Lesson 6.2.2

6.2.2 How TB and HIV infect human cells Quiz: Pearson Edexcel Biology A (Salters-Nuffield), Unit 6

20 questions

Written by Revision Ninja · Last reviewed 11 October 2026

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Lesson 6.2.2, How TB and HIV infect human cells: 20 multiple choice questions for the Pearson Edexcel Biology A (Salters-Nuffield) (9BI0), Unit 6: Immunity, Infection and Forensics, written with Revision Ninja.

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The 20 questions

  1. Mycobacterium tuberculosis is best described as:

    • A virus that infects helper T cells and destroys them over several months
    • A bacterium that can survive and multiply inside host macrophages
    • A protist that is transmitted by mosquitoes and infects red blood cells
    • A fungus that grows on the skin and releases toxins into the bloodstream

  2. HIV is a virus that infects which cells in the human body?

    • Neurones in the brain, which carry impulses along long axons to the muscles
    • Red blood cells, which carry haemoglobin and lack a nucleus in mature form
    • Platelets, which are fragments of megakaryocytes involved in blood clotting
    • Helper T cells, which carry the CD4 receptor on their surface

  3. How does HIV enter a helper T cell?

    • By passing through the nuclear pores of the T cell without interacting with its surface
    • By attaching to the cell wall of the T cell, which contains peptidoglycan that HIV can bind
    • By being engulfed by phagocytosis and then digesting the membrane of the T cell from inside
    • By binding its glycoprotein to CD4 and co-receptors on the cell surface, then fusing its envelope with the membrane

  4. Reverse transcriptase is an enzyme used by HIV to:

    • Make a DNA copy of its RNA genome inside the host cell
    • Break down the host cell membrane so that the virus can leave the cell by budding
    • Attach the viral envelope to the host cell membrane by forming disulfide bonds
    • Synthesise protein from its RNA using the host cell ribosomes in the cytoplasm

  5. After HIV integrates into host DNA, the infected cell can:

    • Divide by binary fission, so that the virus is copied into two new bacterial cells
    • Lose its nucleus and become a red blood cell that carries the virus in its haemoglobin
    • Produce new viral RNA and proteins
    • Stop all protein synthesis permanently, so that no further virus can be made from it

  6. Why do people with untreated HIV often develop opportunistic infections late in the disease?

    • Because HIV releases a toxin that makes the body reject all medicines given by doctors
    • Because the number of helper T cells falls
    • Because HIV causes all white blood cells to produce too much antibody, which damages the tissues
    • Because HIV makes the bacteria in the gut more dangerous, so they invade the bloodstream

  7. Tuberculosis causes symptoms partly because of the immune response to the bacteria. Which structure does the immune system form around infected macrophages?

    • A granuloma, a mass of immune cells that walls off the infection but can damage lung tissue
    • A capsid, a protein coat that encloses the bacteria and prevents any further spread
    • A biofilm, a mat of bacteria that protects the infected lung from all immune responses
    • A plasmid, a small circle of DNA that carries resistance genes to every antibiotic

  8. Which symptom of tuberculosis is most directly linked to lung infection?

    • Swelling of the lymph nodes in the neck caused by blood clots in the veins
    • A rash that spreads across the skin and fades within a single day
    • A persistent cough, sometimes producing blood-stained sputum
    • Sudden loss of hearing caused by damage to the cochlea in the inner ear

  9. Why is HIV described as a retrovirus?

    • Because it reproduces by binary fission in the same way as bacteria
    • Because it is able to infect plants and animals with equal efficiency
    • Because it uses reverse transcriptase to copy its RNA into DNA
    • Because it contains a peptidoglycan wall that is resistant to most antibiotics

  10. Which statement about HIV and TB infection is correct?

    • TB is caused by a bacterium that can be treated with antibiotics, whereas HIV is a virus that cannot be cured by antibiotics
    • TB and HIV are both viruses, so both can be cured by a single course of antibiotics
    • TB and HIV are both caused by bacteria, so both can be treated effectively with penicillin
    • HIV is a bacterium and TB is a virus, so antibiotics work against HIV but not TB

  11. Which feature of HIV allows it to evade the immune system by changing its surface?

    • The presence of a thick peptidoglycan wall that hides the viral surface from antibodies
    • The fixed capsid shape, which is identical in every virus particle and cannot be altered
    • The rapid mutation of its envelope glycoproteins
    • The use of host ribosomes to make proteins that look identical to those of the host

  12. In a lab study, the number of helper T cells in an HIV-infected patient falls from 800 to 200 per microlitre over several years. Which conclusion is best supported?

