Immune SystemOxford AQA IGCSE Biology: Subtopic test

1. 1
   A nurse at a clinic in Sharjah is explaining to a patient why a small cut on their finger healed cleanly without becoming infected, even though the skin was broken and pathogens were present on the surrounding surfaces.

   (a)

   Which of the following is NOT one of the body's non-specific defences against pathogens?

   [1 mark]

   • AMucus lining the airways
   • BStomach acid
   • CAntibody production by lymphocytes
   • DSkin acting as a physical barrier

   (b)

   Which structures work together to trap and remove pathogens from the airways before they reach the lungs?

   [1 mark]

   • ACilia and mucus
   • BPhagocytes and lymphocytes
   • CAntibodies and antigens
   • DMemory cells and vaccines

   (c)

   A few pathogens managed to enter the patient's bloodstream through the cut. Explain how phagocytes destroyed these pathogens.

   [2 marks]

   Total for question 1: 4 marks

2. 2
   A school in the UAE runs a vaccination programme against a viral disease. Several years later, when a student who was vaccinated is exposed to the same virus, they show no symptoms of illness.

   (a)

   During a school vaccination programme, students are given an injection containing a weakened form of a pathogen. What does this injection introduce into the body to stimulate immunity?

   [1 mark]

   • AAntibiotics
   • BAntigens
   • CGlucagon
   • DPlatelets

   (b)

   Which cells are responsible for the rapid, large-scale antibody production seen when the vaccinated student meets the same pathogen again years later?

   [1 mark]

   • ARed blood cells
   • BCiliated epithelial cells
   • CRoot hair cells
   • DMemory cells

   (c)

   A few parents at the school were hesitant about vaccination but were told that high vaccination rates protect even unvaccinated students. Explain how herd immunity protects people who are not vaccinated.

   [2 marks]

   Total for question 2: 4 marks

3. 3
   A museum exhibit describes the accidental discovery of penicillin by Alexander Fleming in 1928, when he found that a contaminating mould had killed the bacteria growing on a laboratory culture plate. The exhibit also notes that some bacteria today are resistant to antibiotics like penicillin.

   (a)

   In 1928, Alexander Fleming noticed that a mould called Penicillium had contaminated one of his bacterial culture plates, and that bacteria could not grow in the area around the mould. Describe how this observation led to the discovery of penicillin and explain its historical significance.

   [3 marks]

   (b)

   Explain why antibiotics such as penicillin cannot be used to treat viral infections such as the common cold, and explain how bacteria have since evolved resistance to antibiotics like penicillin.

   [4 marks]

   Total for question 3: 7 marks

4. 4
   A pharmaceutical company in the UAE has developed a new drug for a chronic disease and must test it thoroughly before it can be prescribed. Separately, health authorities are running a public awareness campaign encouraging parents to vaccinate their children, as some parents remain concerned about vaccine safety.

   (a)

   A pharmaceutical company has developed a new drug to treat a chronic disease. Describe the stages involved in testing this new drug before it can be prescribed to patients, including the purpose of using a placebo and a double-blind trial.

   [6 marks]

   (b)

   Evaluate the benefits and risks of a national childhood vaccination programme, including the concept of herd immunity, to explain why health authorities encourage high vaccination rates.

   [6 marks]

   Total for question 4: 12 marks

End of questions