baseline year 11

define the term health

health is a state of complete physical, mental and social well-being, not just the absence of disease

define the term disease

disease is a condition that impairs the normal functioning of an organism

describe how communicable and non-communicable diseases differ

communicable diseases are caused by pathogens and can be spread between individuals, whereas non-communicable diseases are not caused by pathogens and cannot be passed from person to person

outline the role of the immune system in protecting against disease

the immune system detects pathogens using antigens and responds by producing white blood cells. phagocytes ingest and destroy pathogens, while lymphocytes produce antibodies that bind to antigens and memory cells that give long-term immunity

explain how disease can affect the immune system

some diseases damage or weaken the immune system, reducing its ability to respond to pathogens, this makes the body more vulnerable to infections and can cause existing diseases to become more severe

give examples of non-communicable diseases

examples include coronary heart disease, type 2 diabetes, cancers, and cirrhosis of the liver

define the term malnutrition

malnutrition is a condition that occurs when the diet does not provide the right balance of nutrients, which may be too much or too little

explain how diet can lead to malnutrition

an unbalanced diet can cause deficiencies (e.g. lack of vitamin d causing rickets, or lack of iron causing anaemia) or excess intake (e.g. too much fat leading to obesity). therefore both undernutrition and overnutrition can cause malnutrition

describe the link between alcohol and liver disease

alcohol is broken down by the liver, producing toxic by-products. heavy or long-term drinking damages liver cells, leading to scarring (cirrhosis), impaired function, and eventually liver failure

explain the effect of alcohol consumption on liver disease at local level

individuals may suffer health problems, reduced ability to work, and family/social impacts

explain the effect of alcohol consumption on liver disease at national level

healthcare systems face increased costs for treating alcohol-related disease, and productivity decreases

explain the effect of alcohol consumption on liver disease at global level

widespread alcohol misuse contributes to millions of deaths annually, placing strain on global health services and economies

describe how obesity is measured (bmi)

obesity can be measured using body mass index (bmi), calculated as body mass ÷ height². a bmi over 30 is classed as obese

describe how obesity is measured (waist:hip calculations)

waist:hip ratio is another method, calculated by dividing waist circumference by hip circumference; higher ratios show more abdominal fat and a greater health risk

describe how obesity correlates with cardiovascular disease

obesity increases blood pressure and cholesterol levels, which raises the risk of atherosclerosis (fatty deposits in arteries) and cardiovascular diseases such as heart attack and stroke

describe how smoking correlates with cardiovascular disease

chemicals in tobacco damage the lining of arteries, increasing the risk of atherosclerosis. nicotine raises heart rate and blood pressure, while carbon monoxide reduces oxygen transport, all of which increase the risk of cardiovascular disease

explain why exercise and diet affect obesity

exercise increases energy expenditure, reducing excess fat storage. a balanced diet prevents excess intake of energy and fat. lack of exercise and a high-energy diet together increase the risk of obesity

compare how cardiovascular diseases are treated (lifestyle changes)

healthy diet, exercise, stopping smoking reduce risk factors

compare how cardiovascular diseases are treated (medication)

statins lower cholesterol, anticoagulants reduce clotting, antihypertensives lower blood pressure

compare how cardiovascular diseases are treated (surgery)

stents keep arteries open, bypass surgery replaces blocked arteries, and heart transplants may be used in severe cases

describe some problems and diseases caused by bacteria

bacteria can release toxins or directly damage host cells. examples include cholera (causing diarrhoea and dehydration), tuberculosis (damaging the lungs), and food poisoning (causing vomiting and diarrhoea)

describe a disease caused by a virus

ebola is a viral disease that damages cells and tissues, causing fever, internal bleeding and a high fatality rate

describe a disease caused by a protist

malaria is caused by the protist plasmodium, spread by female anopheles mosquitoes. it infects red blood cells and liver cells, causing fever, chills and potentially death

describe a disease caused by a fungus

chalara ash dieback is a fungal disease of ash trees, causing leaf loss, bark lesions and dieback of branches, leading to death of the tree

explain how signs of a disease can be used to identify the pathogen

different pathogens produce distinct symptoms. for example, diarrhoea may suggest cholera, bleeding indicates ebola, and a skin rash may suggest fungal infection. patterns of symptoms can be matched to specific diseases to help identify the pathogen

state the ways in which pathogens can be spread

pathogens can be spread by air (droplets), water, food, vectors, direct contact, contaminated surfaces, and body fluids

