In 'Complete Dominance':
Correct answer: B. One allele (R) is completely dominant over the other (r) and the presence of the recessive allele is functionally hidden, so the heterozygote (Rr) has the same round phenotype as the (RR) homozygote.
- A. Different alleles of a gene are both expressed in heterozygous condition
- B. One allele (R) is completely dominant over the other (r) and the presence of the recessive allele is functionally hidden, so the heterozygote (Rr) has the same round phenotype as the (RR) 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
Explanation
Complete dominance is a form of dominance in a heterozygous condition wherein the allele that is regarded as dominant completely masks the effect of the allele that is recessive. Option C refers to 'Incomplete Dominance' where a dominant allele, or form of a gene, does not completely mask the effects of a recessive allele, and the organism's resulting physical appearance shows a blending of both alleles.
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About Inheritance
Mendel's laws explain segregation, independent assortment and the prediction of genetic ratios using alleles, genotypes and phenotypes. The chapter also covers linked genes, recombination and crossing over during meiosis, then applies pedigree reasoning to X-linked recessive traits, which show different inheritance patterns in males and females.
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