Health, disease and the development of medicines flashcards: Edexcel GCSE Biology

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Health and disease

Give the WHO definition of health.: A state of complete physical, mental and social well-being and not merely the absence of disease or infirmity.
What three types of well-being does the WHO definition of health include?: Physical, mental and social.
What is a communicable disease?: A disease caused by a pathogen that can be passed from one organism to another.
What is a non-communicable disease?: A disease that cannot be passed from one person to another and is not caused by a pathogen. Example: cardiovascular disease.
How does HIV make a person more likely to get other diseases?: It destroys white blood cells, so the immune system is weakened and cannot fight other pathogens, such as the TB bacterium.
Give one other way a disease can make another disease more likely.: Damaged skin or airway lining lets pathogens in; or long-term physical illness can lead to poor mental health.
What does a correlation on a scatter diagram show, and what does it not prove?: It shows that two variables change together. It does not prove that one causes the other.

Pathogens and infections

What is a pathogen?: A disease-causing organism.
Name the four types of pathogen.: Viruses, bacteria, fungi and protists.
Cholera: pathogen type and effect?: Bacterium; causes diarrhoea.
Tuberculosis: pathogen type and effect?: Bacterium; causes lung damage.
Chalara ash dieback: pathogen type and effect?: Fungus; causes leaf loss and bark lesions in ash trees.
Malaria: pathogen type and effect?: Protist; causes damage to the blood and liver.
HIV: pathogen type and effect?: Virus; destroys white blood cells, leading to the onset of AIDS.
Stomach ulcers: which pathogen causes them? Triple only: Helicobacter, a bacterium.
Ebola: pathogen type and effect? Triple only: Virus; causes haemorrhagic fever.
How is cholera spread and how can this be reduced?: In contaminated water. Reduce by clean drinking water and sewage treatment.
How is tuberculosis spread and how can this be reduced?: Airborne, in droplets from coughs and sneezes. Reduce by isolating infected people and covering the mouth when coughing.
How is Chalara ash dieback spread and how can this be reduced?: Airborne spores. Reduce by destroying infected trees and restricting movement or import of ash plants.
What is a vector? Name the vector for malaria.: An organism that carries a pathogen from one host to another. The mosquito is the malaria vector.
How are stomach ulcers (Helicobacter) spread and how can this be reduced? Triple only: By oral transmission, for example swallowing bacteria in food or water. Reduce by good hygiene.
How is Ebola spread and how can this be reduced? Triple only: By contact with body fluids. Reduce by isolating patients and wearing protective clothing.
Describe the lytic pathway of a virus. Triple only: Viral genetic material takes over the host cell, new viruses are made, the cell bursts and releases them.
Describe the lysogenic pathway of a virus. Triple only: Viral genetic material joins the host DNA and stays dormant, copied when the cell divides, until it is triggered to become active.
How is chlamydia spread and how can this be reduced?: Unprotected sexual contact. Use condoms, screen and test, and treat with antibiotics.
How is HIV spread and how can this be reduced?: Sexual contact, sharing needles, infected blood, mother to baby. Use condoms, do not share needles, screen blood.

Plant defences and plant disease

How does the leaf cuticle protect a plant? Triple only: It is a waxy layer that forms a physical barrier, stopping pathogens and pests getting in.
How does the cell wall protect a plant? Triple only: It is a strong physical barrier around each cell that pathogens must get past.
How do chemicals help to defend plants? Triple only: Some kill or slow the growth of microorganisms, and some are poisons that deter pests.
How can plant chemicals be used by humans? Triple only: Some are used to treat disease or relieve symptoms. For example, aspirin was developed from a chemical in willow bark.
Why eliminate environmental causes when diagnosing a plant disease? Triple onlyHigher tier: To check that the symptoms are not caused by something like a mineral deficiency or drought rather than a pathogen.
What is distribution analysis for plant disease? Triple onlyHigher tier: Recording where affected plants are, to see whether the pattern suggests a spreading pathogen or a local environmental cause.
What are the two other ways of detecting and identifying plant disease? Triple onlyHigher tier: Observing visible symptoms, and diagnostic testing to identify the pathogen.

