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GCE Biology 1989 Question 38

Question 38

Mendelian Inheritance

Which of the following represents the phenotypic ratio, when a plant Rr is crossed with another plant Rr, assuming that the gene R for round seed is dominant and wrinkled r is recessive?

  1. A.1:2:1
  2. B.2:2:1
  3. C.3:2
  4. D.3:1
  5. E.4:1
Show the answer and explanation

Answer: D (3:1)

Explanation

Rr × Rr gives RR, Rr, Rr, rr: three round to one wrinkled.