In a cross between a male and female, both heterozygous for sickle cell anaemia gene, what percentage of the progeny will be diseased?

The correct answer is option 4. Concept: • In heterozygous genotype, two alleles of different types interact with each other. • The allele which is strongly expressed is called the dominant allele and the one which is masked is called the recessive allele. • If parents are heterozygous for a disease condition, they won't get the disease but there is a finite probability that some percent of their possible progenies might develop the disease. Explanation: Let us see the result of a cross between two heterozygous parents for sickle cell anemia. • Forparents, let Hb Abe the dominant allele while Hb Sbe the recessive allele responsible for sickle cell anemia. • Now let us see the cross between the parents: • In the results,there are 4 possibleF 1progenies; • Hb AHb A(unaffected; will neither have nor will carry sickle cell anemia) • Hb A Hb S(unaffected; will not havesickle cell anemia but are carriers of the disease) • Hb SHb S( affected with sickle cell anemia) • The number of F 1progeny affected with sickle cell anemia is 1 out of 4 possible progenies i.e 1/4 = 0.25 • The percentageof F 1 progeny affected with sickle cell anemia is 0.25 X 100 = 25 % So, the correct answer is option 4.

In a cross between a male and female, both heterozygous for sickle cell anaemia gene, what percentage of the progeny will be diseased? 1. 25% 2. 100% 3. 50% 4. 75% Recommended PYQs (STRICTLY NCERT Based) Principles of Inheritance & Variation Botany - Past Year Questions NEET Practice Questions, MCQs, Past Year Questions (PYQs), NCERT Questions, Question Bank, Class 11 and Class 12 Questions, and PDF solved with answers