Multicellular organisms rely on efficient transport systems to distribute essential substances and defend against pathogens. In humans, the circulatory system uses blood to perform these transport and defense roles.
The table names some components of blood. Complete the table by giving the missing function or cell type for each component.
| Component of blood | Function | Cell type |
|---|---|---|
| phagocyte | (i) | (ii) |
| lymphocyte | produces antibodies / antitoxins | (iii) |
| plasma | (iv) | non-cellular (liquid) |
Suggest the physiological consequences to the body of having an abnormally low concentration of platelets in the blood.
A person is infected with a pathogen, recovers, and is later exposed to the same pathogen again. Explain how memory cells in the blood provide a rapid response during this secondary exposure.
