Edexcel GCSE Biology (1BI0) — Health, Disease and Medicines
Every time you drink a glass of tap water, you trust that it is free from microscopic threats. However, in areas with poor sanitation, water can carry a dangerous pathogen that causes severe illness.
The Mechanism of Cholera (Step-by-Step):
A simple cough on a crowded bus can launch thousands of tiny, invisible droplets into the air, creating a pathway for respiratory diseases to spread.
The Effect of TB on the Body:
Calculate the percentage increase in tuberculosis cases if a local clinic reports a rise from 450 cases to 630 cases over one year.
Step 1: Identify the old and new values.
Step 2: State the formula and substitute the values.
Step 3: Calculate the difference in the numerator.
Step 4: Divide and multiply by 100 to find the final percentage.
The human stomach is an incredibly hostile environment full of strong acid, yet some specialised microbes have evolved to thrive right there.
How Stomach Ulcers Form (Step-by-Step):
Students often confuse the modes of transmission for these diseases; remember that cholera is waterborne, whereas tuberculosis is airborne.
For 3-mark 'Describe' questions on stomach ulcers, examiners expect a specific sequence: state that the bacteria damage the mucus lining, explain that this allows hydrochloric acid to reach the stomach wall, and conclude that this causes the ulcer.
When explaining cholera for higher tier questions, you must link the symptom of diarrhoea directly to the movement of water by osmosis due to the secretion of chloride ions.
Always identify the causative agents of these three diseases specifically as 'bacteria' rather than using vague terms like 'germs' or 'microbes'.
Pathogen
A microorganism, such as a bacterium or virus, that causes disease.
Bacterial
Relating to or caused by bacteria, which are single-celled microorganisms that can cause communicable diseases.
Vibrio cholerae
The specific pathogenic bacterium that causes the waterborne disease cholera.
Waterborne transmission
A method of disease spread where pathogens are carried in water and enter the host through drinking or washing.
Contaminated water
Water that contains harmful pathogens, often due to mixing with untreated human faeces.
Chloride ions
Charged particles that are pumped into the gut by cells infected with cholera, lowering the water potential.
Water potential
A measure of the tendency of water molecules to move from one place to another; water moves from a high to a low water potential.
Osmosis
The movement of water molecules from a region of higher water potential to a region of lower water potential across a partially permeable membrane.
Diarrhoea
The frequent passing of severe, watery faeces, which is the primary symptom of cholera.
Dehydration
A rapid and dangerous loss of water and essential salts from the blood and body tissues.
Communicable disease
A disease caused by a pathogen that can be spread from one organism to another.
Mycobacterium tuberculosis
The pathogenic bacterium responsible for causing tuberculosis (TB).
Airborne transmission
The spread of a pathogen via small respiratory droplets that remain suspended in the air and are inhaled by others.
Respiratory system
The biological system involved in breathing and gas exchange, primarily targeted by the tuberculosis bacterium.
Lung damage
The destruction of lung tissue caused by an infection like TB, leading to symptoms such as coughing up blood.
Helicobacter pylori
The acid-tolerant bacterium that infects the stomach lining and causes most stomach ulcers.
Oral transmission
The spread of a pathogen through the mouth, typically via contaminated food, water, or shared utensils.
Urease
An enzyme produced by Helicobacter pylori that neutralises stomach acid, allowing the bacterium to survive.
Mucus lining
A thick protective layer secreted by the stomach wall that prevents the tissue from being digested by its own acid.
Hydrochloric acid
The strong acid found in the stomach that aids digestion but causes tissue damage if the mucus lining is breached.
Epithelial cells
The cells that make up the inner lining of the stomach wall, which become damaged during ulcer formation.
Stomach ulcer
An open sore or lesion in the lining of the stomach caused by the breakdown of the protective mucus layer.
Put your knowledge into practice — try past paper questions for Biology
Pathogen
A microorganism, such as a bacterium or virus, that causes disease.
Bacterial
Relating to or caused by bacteria, which are single-celled microorganisms that can cause communicable diseases.
Vibrio cholerae
The specific pathogenic bacterium that causes the waterborne disease cholera.
Waterborne transmission
A method of disease spread where pathogens are carried in water and enter the host through drinking or washing.
Contaminated water
Water that contains harmful pathogens, often due to mixing with untreated human faeces.
Chloride ions
Charged particles that are pumped into the gut by cells infected with cholera, lowering the water potential.
Water potential
A measure of the tendency of water molecules to move from one place to another; water moves from a high to a low water potential.
Osmosis
The movement of water molecules from a region of higher water potential to a region of lower water potential across a partially permeable membrane.
Diarrhoea
The frequent passing of severe, watery faeces, which is the primary symptom of cholera.
Dehydration
A rapid and dangerous loss of water and essential salts from the blood and body tissues.
Communicable disease
A disease caused by a pathogen that can be spread from one organism to another.
Mycobacterium tuberculosis
The pathogenic bacterium responsible for causing tuberculosis (TB).
Airborne transmission
The spread of a pathogen via small respiratory droplets that remain suspended in the air and are inhaled by others.
Respiratory system
The biological system involved in breathing and gas exchange, primarily targeted by the tuberculosis bacterium.
Lung damage
The destruction of lung tissue caused by an infection like TB, leading to symptoms such as coughing up blood.
Helicobacter pylori
The acid-tolerant bacterium that infects the stomach lining and causes most stomach ulcers.
Oral transmission
The spread of a pathogen through the mouth, typically via contaminated food, water, or shared utensils.
Urease
An enzyme produced by Helicobacter pylori that neutralises stomach acid, allowing the bacterium to survive.
Mucus lining
A thick protective layer secreted by the stomach wall that prevents the tissue from being digested by its own acid.
Hydrochloric acid
The strong acid found in the stomach that aids digestion but causes tissue damage if the mucus lining is breached.
Epithelial cells
The cells that make up the inner lining of the stomach wall, which become damaged during ulcer formation.
Stomach ulcer
An open sore or lesion in the lining of the stomach caused by the breakdown of the protective mucus layer.
