A colour blind girl is rare because she will be born only when:
Correct answer: B. Her father and maternal grand father were colour blind
- A. Her mother and maternal grand father were colour blind
- B. Her father and maternal grand father were colour blind
- C. Her mother is colour blind and father has normal vision
- D. Parents have normal vision but grand parents were colour blind
Explanation
The correct option is b) Her father and maternal grandfather were color blind. Color blindness is a sex-linked recessive disorder that is carried on the X chromosome. The inheritance pattern of color blindness follows an X-linked recessive pattern. In this pattern, a female can be affected by color blindness if she inherits two copies of the recessive allele, one from her father and one from her mother.
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About Inheritance
Mendel's laws explain segregation, independent assortment and the prediction of genetic ratios using alleles, genotypes and phenotypes. The chapter also covers linked genes, recombination and crossing over during meiosis, then applies pedigree reasoning to X-linked recessive traits, which show different inheritance patterns in males and females.
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