Describe some of the symptoms caused by pathogens

  • Different pathogens have different specific requirements for their ideal living conditions which can be found in different parts of the body. For example, the lungs, intestines, or inside of the ear.
  • Depending on where the pathogen is residing, the symptoms one will experience from the infection would result from the damage/dead cells that the pathogen damaged.
  • The immune system can also cause symptoms in its attempt to regain a balance of healthy body cells to pathogen cells- a balance lost when pathogens enter the body and start to grow and reproduce.
  • The body makes automatic adjustments or changes in order to try and re-establish balance when different factors cause an imbalance to maintain homeostasis.
  • Symptoms are caused when the body will try to damage, kill, or get rid of pathogens by creating a less appealing living environment for them (such as wrong temperature or poor nutrient sourcing).

Distinguish between antibodies, antibiotics, antigens, and vaccinations:

Proteins produced by the immune system that target and help to destroy specific pathogens.


Compounds produced by some microorganisms selectively inhibit or kill other microorganisms. An antibiotic medicine prevents or stops the growth and spread of bacteria.


Any substance that causes your immune system to produce antibodies against a pathogen.


A substance was given to possible host organisms, such as humans, or other large animals that contain elements of a pathogen in order to stimulate the recipient’s immune system to produce antibodies to protect the person/animal from possible future infection.

Outline how Alexander Fleming discovered the first antibiotic:

  • Fleming went on holiday and left Petri dishes of staphylococcus colonies.
  • When he returned, he observed that a mold grew in one of them, which inhibited the growth of the bacteria.
    • That was because the mold secreted something which prohibited the growth of that specific bacteria.
  • The mold must have somehow entered the petri dish.
  • This was the first major step for the first antibiotic to be made.

Summarise Edward Jenner’s approach to developing a vaccine:

The steps were taken by Edward Jenner to create vaccination, the first vaccine for smallpox. Jenner did this by inoculating James Phipps with cowpox, a virus similar to smallpox, to create immunity, unlike variolation, which used smallpox to create an immunity to itself.

Define the terms herd immunity, epidemic:

Herd immunity:

Resistance to the spread of an infectious disease within a population that is based on pre-existing immunity of a high proportion of individuals as a result of previous infection or vaccination.


A widespread occurrence of an infectious disease in a community at a particular time.

Suggest how bacteria have become evolved to become resistant to antibiotics

  • The bacteria that are resistant to antibiotics contain the gene MCR-1 found in plasmids.
    • Plasmids are tiny pieces of DNA that can be shared with not only members of their species, but any bacteria.
  • Through the overuse of antibiotics, the gene which causes resistance has become more wide-spread, especially considering it is found in plasmids