Answer:
Mitochondrial Disorder
Explanation:
The LHON stands for leber hereditary optic neuropathy is a type of mitochondrial disorder. The disorder is generally observed in young males. The mitochondrial disorder are transferred from mother to its progeny. The disorder causes retinal ganglion cells (RGCs) and the exons of RGCs to degenerate. The disorder causes sudden painless failure of vision. The disorder leads to loss of central vision, optic atropy and central scotoma.
The most of the individuals with LHON do not possess the signs of the disorder. The disorder is caused by mutation in maternal DNA, thus it is a type of mitochondrial disorder.
Gradual changes in the frequency of diseases over long periods are known as SECULAR TIME TRENDS. For example, the rate of mortality in USA due to coronary heart diseases over a period of time. Onset of puberty in girls is also a secular time trend.
Secular time trend is also referred as Secular Variation and Secular Drift.
C. Decreased death rate is the answer
Germ-line mutations are mutations that would be passed down to future generations, and recombinations are where the information each parent passes down to the offspring is shuffled.
The genetic variation would have to come from random events: False
Only alternate generations would express any genetic variable: False
Body cell mutations would be the only source of heritable genetic variation: False
There would be no new heritable genetic variation possible in the population: True
Temperature, viscosity, and amount of dissolved gases
