AQA Biology GCSE Topic 3: Infection and Response

Comprehensive vocabulary flashcards covering pathogens, human and plant diseases, immune systems, drug development, and monoclonal antibodies based on AQA Biology GCSE Topic 3 notes.

Pathogens

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

Binary fission

The process by which bacteria multiply very quickly by dividing into two.

Toxins

Substances produced by bacteria that can cause damage to cells and make an individual feel ill.

Protists

A type of microorganism, some of which are parasitic and use humans or animals as hosts to cause damage.

Hyphae

Thread-like structures that make up the body of some types of fungi and can produce spores.

Droplet infection

A method of spreading pathogens through the air when sneezing, coughing, or talking expels droplets that others breathe in.

Vaccination

The process of injecting a small amount of a harmless pathogen into an individual to provide immunity and limit spread.

Measles

A viral disease spread by droplet infection, characterized by fever and a red skin rash.

HIV

A virus spread by sexual contact or exchange of bodily fluids that attacks the immune system and can lead to AIDS.

AIDS

A state resulting from HIV infection where the body's immune system is so damaged it is susceptible to many different diseases.

Antiretroviral drugs

Medicines used to stop the HIV virus from replicating in the body to prevent the development of AIDS.

Tobacco mosaic virus (TMV)

A plant pathogen causing leaf discolouration which prevents photosynthesis and reduces crop yield.

Salmonella

Bacterial food poisoning often found in raw meat and eggs, caused by toxins secreted by bacteria in the animal's gut.

Gonorrhoea

A sexually transmitted disease (STD) with symptoms of thick yellow or green discharge and pain during urination.

Rose black spot

A fungal disease of roses where purple or black spots develop on leaves, causing them to turn yellow and drop early.

Malaria

A disease caused by protist pathogens that enter red blood cells, spread by the vector of the female Anopheles mosquito.

Vector

An organism, such as the female Anopheles mosquito, that carries and transmits a pathogen from one host to another.

Skin flora

Good microorganisms on the skin that compete with bad microorganisms for space and nutrients to protect the body.

Cilia

Hair-like structures on cells in the trachea and bronchi that beat to waft mucus upwards to be swallowed.

Phagocytosis

The process by which white blood cells protect the body by engulfing and consuming pathogens.

Antigen

A structure on the surface of a pathogen that a specific complementary antibody binds to.

Antibodies

Proteins produced by white blood cells that bind to antigens on pathogens, causing them to clump together.

Antitoxins

Substances produced by white blood cells that neutralise the toxins released by pathogens.

Herd immunity

The protection given to a population when a large proportion are immune, reducing the overall spread of a pathogen.

Antibiotics

Medicines, such as Penicillin, that kill bacterial pathogens inside the body without damaging body cells.

Efficacy

A measure of how well a drug carries out its intended role, tested during drug development.

Preclinical testing

The stage of drug development using cells, tissues, and live animals to test for toxicity and efficacy.

Clinical trials

Testing of new drugs on healthy volunteers and patients to find the most effective dose and check for side effects.

Placebo

A substance used in clinical trials that looks like the real drug but contains no active ingredient.

Double-blind trial

A trial where neither the patient nor the doctor knows who is receiving the active drug versus the placebo to remove bias.

Monoclonal antibodies

Identical antibodies produced from the same immune cell that are designed to bind to only one specific protein antigen.

Hybridoma

A cell created by combining a mouse lymphocyte with a tumour cell, which can divide rapidly to produce monoclonal antibodies.

Human chorionic gonadotrophin ($hCG$)

A hormone present in the urine of pregnant women which is targeted by monoclonal antibodies in pregnancy tests.

Tumour markers

Specific antigens on the cell membranes of cancer cells that are not found on normal body cells.

Chlorosis

A yellowing of plant leaves caused by a magnesium deficiency, which results in a lack of chlorophyll.

Waxy cuticle

A physical plant defence that acts as a barrier to stop microorganisms from entering the leaves.

Mimicry

A mechanical plant defence where plants trick animals, such as by appearing like unhealthy plants or having patterns like butterfly eggs.