give examples of pathogens that are spread in different ways (water)

cholera bacteria spread in contaminated water

give examples of pathogens that are spread in different ways (air)

tuberculosis bacteria and chalara ash dieback fungus spread in air

give examples of pathogens that are spread in different ways (vector)

malaria protist spread by female anopheles mosquitoes

give examples of pathogens that are spread in different ways (mouth)

helicobacter bacteria spread by contaminated food or saliva

give examples of pathogens that are spread in different ways (body fluids)

ebola virus spread through blood and other bodily fluids

explain how the spread of different pathogens can be reduced or prevented (water)

improve sanitation, clean water supply

explain how the spread of different pathogens can be reduced or prevented (air)

isolate infected individuals, good ventilation, removing/destroying infected plants

explain how the spread of different pathogens can be reduced or prevented (vector)

use mosquito nets, insect repellent, and insecticide spraying

explain how the spread of different pathogens can be reduced or prevented (oral)

good food hygiene, washing hands

explain how the spread of different pathogens can be reduced or prevented (body fluid)

protective clothing, sterilising equipment, isolating infected people

describe the structure of a virus

a virus consists of genetic material (dna or rna) surrounded by a protein coat called a capsid. some viruses also have an envelope derived from host cell membrane

explain how viruses differ from cells

viruses are not cells: they lack cytoplasm, organelles and a cell membrane. they cannot carry out metabolism or reproduce on their own, and must infect host cells to replicate

describe the lytic pathway of a virus life cycle

the virus attaches to a host cell, injects its genetic material, and uses the host’s machinery to make viral proteins and nucleic acids. new virus particles are assembled, then the host cell bursts (lysis), releasing viruses to infect more cells

describe the lysogenic pathway of a virus life cycle

the viral dna is inserted into the host cell’s genome and is replicated each time the cell divides. the virus remains dormant until triggered, at which point it switches to the lytic pathway

compare and contrast the lytic and lysogenic pathways (similarities)

both involve viral dna entering a host cell

compare and contrast the lytic and lysogenic pathways (differences)

in the lytic pathway, the virus immediately replicates and destroys the host cell. in the lysogenic pathway, the viral dna integrates into the host genome and remains dormant until activated

calculate the cross-sectional area of viral cultures and clear agar jelly

measure the radius of the clear zone, apply the formula area = πr², compare areas to estimate viral effect on bacterial growth

describe some physical barriers of plants to pests and pathogens

plants have a waxy cuticle on leaves that prevents pathogen entry, cell walls that provide structural protection, and layers of dead cells such as bark that act as a barrier

describe some chemical defences of plants to pests and pathogens

plants produce antibacterial chemicals, antifungal chemicals, and toxins that deter insect pests

describe how plant protective chemicals are used to treat human diseases or symptoms

plant chemicals are sources of medicines: aspirin (from willow bark) is used as a painkiller, and quinine (from cinchona bark) is used to treat malaria

describe examples of aseptic technique

examples include sterilising equipment with heat or alcohol, flaming the neck of bottles before use, disinfecting surfaces, working near a bunsen burner to create an updraft, and minimising time lids are off agar plates

explain why aseptic technique is used during the culture of microorganisms

aseptic technique prevents contamination of cultures with unwanted microorganisms, ensuring reliable results and protecting people from potential pathogens

describe how plant diseases are detected using visible symptoms

plant diseases can be identified by symptoms such as leaf discolouration, lesions, spots, abnormal growths, wilting, or dieback. these visible signs suggest infection by pathogens

describe how environmental causes of plant problems are eliminated when identifying disease

to confirm disease, other factors such as nutrient deficiencies, drought, poor soil, or pollution must first be ruled out, since these can cause similar symptoms without infection

describe how distribution analysis can help identify a plant disease

studying the pattern of affected plants can indicate whether symptoms are due to disease. for example, random distribution suggests an infectious pathogen, while widespread or uniform patterns may suggest environmental factors like nutrient deficiency

describe how plant pathogens are diagnosed in the lab

diagnosis can involve microscope examination, culturing pathogens, testing plant sap for specific antigens using monoclonal antibodies, and identifying pathogen dna using pcr

explain how the spread of chlamydia can be reduced or prevented

use of condoms, screening, and treatment with antibiotics reduce spread

explain how the spread of HIV can be reduced or prevented

use of condoms, not sharing needles, blood screening, and antiretroviral drugs reduce transmission

