1.1 – Discuss the difficulties of defining the terms ‘health’ and ‘disease’:
Health:
 Defined as the wellbeing of the organism.
 i.e. the physical, mental and social states of the individual.
 Difficulties: o Different people have different levels of ‘wellbeing; when they say they are healthy. o E.g. a fit person will say they are healthy if they currently do not have a disease. o However, a person with a chronic disease will say they are healthy if the symptoms are not too bad that day. o Difficult to define as health has many components, such as physical, mental, and social, some of which are very subjective.
Disease:
 Defined as any condition that adversely affects the function of any part of a living thing.
 E.g. a scrape on the knee to a serious organ malfunction and cancers.
 Difficulties: o There can be confusion between disabilities and disease, e.g. health reports will state arthritis is a disabling condition rather than a disease. o Have many components. Because it is describing a state of impaired functioning, it depends on an organism’s normal level of functioning, and what they expect their quality of life to be.
1.2 – Outline how the function of genes, mitosis, cell differentiation and specialisation in the maintenance of health:
Genes:
 Genes control the production of proteins in the body (needed for proper functioning) and so healthy genes ensure the correct proteins are made.
 Through production of proteins (especially enzymes), genes ensure the correct cell processes occur, maintaining metabolism and homeostasis.
Mitosis:
 Mitosis is the process that enables genetic material to be copied exactly, ensuring the genes are correct and able to maintain health in their own way
 Mitosis is also the process that organisms use to grow, and maintain and repair body cells, maintaining health
Cell Differentiation and Specialisation:
 These 2 processes result in cells which are specialised for specific functions in the body, such as red blood cells, etc.
 Together, all the specialised body cells work together in a coordinated way to maintain the health and proper functioning of the organism.
1.3 – Use available evidence to analyse the links between gene expression and maintenance and repair of body tissues:
 Gene expression occurs when a gene is ‘switched on’ and the DNA code is converted into polypeptides that control the structures and functions of a cell.
 If the DNA is damaged gene expression will cause the production of a variety of enzymes that can repair damaged DNA, e.g. some repair enzymes can cut out the damages DNA and make new DNA to replace it.
 There are also enzymes that prevent copying errors when DNA is replicated – this is called
‘proofreading’.
 Gene expression can lead to the replacement of some cells, e.g. lining the intestines, as these calls are too damaged by the digestion process to be repaired.
 If a cell is exposed to very high temperatures it can switch on a gene to make ‘heat shock proteins’. These heat shock proteins can be produced very rapidly and can stabilise the other proteins in the cell. This helps protect the cell allowing it to function for longer.

2.1 – Distinguish between infectious and non-infectious disease:
 Infectious disease: a disease caused by an organism and can be transferred from one person to another. o caused by an invasion of the body by pathogens (an infectious agent that causes disease). o E.g. viruses (influenza), bacteria (tonsillitis), protozoans (malaria), prions (CJD), fungi
(tinea).
 Non-infectious disease: not caused by a disease-causing organism and apart from genetic diseases from parent to child, cannot be transferred from one person to another. o Involves no pathogens o No transfer of the disease form one person to another. o E.g.:
 Inherited (genetic) disease: Down’s Syndrome, haemophilia
 Nutritional disease: scurvy, beriberi, kwashiorkor
 Environmental disease: skin cancer, asbestosis
2.2 – Explain why cleanliness in food,