B2: Keeping Healthy

"What are pathogens?"

"Pathogens are agents, usually live microorganisms such as bacteria, viruses, fungi, or protists, that cause infectious disease."

"How do pathogens harm the body?"

"Pathogens destroy cells, produce toxins, and inhibit cells from carrying out their usual functions, which reduces mental and physical health."

"What is an incubation period?"

"The incubation period is the time after infection before symptoms appear, during which the pathogen replicates inside the body."

"What is the difference between communicable and non-communicable diseases?"

"Communicable diseases are infectious and can be spread between organisms, while non-communicable diseases are usually caused by genetic, environmental, or lifestyle factors and cannot be directly transmitted."

"Give examples of communicable human diseases and their pathogens."

"Influenza - Influenza virus, Salmonella - Salmonella bacteria, Athlete's foot - fungi (Trichophyton, Epidermophyton, Microsporum), Malaria - Plasmodium protist, HIV - Human Immunodeficiency Virus."

"How are communicable diseases transmitted?"

"Through direct contact, airborne microorganisms, indirect contact (infected surfaces), or contaminated food and water."

"What is a vector?"

"A vector is an organism that carries a disease without being infected itself, e.g., a mosquito transmitting malaria."

"What are the body's non-specific defences against pathogens?"

"Mechanical barriers (hairs, skin), chemical barriers (mucus, stomach acid, tears), and bacterial barriers (friendly gut bacteria)."

"What is the role of platelets?"

"Platelets are cell fragments that promote blood clotting, forming a mesh at cuts to stop bleeding and prevent pathogen entry."

"How do white blood cells defend the body?"

"They detect pathogens using receptors, then engulf and digest them or release chemicals to trigger antibody production and label pathogens for destruction."

"What are antibodies?"

"Y-shaped proteins that bind to specific antigens on pathogens, neutralising them and causing agglutination for easier destruction by white blood cells."

"What are memory cells?"

"Memory cells are long-lived white blood cells that remember a pathogen and allow the body to respond faster if it is encountered again."

"What are plant defences against pathogens?"

"Physical barriers (cell wall, waxy cuticle) and antimicrobial substances, some of which are produced in response to infection."

"How can the spread of plant disease be prevented?"

"Regulate movement of plants, source healthy seeds, destroy infected plants, use polyculture, rotate crops, and apply chemical or biological controls."

"How can human and animal disease be prevented?"

"Contraception, sterilising wounds, hygiene and sanitation, restricting travel, destroying infected animals, and vaccination."

"What is herd immunity?"

"When enough people are immune to a disease, its spread is reduced, protecting those who cannot be vaccinated."

"Why must the costs

benefits, risks, and ethics be considered in disease prevention?","Because some methods, like vaccination, affect individual choice, risk, and societal health."

"How can diseases be identified?"

"By observing symptoms, cell counting, culture, microscopy and staining, antimicrobial testing, and genome analysis."

"What are aseptic techniques?"

"Procedures used to prevent contamination of samples and stop the spread of pathogens, e.g., sterilising equipment, cleaning surfaces, washing hands."

"What are monoclonal antibodies?"

"Identical antibody clones made from one parent cell, used in diagnostic tests and treatments by binding specifically to target molecules."

"How are monoclonal antibodies produced?"

"Inject antigen into an animal → extract antibody-producing cells → fuse with tumour cells to make hybridomas → select and culture cells producing the correct antibody."

"What are risk factors for non-communicable diseases?"

"Unhealthy diet, lack of exercise, age, inherited genes, environmental factors, drugs, and smoking."

"Give examples of interactions between diseases."

"Autoimmune diseases weaken immunity; HIV increases risk of other infections; sickle cell anaemia prevents malaria; some viruses trigger cancer."

"How do medicines treat disease?"

"By curing the disease, reducing symptoms, or decreasing illness duration."

"How do antibiotics work?"

"Antibiotics kill or inhibit bacterial growth, e.g., destroying cell walls or inhibiting reproduction. They do not work on viruses."

"How does bacterial resistance develop?"

"Mutations create resistant bacteria which survive antibiotic treatment, reproduce, and increase the population of resistant strains."

"How can the development of antibiotic resistance be slowed?"

"Use antibiotics only for serious infections and complete the full course."

"What are treatments for cardiovascular disease?"

"Lifestyle changes, drugs (statins, blood pressure medications), stents, or heart transplants, depending on severity and patient factors."

"What are the stages of new drug development?"

"1) Screening of substances 2) Pre-clinical trials (computer, tissue, animal) 3) Clinical trials (healthy humans, patients, placebo, blind/double-blind tests)."

"What are monoclonal antibodies used for in cancer treatment?"

"They target specific antigens on cancer cells, label them for destruction, or carry toxic/radioactive substances to kill the cancer cells."