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 are passed from person to person, while non-communicable diseases cannot be.
2. Communicable diseases are caused by pathogens, such as bacteria or viruses, whereas non-communicable diseases are not caused by pathogens and do not spread among individuals.

One way to reduce the spread of tuberculosis is through vaccination, which helps provide immunity and reduces the chance of a person getting infected.

The completed table would include each country listed with the corresponding number of people with TB:

The human body has a variety of physical barriers and chemical defenses that protect against disease:

Physical Barriers

• Skin: Acts as a thick covering, preventing pathogens from entering. It is waterproof and has dead cells on its surface.
• Mucus: Secreted by cells lining the surfaces of the body, it traps pathogens.
• Cilia: Tiny hair-like structures that line the respiratory system, moving pathogens out of the body.
• Tears: Wash away pathogens from the eyes.
• Nasal hairs: Trap pathogens entering the respiratory system.

Chemical Defences

• Lysozymes: Enzymes found in tears and saliva that kill some bacteria.
• Hydrochloric Acid: Present in the stomach, it creates a low pH environment that kills many pathogens.
• Antibodies: Produced by the immune system to target and neutralize pathogens.