In a plant, red fruit (R) is dominant over yellow fruit (r) and tallness (T) is dominant over shortness (t). If a plant with RRTt genotype is crossed with a plant that is rrtt:
Correct answer: B. 50% will be tall with red fruit
- A. 25% will be tall with red fruit
- B. 50% will be tall with red fruit
- C. 75% will be tall with red fruit
- D. All the offspring will be tall with red fruit
Explanation
When a plant with the genotype RRTt (red fruit and tall) is crossed with a plant that is rrtt (yellow fruit and short), the Punnett square analysis shows that 50% of the offspring will be tall with red fruit (genotype RTTt). Therefore, the correct answer is option b. The other options either overestimate or underestimate the percentage of offspring with the specified 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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