Key Area 5

(d) Immune evasion

Parasites have evolved ways of evading the immune system. Flick through the image carousel to find out the tricks they have up their wee parasitic sleeves!

Antigenic variation allows many parasites to change surface antigens. This allows the parasite to evade the immune system as the new surface antigens are not recognised by the immune system. This is the case with seasonal 'flu.

Vaccination is the answer to controlling most virus-induced diseases. But how do they work?

Task 75 - consolidation

Use these questions from SCHOLAR to consolidate your learning on the immune system.

  1. Complete the table using the statements listed.

2. During phagocytosis, special organelles release digestive _____________ into the vacuole containing the parasite.

3. What are the special organelles from the previous question known as?

4. In response to parasitic attack, lymphocytes are amplified through mitosis. What is this cellular response known as?

5. The role of T lymphocytes in immune response is in:

a. Phagocytosis

b. Clonal selection

c. Production of specific antibodies

d. Apoptosis of specific damaged cells


6. Which of the following best describes how endoparasites evade destruction?

a. Mimics host antigen

b. Mimics other parasites

c. Kills lymphocytes

d. Kills phagocytes


7. Due to antigenic variation, last season's flu vaccine _________ be effective against this season's strain.

a. will

b. will not


8. NHS Scotland plans to vaccinate preschool children against mumps, measles and rubella using the MMR vaccination. Some parents are reluctant to vaccinate, being aware that if enough other children get vaccinated, their child will receive some protection anyway. What is the ability to receive some protection even without having being vaccinated known as?


9. What is the study of outbreaks and spread of disease called?


Click here for the answers to these questions.

Time to get serious...one more wee mini, teeny-tiny sub-section to go. Can you believe we've nearly completed AH Biology?! It's time...click to move onto Key Area 5f on Challenges in treatment & control.