Describe some common infections, including: a cholera (bacteria) causes…

The idea

Each named infection must be linked to its pathogen group and its effect on the host. Cholera is caused by bacteria and causes diarrhoea. Tuberculosis is caused by bacteria and damages the lungs. Chalara ash dieback is caused by fungi and causes leaf loss and bark lesions in ash trees. Malaria is caused by protists and damages blood and liver. HIV is a virus that destroys white blood cells, leading to the onset of AIDS. Stomach ulcers can be caused by Helicobacter bacteria. Ebola is a virus that causes haemorrhagic fever. A multiple-choice question may give an infection and ask for the pathogen group, or give an effect and ask for the infection. Match both the group and the effect before selecting.

What earns the marks

• Cholera is caused by bacteria and causes diarrhoea.
• Tuberculosis is caused by bacteria and causes lung damage.
• Chalara ash dieback is caused by fungi and causes leaf loss and bark lesions.
• Malaria is caused by protists and causes damage to blood and liver.
• HIV is a virus that destroys white blood cells, leading to the onset of AIDS.
• Stomach ulcers can be caused by Helicobacter bacteria.
• Ebola is a virus that causes haemorrhagic fever.

Common mistakes and how to put them right

• Mixing up pathogen groups, for example treating malaria as bacterial.

  Put it right: Malaria is caused by protists.

• Confusing HIV with AIDS.

  Put it right: HIV is the virus, and AIDS is the condition that develops after white blood cells are destroyed.

• Forgetting that Chalara ash dieback affects plants.

  Put it right: It is a fungal infection of ash trees causing leaf loss and bark lesions.

Exam tips

• Make a quick table linking each infection to its pathogen group and its effect before answering.
• Check both parts of an option: the pathogen group and the described effect must both be correct.
• Watch for options that swap effects between infections, such as linking cholera to lung damage.