In peas, the gene for yellow color (C) is dominant to the gene for green color (c). To determine the genotype of an unknown yellow pea, what kind of pea should you cross with it?
Correct answer: D. Homozygous recessive (cc)
- A. Another unknown green pea
- B. Any genotype
- C. Homozygous dominant
- D. Homozygous recessive (cc)
Explanation
A green pea would definitely be homozygous recessive. A is the best option because if the unknown dominant individual is heterozygous, then the offspring of this year's cross will include some recessive individuals. If the unknown is homozygous, then all offspring will be dominant heterozygous. In this way, crossing an unknown dominant phenotype with a recessive individual is the surest way of determining the unknown genotype.
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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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