NEETZoologyPrinciples of Inheritance and Variation
Read the following statements regarding the inheritance of traits: Statement I: In Antirrhinum, the F₁ heterozygote does not resemble either of the two parents. Statement II: In human skin colour, the phenotype reflects the additive contribution of each dominant allele. Statement III: Phenylketonuria is a disease where a single mutant gene causes multiple phenotypic expressions. Statement IV: In ABO blood grouping, t
Options
- AOnly three
- BAll four
- COnly two
- DOnly one
Correct answer
A. Only three
Step-by-step solution
Statement I is correct: In Antirrhinum (snapdragon), flower colour shows incomplete dominance, where the F₁ phenotype is intermediate and does not resemble either parent. Statement II is correct: Human skin colour is an example of polygenic inheritance where the effect of each dominant allele is additive. Statement III is correct: Phenylketonuria is a classic example of pleiotropy, where a mutation in a single gene leads to multiple phenotypic effects such as mental retardation and a reduction in hair and skin pigm