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Incomplete Dominance MCQ - Practice Questions with Answers

Edited By admin | Updated on Sep 18, 2023 18:34 AM | #NEET

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  • 14 Questions around this concept.

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In incomplete dominance F1 ratio of _________ is 1:2:1 
 

In Antirrhinum two plants with pink flowers were hybridized. The F1 plants produced red, pink and white flowers in the proportion of 1 red, 2 pink and 1 white. What could be the genotype of the two plants used for hybridization? Red flower colour is determined by RR, and white by rr genes.

Example of incomplete dominance - "Snapdragon" is also known as 

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How many hybrid flower (Rr) is form in incomplete dominance

F2 generation in a Mendelian cross showed that both genotypic and phenotypic ratios are the same as 1: 2: 1. It represents a case of:

In Antirrhinum (dog flower ), the phenotypic ratio in F2 generation for the inheritance of flower colour would be

In Antirrhinum (Snapdragon), a red flower was crossed with a white flower and in the F1 generation, pink flowers were obtained. When pink flowers were selfed, the F2 generation showed white, red and pink flowers. Choose the incorrect statement from the following:

 

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Concepts Covered - 1

Incomplete Dominance
  • Mendel’s results, that traits are inherited as dominant and recessive pairs, contradicted the view at that time that offspring exhibited a blend of their parents’ traits.
  • When experiments on peas were repeated using other traits in other plants, it was found that sometimes the F1 had a phenotype that did not resemble either of the two parents and was in between the two.
  • For example, in the snapdragon, Antirrhinum majus a cross between a homozygous parent with white flowers (rr) and a homozygous parent with red flowers (RR) will produce offspring with pink flowers (Rr).
  • This pattern of inheritance is described as incomplete dominance, denoting the expression of two contrasting alleles such that the individual displays an intermediate phenotype.
  • Here the genotype ratios were exactly as we would expect in any mendelian monohybrid cross, but the phenotype ratios had changed from the 3:1 dominant : recessive ratio.
  • What happened was that R was not completely dominant over r and this made it possible to distinguish Rr as pink from RR (red) and rr (white).
  • The allele for red flowers is incompletely dominant over the allele for white flowers.
  • However, the results of a heterozygous self-cross can still be predicted, just as with Mendelian dominant and recessive crosses. 
  • In this case, the genotypic ratio would be 1:2:1.

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Incomplete Dominance

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Incomplete Dominance

Biology Textbook for Class XII

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