a. 0%.
18. An extra finger in humans is rare but is due to
a dominant gene. When one parent is normal
and the other parent has an extra finger but is
heterozygous for the trait, what is the
probability that the first child will be normal?
d. 75%.
b. 25%.
c. 50%.



Answer :

Final answer:

The probability of a child being normal when one parent is normal and the other is heterozygous for an extra finger trait is 25%.


Explanation:

The probability of the first child being normal:

  1. Parental Genetics: Parent 1 is normal, and Parent 2 is heterozygous for the extra finger trait.
  2. Determining Probabilities: Use Punnett squares to analyze genetic probabilities.
  3. Probability Calculation: The probability of the first child being normal is 25% (b).

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