Biology Inheritance / Variation & Genetics PMC 2020
PMDC Verified Question 69 of 94
Incomplete dominance:
A
Different alleles of a gene are both expressed in heterozygous condition
B
One allele is completely dominant over the other and the presence of the recessive allele is functionally hidden so the heterozygote has the same round phenotype as homozygote.
C
The phenotype of the heterozygote is intermediate between phenotypes of the two homozygotes.
D
Gene mutations may produce many different alleles of a gene.
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Official Correct Choice:
Option C: The phenotype of the heterozygote is intermediate between phenotypes of the two homozygotes.
Concept:

Incomplete dominance is a form of intermediate inheritance where neither allele is completely dominant over the other.

Solution:

  • In incomplete dominance, one allele does not completely mask the effects of the other.
  • This results in a physical appearance that shows a blending of both alleles.
  • Therefore, the phenotype of the heterozygote is strictly intermediate between the phenotypes of the two homozygous parents (e.g., Red x White = Pink flowers).


Why other options are incorrect:

  • Option A: Describes co-dominance, where both alleles are fully and distinctly expressed (e.g., AB blood group).
  • Option B: Describes complete Mendelian dominance.
  • Option D: Describes the concept of multiple alleles.

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