Monitoring & Maintaining Health (OCR GCSE Combined Science A (Gateway): Biology): Flashcards

HPV infects cells of the cervix and can trigger cervical cancer, so it increases the risk of developing it.

By vaccination against HPV, given before people become sexually active.

Severe illness can lead to depression, which in turn can weaken the immune system and worsen physical health.

Diet, stress and a person's life situation, including income and access to healthcare.

A disease that can be passed from person to person is described as communicable.

HIV destroys lymphocytes, the white blood cells that make antibodies.

False.

Cancer is non-communicable. Some viruses, such as HPV, can increase the risk of developing it.

False.

Health also depends on mental and social well-being, not just the absence of disease.

A microorganism that causes disease in another organism.

Viruses, bacteria, protists and fungi.

They reproduce very quickly and release toxins that damage cells.

Tuberculosis, caused by Mycobacterium tuberculosis.

Cholera and bacterial meningitis are others.

Athlete's foot.

Malaria, caused by Plasmodium falciparum.

Tobacco mosaic virus (TMV).

Barley powdery mildew, caused by Erysiphe graminis.

Crown gall disease, caused by Agrobacterium tumefaciens.

Through water, through the air, by direct contact, and in body fluids.

Ingestion, animal vectors and the soil are others.

By an animal vector — the mosquito.

Through body fluids — during sexual contact, by sharing needles, or from parent to infant in breast milk.

Through the soil.

Good personal hygiene, such as handwashing.

Self-isolating when sick.

Being vaccinated.

It allows early diagnosis, so an infected person can be treated or isolated before infecting others.

It can detect alleles that indicate a person is likely to develop a disease later, so they can prepare or change their lifestyle.

Spotting the early signs allows quick treatment, before the disease has developed too far.

Crowded housing, poor sanitation, poor diet and limited healthcare all make disease spread more easily.

All viruses are pathogenic, because they can only reproduce inside living cells.

Malaria is caused by a protist, a type of single-celled eukaryotic pathogen.

False.

Only a small minority are pathogenic. Most are harmless or useful.

True.

In plants they can be very serious and threaten whole crops.

Lymphocytes and phagocytes.

It carries out phagocytosis — engulfing and digesting pathogens.

Its sensitive membrane detects chemicals given off by the pathogen.

It then engulfs the pathogen and releases digestive enzymes to break it down.

Its multi-lobed nucleus lets it change shape easily as it chases and engulfs pathogens.

It produces antibodies to destroy pathogens and antitoxins to neutralise the toxins they release.

It has well-developed cell machinery, such as many ribosomes, so large numbers of antibodies can be made quickly.

By its large, round nucleus that fills nearly the whole cell, and its clear cytoplasm.

They produce marker molecules so phagocytes recognise pathogens as foreign.

They make pathogens stick together, making phagocytosis more effective.

A fragment of a cell in the blood that is involved in clotting and forming scabs.

Platelets release chemicals that turn soluble fibrinogen into insoluble fibrin.

The fibrin forms a mesh across the wound, trapping red blood cells to make a clot.

It prevents further blood loss from the wound.

The scab seals the wound, stopping microorganisms getting in.

Until new skin has grown underneath it, sealing the skin again.

Platelets cause soluble fibrinogen to be converted into insoluble fibrin.

The process by which a phagocyte engulfs and digests a pathogen is called phagocytosis.

False.

They are fragments of cells.

True.

Despite the small number, they are essential to the immune system.

They act in the same way against all types of pathogen, rather than targeting one.

Physical barriers and chemical barriers.

It covers the body, forming a barrier pathogens cannot easily cross.

If cut, it heals itself, often by forming a scab.

They trap pathogens in the air, stopping them being breathed down into the lungs.

Mucus traps pathogens in the trachea and bronchi.

Cilia waft the mucus up to the back of the throat, where it is swallowed or coughed out.

It contains hydrochloric acid, strong enough to kill pathogens that are swallowed in food, drink or mucus.

They are enzymes that break down and kill bacteria on the surface of the eye.

It kills bacterial and fungal pathogens on the skin surface.

Harmless bacteria in the gut outcompete pathogenic bacteria, so the pathogens cannot establish themselves.

It breaks the physical barrier, giving pathogens a direct route into the body.

Stomach acid is a chemical barrier.

