6. (a) Name the organisation which defines health as a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity - Edexcel - GCSE Biology Combined Science - Question 6 - 2021 - Paper 1

1. Communicable diseases can be passed from person to person, while non-communicable diseases cannot.

2. Communicable diseases are often caused by pathogens, whereas non-communicable diseases typically result from genetic factors or lifestyle choices.

One way to reduce the spread of tuberculosis (TB) is through vaccination. Vaccinating individuals can provide immunity and reduce the chances of getting infected by the bacteria that cause TB.

The human body employs various physical barriers and chemical defences to protect itself from diseases:

Physical Barriers

1. Skin - Acts as a thick, waterproof barrier that prevents pathogens from entering the body.
2. Mucus - Traps pathogens and helps wash them away through mechanisms like coughing or sneezing.
3. Cilia - Tiny hair-like structures that line the respiratory system, moving pathogens out of the airway.

Chemical Defences

1. Lysozymes - Enzymes present in tears and saliva that can kill certain bacteria.
2. Hydrochloric Acid - Found in the stomach, it creates an acidic environment that kills many pathogens that enter the digestive system.
3. Antibodies - Proteins that the immune system produces to specifically target and neutralize pathogens, providing targeted protection.