The Ka/Ks ratio: a) indicates neutrality if it is higher than 1 b) indicates con
ID: 177504 • Letter: T
Question
The Ka/Ks ratio:
a) indicates neutrality if it is higher than 1
b) indicates constraint if it is significantly higher than 1
c) indicates positive selection if it is significantly greater than 1
d) all of the above
e) none of the above
The alpha or significance level commonly accepted in biological practice for basic research is?
a) p = 0.15
b) p = 0.25
c) p = 0.50
d) p = 0.01
e) None of the above.
A KA/KS rate of around 1.0 (not significantly different than one) is a sign of?
a) Positive selection according to McDonald and Kreitman.
b) Negative selection according to Fisher.
c) Neutrality according to Kimura.
d) None of the above.
Explanation / Answer
The Ka is the number of non-synonymous substitutions per non-synonymous site per time period and Ks is the number of synonymous substitutions per synonymous site per time period. Ka/Ks indicates the occurrence of positive selection if beta >0 or Ka/Ks is greater than 1. the answer (c) is correct.
The significance level or confidence interval is calculated as the 95% or 99%. Therefore, if p = 0.01, then it signifies that the confidence interval of testing the hypothesis is 99%. The answer (d) is correct.
Ka/Ks ratio less than 1 signifies purifying or stabilizing selection, greater than 1 tells positive or Darwinian selection and equal to 1 implies neutral ot null selection. Therefore, answer (c) is correct as the neutral theory of molecular evolution is proposed by Motoo Kimura.
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