A garden has 400 sweet pea plants. Of these, 180 are AA, 120 are Aa and 100 are aa…
Contributed by StemPy LabTry it on paper first. A hint, the key idea and the worked solution are here when you need them.
A garden has 400 sweet pea plants. Of these, 180 are , 120 are and 100 are .
- What is the frequency of the allele ?
- What is the frequency of the allele ?
- Suppose that these plants mate at random. How many plants are expected among 400 plants of the next generation?
Need a reminder? The key ideaShow
Count gene copies: each individual has two. The frequencies of two alleles add up to 1. At equilibrium the genotypes are . Start from the recessive trait, which shows . The five factors that disturb the equilibrium are gene flow, drift, mutation, recombination and selection.
The worked solution
Have you tried it?
Work it out on paper first. It is fine to get stuck or make a mistake: that is how we learn. When you are ready, go through the solution one step at a time, and check each step against your own.
Given. , , . The total is plants, which hold gene copies.
Plan. Count the copies of each allele. Then use .
Step 1. (a) Copies of : . .
Step 2. (b) . Check: copies of are , and .
Step 3. (c) . Among plants: plants.
Answer: ; ; plants.
Check. The plants of the sample had only heterozygotes, fewer than . So the sample was not in equilibrium. After random mating, the heterozygotes rise.
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