Fungi? Question is a bit vague.
I think it would be A. Helicase
Answer:
The fraction of heterozygous individuals in the population is 32/100 that equals 0.32 which is the genotipic proportion for these endividuals.
Explanation:
According to Hardy-Weinberg, the allelic frequencies in a locus are represented as p and q, referring to the alleles. The genotypic frequencies after one generation are p² (Homozygous for allele p), 2pq (Heterozygous), q² (Homozygous for the allele q). Populations in H-W equilibrium will get the same allelic frequencies generation after generation. The sum of these allelic frequencies equals 1, this is p + q = 1.
In the exposed example, the r-6 allelic frequency is 0,2. This means that if r-6=0.2, then the other allele frequency (R) is=0.8, and the sum of both the allelic frequencies equals one. This is:
p + q = 1
r-6 + R = 1
0.2 + 0.8 = 1
Then, the genotypic proportion for the homozygous individuals RR is 0.8 ² = 0.64
The genotypic proportion for the homozygous individuals r-6r-6 is 0.2² = 0.04
And the genotypic proportion for heterozygous individuals Rr-6 is 2xRxr-6 = 2 x 0.8 x 0.2 = 0.32
The mechanism is straightforward: in Metaphase one of Meiosis, chromosomes line up in two lines, with homologous across from each other, which allows them to interact by crossing over. In Metaphase of Mitosis, the chromosomes are all lined up single file, so the homologous chromosomes cannot interact.
Skeletal system.
Without a proper skeleton, we would not have enough rigidity to properly move. We'd be an awkward pile of skin, muscle & bodily fluids.
Hope that helps!