    • The patient's antibody level must have fallen to zero, because antibodies are made by helper T cells
    • The patient's red blood cell count must have risen, which indicates a successful response
    • The patient has developed complete immunity to HIV, so the virus can no longer replicate
    • The patient's immune response is weakened, making infection by opportunistic pathogens more likely

  13. Which is the best reason why TB treatment usually requires several antibiotics given over months?

    • The bacteria produce a capsid that blocks the antibiotic from reaching the cell wall in every case
    • The antibiotics only work for a few hours, so they must be taken every day for several months
    • The antibiotics must wait for the immune system to produce antibodies before they become effective
    • The bacteria can survive inside macrophages and some strains resist drugs

  14. Which process allows HIV to spread from one infected cell to another?

    • Phagocytosis of the infected cell by a neutrophil, which carries the virus to the bloodstream
    • Budding of new virus particles from the infected cell, followed by infection of neighbouring cells
    • Binary fission of the infected cell, which produces daughter cells that carry the virus
    • Spore formation within the infected cell, which allows the virus to survive outside the body

  15. Which statement evaluates the claim that HIV is easily destroyed outside the body?

    • The claim is correct, since HIV can survive indefinitely in soil and water and infects plants
    • The claim is incomplete, since HIV is fragile in the environment but is transmitted through direct contact with infected body fluids
    • The claim is correct, since HIV survives for years on surfaces and remains infectious in the air
    • The claim is incorrect, since HIV can only be transmitted by mosquitoes and never by body fluids

  16. Which of these describes the replication of HIV inside an infected cell?

    • RNA is converted to DNA, integrated into the host genome, then transcribed to make viral RNA and proteins
    • DNA is copied into RNA which is then translated directly into the capsid protein in the cell nucleus
    • The host cell divides by binary fission, and each daughter cell receives a complete viral genome
    • Peptidoglycan is synthesised and then cut into fragments that form the new virus particles

  17. Which cells in the lungs does Mycobacterium tuberculosis commonly infect and survive within?

    • Neurones in the lung tissue, which transmit signals from the diaphragm to the rest of the chest
    • Red blood cells in the alveolar capillaries, which lack a nucleus in their mature form
    • Alveolar macrophages, where it can resist destruction and multiply inside phagosomes
    • Epithelial cells in the skin, which form the outer protective barrier of the entire body

  18. Which sequence best describes the progression of untreated HIV infection?

    • A long period of immunity, then a rise in helper T cell numbers, then a short acute infection
    • Death within one week of infection, with no phase of acute infection or latency at all
    • AIDS first, then acute infection, then full clearance of the virus by the immune system
    • Acute infection, then a long period of clinical latency, then falling helper T cell counts leading to AIDS

  19. Each infected cell produces 10 new HIV particles per day. How many new particles are produced by 50 infected cells over 3 days?

    • 1,500 particles, since 10 x 50 x 3 = 1,500
    • 150 particles, since 10 x 50 = 500 and 500 divided by 3 is about 167
    • 500 particles, since 10 x 50 = 500 and the 3 days do not change the total
    • 15,000 particles, since 10 x 50 x 3 x 10 gives the total when multiplied by ten again

  20. Which evidence is the strongest indication that a person has active tuberculosis rather than latent infection?

    • A raised white blood cell count alone, which is a non-specific sign of many types of infection
    • Symptoms together with a positive sputum culture showing the bacteria are being released from the lungs
    • A positive skin or blood test with no symptoms, since this always indicates active disease
    • A clear chest X-ray taken on a single day, which proves that no bacteria are present in the body

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