the correct answer. Practice more MCQs from Animal Genetics & Breeding to strengthen your preparation.
