Bacteria and virusesEdexcel A-Level Biology A: Flashcards
What these 15 flashcards ask
- Give four features of a bacterial cell.
- What is the cell wall of a bacterium made of?
- How do bacteria reproduce?
- Why are viruses described as acellular?
- What are the main parts of a virus?
- Give two differences in size between bacteria and viruses.
- Why can viruses only replicate inside host cells?
- Why do antibiotics not work on viruses?
- How is TB transmitted?
- Why does M. tuberculosis survive in macrophages?
- Name four symptoms of TB.
- What is a retrovirus?
- Which cells does HIV infect, and which receptor does it bind?
- Why do HIV patients die from other infections?
- How does HIV differ from AIDS?
Exam questions on Bacteria and viruses
- A microbiologist is comparing two pathogens: Mycobacterium tuberculosis, a bacterium about 3 µm long, and the Human Immunodeficiency Virus (HIV), a virus about 120 nm across.State two structural differences between Mycobacterium tuberculosis and HIV.2 marks
- A patient has had a persistent cough, fever, night sweats and weight loss for several weeks. Tests show that she is infected with Mycobacterium tuberculosis. The bacteria entered her lungs and were engulfed by macrophages in the alveoli, but many of the bacteria were not destroyed.Suggest how untreated tuberculosis could eventually lead to the death of the patient.2 marks
- HIV has a lipid envelope containing attachment proteins, a protein capsid, two single-stranded RNA molecules and the enzyme reverse transcriptase. It infects helper T cells, which have CD4 receptors on their surface.Describe how HIV enters a helper T cell and how its genetic material is used to produce viral DNA.3 marks
Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).