State that not all bacteria have harmful effects e.g. probiotics:

Not all bacteria have harmful effects. Good bacteria (probiotics) are single-celled bacteria that contribute to our health by protecting us from harmful microorganisms as well as help in the digestion of food. Probiotics help to balance the gut microflora and further support the immune system.

Outline the ways our body prevents the entry of pathogens:

In order for a pathogen to get access to our body, they have to pass through barriers the body creates such as:

  • Nose hairs
  • Sticky mucus covering our eyes, mouth, and nose
  • Stomach acid

Define: pathogen, parasite, host, budding, asexual reproduction:


An organism, such as bacteria, fungi, virus or parasite that causes diseases in their host.


An organism or virus that lives in or on another organism (the host) and gets nutrients and other benefits at the expense of the host’s well-being. 


An organism on or in which a parasite lives

A type of asexual reproduction in which a new individual or branch develops from an outgrowth on the body of the organism.

Asexual reproduction:

Reproduction not involving gametes or fertilisation. 

List the types of pathogens and give specific examples of each:
Some famous types of pathogens include Bacteria (e.g. Salmonella), Fungi (e.g. Aspergillus Flavus), Virus (e.g. SARS-CoV-2: COVID-19), and Parasite (Giardia)

Summarise methods in how viruses replicate:

Viruses replicate in 5 steps:

  1. Attachment:
    The virus uses its external proteins to latch onto a target cell by attaching to membrane proteins on the surface of the host cell.
  2. Entry:
    Either the entire virus enters the cell or injects its nucleic acid into the cell.
  3. Replication:
    The virus or the nucleic acid takes over the cell’s nucleus and protein synthesis system (ribosomes). New viral proteins and new copies of DNA or RNA are made.
  4. Assembly:
    The new DNA or RNA and viral proteins are put together in their correct positions to make new viruses.
  5. Release:
    New viruses are released from the cell by either budding out through the cell membrane or by causing the cell to burst.

State that toxins produced by pathogenic bacteria cause cell damage/ illness

Bacteria multiply quickly inside the body and release toxins and waste products that damage tissue. These toxins then enter the bloodstream and spread to the rest of the body, causing cell damage and symptoms of illness.