In a dihybrid cross between two plants heterozygous for seed shape and seed color (RrYy × RrYy), what phenotypic ratio is predicted by the law of independent assortment?
Answer and explanation
Correct answer: A. 9 round yellow : 3 round green : 3 wrinkled yellow : 1 wrinkled green
- Step 1: Dihybrid heterozygous cross (RrYy × RrYy) combines two independent monohybrid crosses (3:1) × (3:1). Step 2. Multiply probabilities: (3/4 R_ + 1/4 rr)(3/4 Y_ + 1/4 yy) = 9/16 R_Y_ (round yellow), 3/16 R_yy (round green), 3/16 rrY_ (wrinkled yellow), 1/16 rryy (wrinkled green). Answer: 9 round yellow : 3 round green : 3 wrinkled yellow : 1 wrinkled green. Why not the others: 1:1:1:1 is a dihybrid test cross; 9:7 is complementary gene interaction.
Practise more Genetics, Heredity, Evolution and Ecology.
Free questions with an explanation for every one, and full timed NECO Senior School Certificate Examination mock tests.
More Genetics, Heredity, Evolution and Ecology questions
- In a cross between two heterozygous tall pea plants (Tt × Tt), what is the expected phenotypic ratio among the offspring according to Mendel…
- When pure-breeding red four o'clock flowers (Mirabilis jalapa) are crossed with pure-breeding white flowers, all F1 offspring bear pink flow…
- A man with blood group AB marries a woman with blood group O. What are the possible blood groups of their biological children?
- In humans, sickle cell hemoglobin (HbS) is inherited as a codominant allele. If two carrier parents with sickle cell trait (HbA HbS × HbA Hb…
- Why is sex-linked red-green color blindness substantially more prevalent among human males than among females?
- Under what parental combination can Rhesus incompatibility disease (erythroblastosis fetalis / hemolytic disease of the newborn) occur in a…