Skin is a physical barrier.

Cilia in the trachea waft mucus and trapped pathogens up to the throat.

Tears contain enzymes called lysozymes that kill bacteria on the eye.

False.

They work against all pathogens in the same way. Only the immune system is specific.

True.

It traps pathogens in the airways before they can reach the lungs.

A molecule found on the surface of a cell that the immune system can recognise as foreign.

A Y-shaped protein made by lymphocytes, with a shape complementary to one specific antigen.

A protein made by lymphocytes that neutralises the toxins released by bacteria.

Each antibody fits only one type of antigen, so it acts against that pathogen alone.

Phagocytes engulf and digest any pathogen in the same way.

The clumping together of pathogens by antibodies, so they cannot move easily and are engulfed more readily.

A lymphocyte recognises the antigen and produces a specific antibody.

It clones itself so millions of copies make that antibody, which agglutinates the pathogens for phagocytes to destroy.

So that large quantities of the correct antibody can be produced quickly.

A lymphocyte that remains in the blood after an infection and recognises that pathogen if it returns.

Memory cells already recognise the antigen, so they make large amounts of the right antibody very quickly.

The secondary response destroys the pathogen before it can multiply enough to cause symptoms.

They clump the pathogens together and release chemicals that signal to phagocytes which cells to destroy.

Antibodies are produced by white blood cells called lymphocytes.

The shape of an antibody is complementary to the antigen it acts against.

False.

Antibodies are proteins made by your own lymphocytes. Antibiotics are medicines that kill bacteria.

False.

Each antibody is specific to one antigen, so it works against only that pathogen.

A preparation containing a harmless version of a pathogen, or its antigens, used to induce immunity.

Killing it.

Making it unable to grow or divide.

Using only fragments that carry the antigens.

The antigens in the vaccine trigger lymphocytes to make specific antibodies.

Memory cells remain, so a real infection meets a fast, large response.

The response is so fast and large that the pathogen cannot multiply enough to cause symptoms.

Orally, nasally, or by injection.

When enough of a population is vaccinated that an unvaccinated person is unlikely to be infected.

It protects people who cannot be vaccinated, because the disease cannot spread easily through the population.

Cases rise again, as happened with measles when global vaccination rates dropped.

Bacterial infections only. They do not work against viruses or fungi.

Penicillin.

They act against viruses, usually by slowing the rate at which the virus reproduces.

Viruses reproduce inside host cells, so damaging the virus risks damaging the body's own cells.

A substance that kills microorganisms outside the body — on the skin to clean wounds, or on surfaces.

It would be toxic to the body's own cells.

Vaccinating a large proportion of a population produces herd immunity.

Memory cells left in the blood after vaccination allow a fast response to future infection.

False.

Antibiotics work only on bacteria. Viral infections need antiviral drugs.

False.

It contains a harmless version — killed, unable to divide, or just fragments carrying the antigens.

Plants and microorganisms.

The foxglove.

Willow.

In the Penicillium mould, a fungus, by Alexander Fleming.

They are synthesised by chemists, often using computer modelling to identify candidate molecules — though the starting point may still be a plant chemical.

Toxicity — does it have harmful side effects?

Efficacy — does it work?

Dose — what is the lowest effective dose?

The drug is tested in the laboratory on cells and tissues, and then on live animals.

To see its effect on a whole organism, including toxicity and dosage, before people are exposed to it.

Healthy volunteers first, and then patients with the condition.

To check the drug is safe in a normally functioning body before larger doses are tried.

A treatment with no active drug in it, given for comparison during a trial.

Neither the patient nor the doctor treating them knows who is receiving the active drug and who the placebo.

They remove bias, so a doctor cannot unintentionally influence a patient or the way results are judged.

They are peer-reviewed, so other scientists check they are accurate, and then published in journals.

Preclinical testing on cells and tissues.

Testing on whole animals.

Clinical trials on healthy volunteers and then patients.

Testing whether a drug actually works is testing its efficacy.

Testing on cells and tissues before any human trials is called preclinical testing.

False.

Healthy volunteers are tested first, to check the drug is safe in a normally working body.

True.

The drug is tested on cells, tissues and animals before clinical trials on people begin.

The interaction of a number of factors, rather than any single cause.

Cardiovascular disease, many cancers, some lung diseases such as bronchitis, and some liver diseases such as cirrhosis.

