Health, Nutrition, and Human Diseases
This domain tests the components of a balanced diet, deficiency diseases, types of disease, and the body's defences against infection.
Core rules
- A balanced diet provides carbohydrates, proteins, fats, vitamins, minerals, fibre, and water in suitable amounts. Carbohydrates and fats are energy sources; proteins are needed for growth and repair.
- Deficiency diseases include scurvy from lack of vitamin C, night blindness from lack of vitamin A, rickets from lack of vitamin D or calcium, and anaemia from lack of iron.
- Communicable diseases spread from person to person or through vectors, food, water, or air. Non-communicable diseases such as diabetes and hypertension are not spread between people.
- Pathogens include bacteria, viruses, fungi, and protozoa. Vaccination exposes the body to weakened or inactive antigens so that memory cells can respond quickly later.
Worked example
A child has bleeding gums and slow wound healing. Which nutrient is likely deficient? Bleeding gums and poor wound healing are classic signs of vitamin C deficiency, called scurvy. Vitamin C is needed for collagen formation. The advice is to include citrus fruits, amla, and other vitamin C-rich foods. The reasoning links a specific symptom to a specific nutrient function, not to a general idea of poor diet.
Traps that cost marks
Do not say antibiotics cure viral infections such as influenza. Do not confuse a vector with a pathogen; a mosquito carries the malaria parasite but is not the parasite. Do not assume all vitamins are fat-soluble; vitamin C and B vitamins are water-soluble. Deficiency signs must be matched to the correct nutrient.
Key points
- A balanced diet supplies energy, growth materials, vitamins, minerals, fibre, and water.
- Scurvy is vitamin C deficiency; night blindness is vitamin A deficiency.
- Communicable diseases spread; non-communicable diseases do not.
- Vaccination builds immune memory.