Asked in Premeth past paper pool — BiologyModerate

In pea plants, the allele of inflated pod shape (I) is dominant over constricted pod shape (i) and the allele of yellow pod colour (Y) is dominant over green pod colour (y).If 112 offspring are produced by this cross, then out of these the number of offspring with constricted green pods would be

Correct answer: A. 7

  • A. 7
  • B. 14
  • C. 28
  • D. 56

Explanation

In a dihybrid cross of pea plants where inflated pod shape (I) is dominant to constricted (i) and yellow pod color (Y) is dominant to green (y), if 112 offspring are produced, approximately 7 offspring will have constricted green pods. This is because the expected phenotypic ratio of a dihybrid cross is 9:3:3:1, with the double recessive phenotype (constricted green) appearing in a proportion of 1/16 of the offspring. Therefore, (1/16) * 112 = 7. So option A is correct and B,C and D are wrong.

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About Mendel's Laws of Inheritance

Mendelian inheritance explains how alleles separate into gametes and assort during reproduction, producing predictable genotype and phenotype ratios. Questions cover dominance, recessiveness, homozygous and heterozygous conditions, the laws of segregation and independent assortment, monohybrid and dihybrid crosses, test crosses and the limits caused by linked genes.

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