Study the graph given below. Explain how oxygen concentration is affected in the river when sewage is discharged into it.
The introduction of sewage caused a sudden and sharp drop in the amount of dissolved oxygen in the river. This is caused due to an increase in the biological oxygen demand (BOD). This in turn leads to the death of fishes and other aquatic life. As the sewage gets diluted due the flow of the water, the river slowly regains some of its oxygen concentration.
Write the scientific names of the causal organisms of elephantiasis and ringworm in humans. Mention the body parts affected by them.
