16% of people in a population can not roll their tongue .what is the frequency of people which are heterozygous of this character? Please ,any one help and guide me to solve these kind of problems. I tried to solve it using punnet square but i failed . enter image description here

So i tried my best please help me to solve this.

  • $\begingroup$ Homework questions are off-topic on Biology unless you have shown your attempt at an answer. For more information see our homework policy. $\endgroup$
    – David
    Commented May 26, 2018 at 8:50
  • 1
    $\begingroup$ @David He show some attempt. $\endgroup$
    – L.Diago
    Commented May 26, 2018 at 9:19
  • $\begingroup$ Possible duplicate of Solving Hardy Weinberg problems $\endgroup$
    – Remi.b
    Commented May 26, 2018 at 16:09
  • $\begingroup$ Hint: The very first step is to define which genotype can not roll their tongue. Then, you know that 16% of the population have these genotypes. From this, you can find out the frequency of heterozygote in the population thanks to Hardy-Weinberg. For more information, please look at the post marked as duplicate. $\endgroup$
    – Remi.b
    Commented May 26, 2018 at 16:12

1 Answer 1


I definitely recommend looking at your calculations. The "unable to roll tongue" trait is recessive, not dominant. Look at the Hardy-Weinberg equation $p^2 + 2pq + q^2 = 1$. Try to extract the root of $q^2$ and you will get the right solution.


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