Prokaryotic cells and virusesAQA A-Level Biology: Mind map

Exam questions on Prokaryotic cells and viruses

1. A student compares the bacterium Escherichia coli, which is about 2 μm long, with a human liver cell, which is about 25 μm across.
   State two differences between the DNA of E. coli and the DNA of the human liver cell.2 marks
2. Some antibiotics work by binding to bacterial ribosomes and stopping protein synthesis, but they do not affect protein synthesis in the cells of the person taking them. A scientist is investigating why.
   Suggest why an antibiotic that binds to bacterial ribosomes is unlikely to harm human cells, and why it stops the bacteria from growing.2 marks
3. Pseudomonas aeruginosa is a bacterium that infects the lungs of patients with cystic fibrosis. Each cell has a capsule, flagella and several plasmids, and one plasmid carries a gene for antibiotic resistance. The bacteria live alongside human lung epithelial cells.
   Suggest how the capsule, the flagella and the plasmids help Pseudomonas aeruginosa to survive and spread in the lungs.3 marks