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MDCAT Biology QUESTION #4306
Question 1
In a pea plant, seed color is determined by two alleles: Y (Yellow, dominant) and y (green, recessive). Which parental cross would result in a 1:1 ratio of yellow to green seeds?
  • $Yy \times YY$
  • $Yy \times yy$✔️
  • $Yy \times Yy$
  • $YY \times yy$
Correct Answer Explanation
A test cross $Yy \times yy$ gives 50% $Yy$ (yellow) and 50% $yy$ (green), resulting in a $1:1$ ratio. This is the classic test cross used to determine genotype.