echoesof.science · Ages 15–16
Innate and adaptive immunity
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the game and the quiz
echoesof.science/school/immune-system/ages-15-16/
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Innate immunity is non-specific and present before any infection. It includes barriers (skin keratin, mucus, enzymes in tears and saliva, stomach acid), phagocytes, natural killer cells, inflammation and fever, which inhibits pathogen growth.
Phagocytes such as neutrophils, macrophages and dendritic cells engulf pathogens; lysosomes digest them. Neutrophils make up about 50–60% of white blood cells. Dendritic cells then present antigens on their surface, triggering adaptive immunity.
An antigen is a molecule that stimulates an immune response. B lymphocytes mature in the bone marrow and T lymphocytes in the thymus. A person has hundreds of millions of different B cells, each recognising a different antigen.
Experiment: Does scrubbing time matter?
- Agree a fixed amount of cream-and-glitter (for example one pea-sized blob) and rub it evenly over both hands.
- Count the glitter specks in three marked 1 cm squares on the back of one hand. Take the mean as the 'before' value.
- Wash with soap and water for a set time: 0 s (rinse only), 5 s, 10 s or 20 s of scrubbing. Each group tests one time; keep water flow and soap volume the same.
- Dry gently and count the specks in the same three squares again.
- Calculate the percentage removed = (before − after) ÷ before × 100. Pool class results, find the mean and range for each time, and plot % removed against scrub time.
| Scrub time (s) | Mean specks before | Mean specks after | % removed |
|---|---|---|---|
| 0 (rinse only) | Sketch the graph you expect: is the increase in % removed straight or does it level off? | ||
| 5 | Sketch the graph you expect: is the increase in % removed straight or does it level off? | ||
| 10 | Sketch the graph you expect: is the increase in % removed straight or does it level off? | ||
| 20 | Sketch the graph you expect: is the increase in % removed straight or does it level off? |
Questions
Describe what happens from the moment a bacterium enters a cut to the production of antibodies. Use: phagocyte, antigen, B cell, plasma cell.
Sketch and label a graph of antibody level against time for a first and a second exposure to the same antigen.
🍎Use your class results to describe the effect of scrubbing time on % glitter removed. Quote means and ranges.
Give two limitations of using glitter as a model for microbes, and one improvement to your method.
Sources for every fact on this sheet: echoesof.science/school/immune-system/sources/