Diseases influenced by nutrition, including type 2 diabetes, are a fifth.

Disease of the heart and its blood vessels.

Fatty plaques build up in the coronary arteries, narrowing them and making them less elastic.

This restricts blood flow to the heart muscle.

Angina is chest pain from a partly blocked coronary artery.

A heart attack follows a complete blockage, so that part of the heart muscle cannot respire or contract.

Smoking, a poor diet, lack of exercise and high alcohol consumption.

It raises the likelihood of the disease but does not guarantee it — a correlation is not the same as causation.

Stopping smoking, eating less animal fat, and exercising regularly to lower blood pressure and cholesterol.

Daily aspirin, which reduces the risk of blood clots forming in the arteries.

A balloon is threaded to the blocked vessel and inflated, flattening the plaque.

A stent is left in place to hold the artery open.

A blood vessel taken from elsewhere in the body is used to create a new route for blood around the blocked section.

Donor hearts are in short supply and can be rejected by the immune system.

The patient may need lifelong drugs that leave them prone to infection.

Chemicals in smoke damage the arteries, and a diet high in saturated fat and cholesterol builds plaques in the damaged areas.

Taking in more energy than is used.

It raises the risk of type 2 diabetes and cardiovascular disease.

Alcohol consumption.

Smoking, along with air pollution and heavy dust exposure.

The result of changes in cells that lead to uncontrolled growth and division, which can form a tumour.

Carcinogens — cancer-causing chemicals — and radiation, such as UV light.

They have no useful function but still consume resources such as glucose and oxygen.

It shows how the incidence of non-communicable disease varies between places, which helps target health advice and policy.

Fatty deposits that build up in an artery wall are called plaques.

A clump of cells produced by uncontrolled cell division is called a tumour.

False.

It is a risk factor: it greatly raises the likelihood, but does not guarantee the disease.

False.

They result from a number of interacting factors.

By growing new tissue from stem cells and using it to repair or replace the damaged part.

They can differentiate into most types of specialised cell, so they could replace many different tissues.

Diabetes and paralysis.

They can differentiate into only a few cell types, mainly blood cells.

When the patient's immune system attacks transplanted tissue because it recognises it as foreign.

An embryo is created with the same genes as the patient, so the stem cells are not recognised as foreign.

The patient does not need drugs to suppress their immune system, which would leave them open to infection.

Many people regard an embryo as a human life, so destroying one to obtain stem cells is unacceptable to them.

Eggs are hard to obtain — the donor must undergo hormone therapy and an operation to collect them.

Tissue grown from their own genetic information would not be rejected, unlike a donor organ.

The long-term effects are not fully known, as the technology is still relatively new.

In therapeutic cloning an embryo is produced with the same genes as the patient.

Transplanted tissue may be attacked by the immune system in a process called rejection.

False.

They carry the same genes, so the immune system does not treat them as foreign.

False.

Adult stem cells do not require an embryo, so the main ethical objection does not apply.

An international effort, completed in 2003, to determine the entire DNA sequence of the human genome.

Predicting and preventing disease.

Testing and treating inherited disorders.

Developing new and improved medicines.

Knowing which genes make a person more likely to develop a disease allows doctors to warn them and advise on lifestyle and diet.

Faulty alleles, such as those causing cystic fibrosis, can be identified quickly, so people can be tested and treatments developed.

Medicines designed for people with particular genetic variations, so the drug works better and causes fewer side effects.

Doctors can better predict how well a drug will work for a particular person, and choose an effective dose.

Being told they are likely to develop a disease can cause anxiety and stress — possibly needlessly, as they may never develop it.

They might refuse to hire someone thought likely to become ill.

They could make life insurance far more expensive, or refuse it altogether, for someone likely to develop a serious disease.

People carrying a faulty allele could be pressured not to have children, even where they are healthy themselves.

It allows early treatment or screening, and gives the person time to change their lifestyle.

The spec asks you to weigh both benefits and risks, including practical and ethical considerations.

The Human Genome Project determined the entire DNA sequence of human beings.

Being unfairly treated because of your genes is known as genetic discrimination.

False.

It raises the likelihood only — many people carrying such an allele never develop the disease.

True.

Drugs can be targeted to a person's genetic variations, improving how well they work and reducing side effects.