Recessive traits often seem to disappear because two recessive alleles are needed to produce the recessive phenotype. They can skip a generation and then reappear if an individual inherits two copies of the recessive gene. Mendel's experiments revealed that phenotypes could be hidden in one generation, only to reemerge in subsequent generations.
Recessive traits disappear because recessivealleles can hide out in heterozygotes, allowing them to persist in gene pools and natural selection can only see the phenotype, not the genotype. While harmful recessive alleles will be selected against and it's almost impossible for recessivealleles to completely disappear from a gene pool.
It would be decreased significantly. The ETC makes 28 molecules of ATP so if it is disabled then you would only get your net gain of 2 ATP from glycolysis
