Microorganism protect themselves against harmful UV light and visible light by using Iron minerals around themselves.
The iron minerals have unique properties in that they block damaging UV radiation while yet allowing organisms to utilise the portion of sunlight required for photosynthesis. UV rays kill cells by damaging their DNA. Two molecules of thymine, one of the bases that makes up DNA, react when exposed to light. The thymine dimer that results is extremely stable. The cell cannot perform its usual tasks if cellular processes are interfered as a result of an inadequate repair or unrepaired damage of thymine dimer.
Microorganisms use the iron minerals in their surroundings to shield them from damaging UV and visible light.
In the presence of sunshine, some bacteria that require light may consume dissolved iron and perform photosynthesis. However, they did not emit oxygen throughout the process, unlike modern green plants. Rust and other iron minerals are waste products of the process. Because the iron minerals absorb the damaging UV radiation, organisms may still utilize the portion of sunlight required for photosynthesis. Compared to today's seas, the quantity of iron needed to create the minerals was far higher.
The reason that the answer is 1/4 is because the young man, his grandfather, his father, and his mother equal 4 people. The young man is 1 person. 1 person/4 people = 1/4.
