GCSE Biology Question Analyses Topic: Biology - Short Questions
1) Although a prokaryotic cell has no defined nucleus, yet DNA is not scattered throughout the cell. Explain.
2) Explain the effect on the characteristics of a river when urban sewage is discharged into it.
1) The nuclear material in a prokaryote is referred to as a nucleoid because prokaryotic cells lack a clearly identifiable nucleus. Prokaryotic nucleoids contain tightly wound circular double-stranded DNA that is of the circular type. Hence, even though prokaryotes lack a clearly defined nucleus, the DNA is not dispersed throughout the cell because of the circular structure and tight coiling.
2) Sewage from urban areas includes that from residences, medical facilities, and businesses. Pathogenic bacteria may be present in sewage from homes and hospitals, which could cause illness outbreaks. Sewage from industrial sources may contain toxic substances, heavy metals, and other pollutants that are extremely hazardous to aquatic life. As a result, the river's water may become dark from all the waste and become devoid of all aquatic life.
End of analysis. Great!