Hardy-weinberg and varience

[tRNA]

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Hi All,
1)I am looking for more hardy-weinberg problems to practice with, since i am very bad with those, i couldn't find any good ones on google and even my campbell Bio book only has 3 or 4 problems, plz let me know if you find a source of weinberg problems, like 15-20 problems

2) Do we have to know how to calculate standard deviation and variance on the dat, the ADA sample test has a variance problem but all kaplan tests don't?
thanks and good luck

 

[CyborgNinjaX]

For the first question, I say you should probably try Schuam's Biology. According to Amazon.com's description of it, there are over 800 problems (Biology as a whole, not just H-W) in there. Somebody who has actually bought it can tell me if I am right or wrong.

 

[Streetwolf]

Hardy Weinberg:

Know that p^2 + 2pq + q^2 = 1. This is a direct result of the fact that p + q = 1 so (p + q)^2 = 1^2 = 1. And of couse (p + q)^2 = p^2 + 2pq + q^2.

The types of questions you may get:

Q: The dominant allele frequency is 'x'. What is the heterozygous frequency?
A: p = x so q = 1 - x. Thus heterozygous = 2pq = 2(x)(1-x)

Q: Two creatures mate and their offspring recessive homozygous frequency is 'x'. What is the dominant frequency?
A: q^2 = x so q = sqrt(x) so p = 1 - sqrt(x)

Q: Two creatures mate and their offspring heterozygous frequency is 'x'. The dominant allele frequency is 'y'. What is the recessive homozygous frequency in the offspring?
A: 2pq = x and p = y so 2yq = x so q = x/2y so q^2 = (x/2y)^2 = x^2 / 4y^2.

Stuff like that. Just manipulating the formula. They'll actually give you decimals though, not 'x' or 'y'.


For standard deviation, I'd be surprised if you came across one but here is the formula:

First consider the mean = x(bar). Now consider each individual data point = x(i).

Take (x(bar) - x(i))^2 for each i (each data point). Add all of those up. Divide by (i-1). That's the variance.

The standard deviation is the square root of the variance.

So for example if you have 4, 5, 7, 10, 14 are your numbers, then x(bar) is the mean = 8. Now take (8-4)^2 = 16, (8-5)^2 = 9, (8-7)^2 = 1, (8-10)^2 = 4, and (8-14)^2 = 36.

16 + 9 + 1 + 4 + 36 = 66.
Now take 66 / 4 = 16.5

Your variance is 16.5.

The standard deviation is sqrt(16.5) ~ 4.06.