Read the passage below to answer the question: Hemophilia is a disorder in which blood fails to clot. Saad, a male hemophiliac, marries Sara, a normal woman and together they have four children, two boys (Ahmed and Ali) and two girls (Alia and Ayesha). None of the children display the symptoms of Hemophilia. Ahmed, Ali, Ayesha, and Ali all marry normal individuals and have children. None of Ahmed or Ali's children, male or female, display symptoms of hemophilia, but the sons of Alia and Ayesha display symptoms of hemophilia while the daughters of Alia and Ayesha do not. Which of the following individuals are heterozygous for hemophilia:
Correct answer: D. Alia and Ayesha
- A. Saad, Ahmed, and Ali
- B. Ahmed, Ali, Alia, and Ayesha
- C. Saad and Sara
- D. Alia and Ayesha
- E. Ahmed and Ali
Explanation
Male can't be heterozygous or homozygous because they can only have one allele. Females can possibly be homozygous or heterozygous. Heterozygous are those females that are carriers as we know that Alia and Ayesha do not show any symptoms.
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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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