Question

Most fungi that cause harm to humans are not obligate human pathogens. In other words, these fungi are not highly adapted to attacking humans. How and why do these fungi cause harm?

Define what the great oxygen catastrophe was and what organisms caused it and were affected by it.

Answer 1

Fungi cause harm more in immunocompromised individuals than in normal individuals. A fungi named Aspergillus is present in outside air commonly. We intake them all the time. But if our defences in the airway system is somewhat damaged , as in immunocompromised individuals, we are at a risk of infection from Aspergillus. Some individuals may develop hypersensitivity to Aspergillus and this contribute to the cause of Asthma. The fungi can cause diseases through replication of the fungus. That is fungal cells can invade tissues and disrupt their function. They can also elicite immune response by antibodies. They cause disease also by consuming energy and nutrients intended for the host. They also cause disease by producing toxic substances by their metabolism. Generally speaking, diseases caused by fungi are just accidental. The circumstances were such that the fungi just tried to survive and the host or humans got diseases.

The great oxygen catastrophe was a time period when the atmosphere and ocean of earth experienced an elevation in amount of oxygen. The cyanobacteria are the organisms responsible for this. They produced oxygen and this changed the earth. Befor this catastrophe, the Earth's atmosphere was weakly reducing type. After this event, it changed to oxidizing atmosphere. Many other species of bacteria were harmed by this leading to their mass extinction.