Human defences and immunity

How do mucus and cilia protect the airways?: Mucus traps pathogens; cilia move the mucus away from the lungs.
How does the skin protect against pathogens?: It is a physical barrier that pathogens cannot easily pass through.
What are lysozymes?: Enzymes that break down bacterial cell walls. A chemical defence.
What does hydrochloric acid in the stomach do?: It kills pathogens that are swallowed. A chemical defence.
What is an antigen?: A molecule, usually on the surface of a pathogen, that triggers an immune response.
What are antibodies?: Proteins made by white blood cells that bind to specific antigens and help to destroy the pathogen.
What are memory lymphocytes?: White blood cells made after exposure to an antigen that stay in the body and respond quickly if the antigen returns.
Describe the secondary immune response.: Memory lymphocytes recognise the antigen. The response is faster and produces more antibodies.
How does immunisation protect against a disease?: An inactive pathogen triggers antibody and memory lymphocyte production, so a later infection gets a fast secondary response.
Why does an inactive pathogen in a vaccine not make you ill?: It is dead or weakened, so it cannot cause the disease, but its antigens still trigger an immune response.
What is herd immunity? Triple only: When a large proportion of the population is immune, so the pathogen spreads poorly and non-immune people are protected.
Give two advantages of immunisation. Triple only: Protects the individual and reduces the spread of disease; also protects others through herd immunity.
Give two disadvantages of immunisation. Triple only: Side effects can occur; it does not always work or may need boosters.

Antibiotics, culturing microorganisms and new medicines

Why can antibiotics only treat bacterial infections?: They inhibit cell processes in the bacterium but not in the host. Viruses live inside host cells.
What is an autoclave used for? Triple only: Sterilising growth medium and petri dishes using high-pressure steam.
How is an inoculating loop made sterile? Triple only: Heated in a flame until red hot, then cooled before use.
Why keep petri dishes and culture vials covered? Triple only: To stop unwanted microorganisms getting in and the culture escaping.
Core practical: what does a clear zone show? Triple only: The substance (antiseptic, antibiotic or plant extract) killed bacteria or stopped them growing. A bigger zone means more effective.
Core practical: why use a control disc soaked in sterile water? Triple only: To show that the disc or water alone does not stop bacterial growth.
Equation for the cross-sectional area of a clear zone? Triple only: area = πr², where r is half the diameter.
Name the stages in developing a new medicine in order.: Discovery, development, preclinical testing, clinical testing.
What happens in preclinical and clinical testing?: Preclinical: tested on cells, tissues and live animals. Clinical: tested on people, first for safety and then for effectiveness.
What are monoclonal antibodies? Triple onlyHigher tier: Identical antibodies made from one type of cell that bind to one specific antigen.
How are hybridoma cells made? Triple onlyHigher tier: A lymphocyte that makes the desired antibody (but does not divide) is fused with a tumour cell.
Why are hybridoma cells useful? Triple onlyHigher tier: They divide to form many cells and they produce the antibody as they divide.
Give three uses of monoclonal antibodies. Triple onlyHigher tier: Pregnancy testing; diagnosis, including locating blood clots and cancer cells; treating diseases including cancer.
Advantage of monoclonal antibodies over drugs and radiotherapy for cancer? Triple onlyHigher tier: They target specific cells, so fewer healthy cells are damaged.

Non-communicable diseases

What causes many non-communicable diseases?: The interaction of a number of factors, such as lifestyle, environmental and inherited factors.
What is the BMI equation?: BMI = mass (kg) ÷ height (m)²
What does a high waist : hip ratio show?: More fat stored around the waist, linked to a higher risk of cardiovascular disease.
How do you calculate waist : hip ratio?: Waist circumference ÷ hip circumference, both in the same unit. The ratio has no units.
What are obesity and malnutrition?: Obesity is having too much body fat. Malnutrition is a diet without the right balance of nutrients.
How does drinking too much alcohol affect health?: It damages the liver, causing liver disease such as cirrhosis.
How does smoking affect cardiovascular health?: It damages artery linings, leading to fatty build-up and narrowing, and raises heart rate and blood pressure.
What are the three levels at which lifestyle effects are considered?: Local, national and global.
Name three types of treatment for cardiovascular disease.: Life-long medication, surgical procedures and lifestyle changes.
Give a disadvantage of each treatment for cardiovascular disease.: Medication: taken for life with side effects. Surgery: risks and recovery. Lifestyle changes: slow and need effort.