Edexcel GCSE Combined Science Biology Topic 5

cause

A factor that, when it changes, makes something else change.

communicable disease

A disease caused by a pathogen that can be passed from an infected individual to others. Also called an infectious disease.

correlation

When two factors change in a similar pattern, we say they are correlated.

disease

Something that causes the body not to work properly.

health

A state of complete physical, social and mental well- being.

immune system

The system that helps protect the body from harm by diseases, especially communicable diseases.

lifestyle

The way we live, such as our diet, whether we smoke tobacco, and how much exercise we take. Lifestyle can affect whether we develop some diseases.

non-communicable disease

A disease that cannot be passed from individuals to those around them. Examples include inherited diseases and some diseases caused by lifestyle.

pathogen

A microorganism that causes a communicable disease.

cirrhosis

A disease of the liver, often caused by drinking a large amount of ethanol (alcohol) over a long period of time.

deficiency disease

A disease caused by a lack of a particular nutrient in the body, such as anaemia caused by a lack of iron.

drug

A substance that we take into the body, which affects how the body works.

genetic disorder

A disease caused by faulty alleles of our genes.

malnutrition

Health problems caused by a diet that contains too little or too much of one or more nutrients.

body mass index

An estimate of how healthy a person's mass is for their height.

cardiovascular disease

A disease in which the heart or circulatory system does not function properly.

heart attack

When the heart stops pumping properly due to a lack of oxygen reaching part of it.

obesity

A condition in which someone is overweight for their height and has a BMI above 30.

stent

A small mesh tube used to widen narrowed blood vessels and allow blood to flow more easily.

stroke

Death of brain cells caused by a lack of blood, due to a blockage in a blood vessel in the brain.

waist : hip ratio

A measure of the amount of fat in the body, calculated by dividing the waist measurement by the hip measurement.

AIDS

When HIV has damaged a person's immune system, so they are more likely to get secondary infections.

chalara dieback

A communicable disease of ash trees caused by a fungus. It produces lesions of the trunk and branches, and dieback of the top of the tree.

cholera

A communicable disease caused by a bacterium, which causes extreme diarrhoea.

diarrhoea

Loose or watery faeces.

haemorrhagic fever

A disease that includes a fever (high body temperature) and internal bleeding, such as caused by the Ebola virus.

host

An individual or species that can be infected by a certain pathogen.

HIV

A virus that attacks white blood cells in the human immune system, often leading to AIDS.

malaria

A dangerous disease, caused by a protist, that causes serious fever, headaches and vomiting and can lead to death.

protist

A kingdom of eukaryotic and mainly single-celled organisms (also called 'protoctists').

secondary infection

An infection due to the immune system being weakened previously by a different pathogen.

tuberculosis

A communicable bacterial disease that infects the lungs.

ulcer

A sore area in the stomach lining which can be caused by a bacterium.

virus

A microbe that multiplies by infecting a cell and taking over the cell's DNA copying processes. Virus particles have no cellular structure and so are not true organisms.

white blood cell

A type of blood cell that forms part of the body's defence system against disease.

epidemic

When many people over a large area are infected with the same pathogen at the same time.

hygiene

Keeping things clean, by removing or killing pathogens.

oral route

When something enters the body through the mouth.

vector

Something that transfers things from one place to another.

chemical defence

The use of chemical compounds to defend against attacks. Examples include lysozyme and hydrochloric acid.

Chlamydia

A bacterium that causes a sexually transmitted infection.

ciliated cells

A cell that lines certain tubes in the body and has cilia on its surface.

hydrochloric acid

Acid produced by cells lining the stomach, of about pH 2, which destroys many pathogens in food and drink.

lysozyme

An enzyme produced in tears, saliva and mucus, which damages pathogens.

mucus

A sticky substance secreted by cells that line many openings to the body.

physical barrier

A structure that stops something from entering a certain area. For example, the body has physical barriers, such as the skin, that stop microbes from getting inside the body.

screening

Tests on samples of body fluids to check if people have a certain condition, e.g. an STI.

sexually transmitted infection

A communicable disease that is passed from an infected person to an uninfected person during sexual activity.

activate

To make active, such as when a lymphocyte is triggered by a pathogen to start dividing rapidly.

antibody

A protein produced by lymphocytes. It attaches to a specific antigen on a microorganism and helps to destroy it.

antigen

A protein on the surface of a cell. White blood cells are able to recognise pathogens because of their antigens.

immune

When a person does not fall ill after infection, because their immune system attacks and destroys the pathogen quickly.

immunisation

Giving a vaccine that causes an immune response without the person becoming ill, and which will make the person immune to the pathogen.

lymphocyte

A type of white blood cell that produces antibodies.

memory lymphocyte

A lymphocyte that remains in the blood for a long time after an infection or vaccination.

secondary response

A much more rapid, and larger, production of antibodies to a pathogen when it infects the body again.

vaccine

A mixture containing weakened or inactive pathogens, or antigens from the pathogen. When put into the body it causes an immune response.

antibiotic

A substance that, when inside the body, either kills bacteria or stops them growing.

clinical trial

Testing of a medicine on people.

colony

A cluster of microorganisms living closely together.

dose

The total amount of something received, such as of a medicine.

inhibit

To stop or slow down a process.

penicillin

The first kind of antibiotic. It was extracted from a mould (fungus).

pre-clinical testing

Testing a drug before it is tried on humans, including testing on cells or tissues and on other animals.

resistance

When a bacterium is no longer damaged by an antibiotic.

side effect

Unintended effect of a medicine, which may be harmful.