In a pea plant seed color is determined by two alleles: Y (Yellow, dominant) and y (green, recessive). Which parental cross would most likely result in offspring showing a 1:1 ratio of yellow to green seeds?
Correct answer: B. Yy x yy
- A. Yy x YY
- B. Yy x yy
- C. Yy x Yy
- D. YY x yy
Explanation
Crossing a heterozygote with a homozygous recessive gives half Yy and half yy, that is one yellow to one green, which is the classic test cross. Yy by Yy gives three yellow to one green, and any cross involving YY gives all yellow because every offspring receives at least one dominant allele. Recognising the test cross by its 1:1 outcome is the quickest route.
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About Mendel's Laws of Inheritance
Mendelian inheritance explains how alleles separate into gametes and assort during reproduction, producing predictable genotype and phenotype ratios. Questions cover dominance, recessiveness, homozygous and heterozygous conditions, the laws of segregation and independent assortment, monohybrid and dihybrid crosses, test crosses and the limits caused by linked genes.
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