AQA GCSE triple higher biology topic 3 - infection and response

Pathogen

Microorganism that causes disease.

Bacterial pathogen

Bacteria can reproduce rapidly and may release toxins that damage tissues.

Viral pathogen

Viruses reproduce inside host cells and can damage them.

Fungal pathogen

Fungi can grow on or inside organisms and cause disease.

Protist pathogen

Single

Salmonella

Bacterial pathogen causing food poisoning, fever, abdominal cramps and diarrhoea.

Gonorrhoea

Sexually transmitted bacterial infection that can cause painful urination and discharge.

HIV

Virus that attacks immune cells and can lead to AIDS if untreated.

AIDS

Condition in which HIV has severely damaged the immune system.

Measles

Viral disease causing fever and a red skin rash.

Tobacco mosaic virus

Plant virus causing mosaic leaf discolouration and reducing photosynthesis.

Rose black spot

Fungal plant disease causing dark leaf spots and reduced photosynthesis.

Malaria

Disease caused by a protist and transmitted by mosquitoes.

Physical and chemical defences

Skin, mucus, cilia, nose hairs and stomach acid help prevent infection.

Phagocytosis

White blood cells engulf and digest pathogens.

Antigen

Molecule that triggers a specific immune response.

Antibody

Protein that binds specifically to an antigen on a pathogen.

Antitoxin

Substance produced by immune cells that neutralises toxins released by pathogens.

Memory cell

Long

Vaccination

Introduces pathogen antigens or their instructions to stimulate immunity and memory cell formation.

Herd immunity

High population immunity reduces transmission and indirectly protects vulnerable people.

Antibiotics

Medicines that kill bacteria or stop their growth; they do not work against viruses.

Antibiotic resistance

Inherited ability of some bacteria to survive an antibiotic, allowing them to reproduce and spread.

Antiseptic

Substance used on living tissue to kill or inhibit microorganisms.

Disinfectant

Substance used on surfaces to kill or inhibit microorganisms.

Painkiller

Medicine that relieves symptoms such as pain without necessarily treating the cause.

Clinical trial

Test of a treatment in humans to assess safety, dose and effectiveness.

Placebo

Inactive treatment used as a comparison in a trial.

Double

blind trial

Toxicity

Degree to which a substance causes harm.

Efficacy

How well a treatment works.