give examples of physical barriers

skin, mucus, cilia, and scabs

give examples of chemical barriers

lysozymes in tears and saliva, hydrochloric acid in the stomach, and antimicrobial secretions on the skin

describe how physical barriers protect the body (e.g. skin, mucus and cilia)

the skin forms a tough barrier to pathogens; mucus traps microorganisms in the airways; cilia move mucus up the throat where it can be swallowed and destroyed

describe how chemical barriers protect the body (e.g. lysozymes, hydrochloric acid)

lysozymes are enzymes that break down bacterial cell walls, killing bacteria; hydrochloric acid in the stomach destroys many pathogens in food or mucus

state that the immune system protects the body by attacking pathogens

the immune system protects the body by recognising, attacking, and destroying pathogens

describe how antigens trigger the release of antibodies and the production of memory lymphocytes

pathogens have antigens on their surface. lymphocytes detect these antigens and produce specific antibodies that bind to them. some lymphocytes become memory cells, remaining in the blood to give long-term immunity

describe the role of antibodies in the immune response

antibodies bind to antigens on pathogens, neutralising them, clumping them together, and marking them for destruction by phagocytes

describe the role of memory lymphocytes in triggering a secondary response

memory lymphocytes remain in the body after infection. if the same pathogen enters again, they produce large amounts of antibodies rapidly, giving a faster and stronger secondary response

explain how immunisation protects against infection by a pathogen

a vaccine containing dead or inactive pathogens is introduced. the antigens stimulate the immune system to produce antibodies and memory lymphocytes. this means the body can respond quickly if exposed to the real pathogen

discuss advantages of immunisation including herd immunity

protects individuals from serious disease, prevents spread, can lead to herd immunity where unvaccinated people are protected because the pathogen cannot spread easily

discuss disadvantages of immunisation including herd immunity

some people may have mild side effects, vaccines may not give lifelong immunity, and not all pathogens have effective vaccines

define the term antibiotic

antibiotics are chemical medicines that kill bacteria or inhibit their growth by interfering with bacterial cell processes such as cell wall formation, protein synthesis, or DNA replication

explain why antibiotics are useful for treating bacterial infections

antibiotics target processes specific to bacterial cells, which are different from human cells, so they can kill or inhibit bacteria without harming human cells

explain why antibiotics cannot be used to treat infections by pathogens other than bacteria

viruses lack metabolic processes and do not have cell structures like bacteria, so antibiotics cannot disrupt them. similarly, fungi and protists have different cell biology, so antibiotics are ineffective

describe the stages of development of new medicines (preclinical testing)

testing on cells, tissues, and animals to check for safety, toxicity, and effectiveness, identifies any major toxicity and ensures potential effectiveness before human exposure

describe the stages of development of new medicines (clinical trials)

testing in humans: phase 1 tests safety in a small group, phase 2 tests dosage and effectiveness, phase 3 tests large-scale effectiveness and monitors side effects, confirm safety and effectiveness in humans, determine the optimal dose, and reveal common side effects

describe the stages of development of new medicines (licensing and monitoring)

regulatory authorities approve safe and effective medicines, and post-marketing surveillance continues to detect rare or long-term side effects, ensures only safe medicines reach the public and rare side effects are detected after widespread use

define the term monoclonal antibody

a monoclonal antibody is a laboratory-produced antibody that is specific to a single type of antigen

define the term hybridoma cell

a hybridoma cell is created by fusing an antibody-producing lymphocyte with a tumour cell, producing a cell that can divide indefinitely and produce monoclonal antibodies

describe how monoclonal antibodies are produced by lymphocytes

lymphocytes that produce a specific antibody are fused with tumour cells to form hybridoma cells. these hybridomas divide repeatedly to produce large quantities of identical monoclonal antibodies

explain how monoclonal antibodies are used in pregnancy testing

monoclonal antibodies on a pregnancy test strip bind to the hormone hcg in urine. if hcg is present, it binds to the antibodies and produces a visible line or symbol, indicating pregnancy

explain how monoclonal antibodies are used in diagnosis of disease (including blood clots and cancer)

monoclonal antibodies can bind to specific disease markers, such as antigens on cancer cells or proteins in blood clots. they can be linked to dyes or radioactive markers to detect the presence and location of disease in the body

explain the advantages of monoclonal antibodies compared with drug and radiotherapy treatments to target cells

monoclonal antibodies specifically target diseased cells without affecting healthy cells, reducing side effects. this is more precise than some drugs or radiotherapy, which can damage healthy tissues