Binary fission and virus replicationAQA A-Level Biology: Mind map

Exam questions on Binary fission and virus replication

1. A microbiologist inoculated a flask of sterile nutrient broth with a single Escherichia coli cell. Under these conditions each cell divides by binary fission once every 20 minutes and none of the cells die.
   Explain why the daughter cells each contain exactly one copy of the circular DNA but may contain different numbers of plasmids.2 marks
2. A virologist is studying a bacteriophage, a virus that infects bacteria. When a phage attaches to a bacterium it injects its nucleic acid into the host cell and its protein coat stays outside.
   Explain why phages cannot replicate in sterile nutrient broth that contains no bacteria.2 marks
3. A hospital laboratory is investigating two patients: one has a bacterial infection and the other has a viral infection.
   Describe how a virus replicates after it has attached to a host cell.3 marks