AQA Biology GCSE Topic 3: Infection and Response Notes

Flashcards for AQA Biology GCSE Topic 3: Infection and Response

Pathogens

Microorganisms that cause infectious disease, including viruses, bacteria, protists, and fungi.

Viruses

Very small pathogens that move into cells and use the cell's biochemistry to make copies of itself, leading to cell bursting and the release of copies into the bloodstream.

Bacteria

Small pathogens that multiply quickly through binary fission and produce toxins that can damage cells.

Protists

Pathogens that are sometimes parasitic, using humans and animals as their hosts and causing damage.

Fungi

Pathogens that can be single-celled or have a body made of hyphae and can produce spores to spread to other organisms.

Direct Contact

Touching contaminated surfaces

By Water

Drinking or coming into contact with dirty water.

By Air

Pathogens carried in the air and breathed in, such as through droplet infection.

Improving Hygiene

Hand washing, using disinfectants, isolating raw meat, using tissues when sneezing.

Removing Vectors

Using pesticides/insecticides, removing vector habitats.

Vaccination

Injecting a small amount of a harmless pathogen to induce immunity.

Measles

Fever and red skin rash; prevented by vaccinations.

HIV

Attacks the immune system, leading to AIDS; spread by sexual contact/bodily fluids.

Tobacco mosaic virus

Discoloration of leaves, reduces yield; spread by contact or insects.

Salmonella

Food poisoning caused by bacteria in raw meat and eggs.

Gonorrhoea

Thick discharge from the vagina or penis, pain when urinating; spread through sexual contact.

Rose black spot

Purple or black spots on rose leaves, reduces photosynthesis; spores spread by water or wind.

Malaria

Fevers and shaking; spread by the female Anopheles mosquito.

The skin

Acts as a physical barrier, produces antimicrobial secretions, and has skin flora.

The nose

Has hairs and mucus to prevent particles from entering the lungs.

The trachea and bronchi

They secrete mucus to trap pathogens, and cilia waft mucus upwards.

The stomach

Produces hydrochloric acid to kill pathogens.

Phagocytosis

Engulfing and consuming pathogens

Antigen

Structures on pathogens to which specific antibodies bind.

Antitoxins

Neutralize toxins released by pathogens.

Vaccination

Making an individual immune to a disease before infection.

Antibiotics

Medicines that kill bacterial pathogens without damaging body cells.

Painkillers

Treat the symptoms of a disease, not the cause.

Antibiotic resistance

The ability of bacteria to no longer be killed by antibiotics due to mutations.

Preclinical Testing and Clinical Trials

Testing for toxicity, efficacy, and dose of new drugs.

Aspirin

Used as a painkiller and originates from willow.

Digitalis

Used to treat heart problems and originates from foxgloves.

Penicillin

A substance produced by Penicillium mould that kills bacteria.

Monoclonal Antibodies

Identical antibodies produced from the same immune cell.

Human Chorionic Gonadotrophin (hCG)

A hormone present in the urine of pregnant women.

Tumour Markers

Antigens on cancer cell membranes that are not found on normal body cells.

Signs of Plant Diseases

Stunted growth, spots on leaves, areas of decay, abnormal growths, malformed stems/leaves, discoloration, pests on leaves.

Nitrate deficiency

Can stunt growth in plants.

Magnesium deficiency

Can cause chlorosis in plants.

Physical defences of plants

Tough waxy cuticle and cellulose cell walls.

Chemical defences of plants

Poisons and antibacterial compounds.

Mechanical defences of plants

Thorns, hairs, drooping leaves, and mimicry.