SECTION A Question 1 Alultiple Cingiae 1.1 The control centre of a living cell is the - A chromosome. B cell membrane. C cytoplasm. D nucleus. 1.2 Viruses... A occur only in water. B are living organlsms. C are pathogenic. D can cause foods to decay. 1.3 Viruses are said to be living because. A they can respire. B they can regroduce on their own.

The discovery of the nucleus as the control center of a living cell was a pivotal moment in cellular biology. It was first identified in 1831 by Robert Brown, who recognized the nucleus as a distinct structure within plant cells. Since then, scientists have found that the nucleus houses DNA, which contains the genetic instructions essential for cellular function and replication, making it vital to life itself. Viruses often spark debates about their classification as living organisms. They lack the cellular machinery required for metabolism and reproduction, causing some to argue they aren't truly "alive." However, they can only replicate by hijacking a host cell's machinery, which is why they are considered complex entities straddling the line between living and non-living. Their interactions with hosts lead to both interesting and harmful consequences in ecosystems and human health alike!