in a population of plants, the allele for long stems (S) is completely dominant over the allele for short stems (s). If 35% of the population has short stems, calculate the percentage of the population that is expected to be heterozygous (Ss).

We solve the problem using the Hardy-Wineberg equation.

Let us start with the homozygous recessive percentage first,

q² = 35/100 = 0.35

We have the frequency for short stem (s) as q = √0.35 = 0.59

Solving for the frequency of long stem (S) by using the fact that,

p + q = 1

∴ p = 1 - q = 1 - 0.59 = 0.41

So the long stem (S) has a frequency of 0.41.

Now we can calculate 2pq which is the heterozygous alleles (Ss) frequency.

∴ 2pq = 2 x 0.59 x 0.41 = 0.48

Hence 48% of the population is heterozygous for long stem.