Biology: the Search for Better Health

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THE SEARCH FOR BETTER HEALTH

1.What is a healthy organism?
Discuss the difficulties in defining the terms ‘health’ and ‘disease’ * Health – state of physical, mental and social wellbeing. It is not just absence of disease * disease – any condition which effects the functioning of any part of a living organism * difficulties in defining health and disease;

* health
1) the definition of health varies with age eg stiffness in the joints is probably more common in a 90yo than for a 20yo 2) it is possible for a person to have a disease but be healthy at the same time eg arthritis 3) health varies on a daily basis: some days we are full of energy and on others we feel lethargic * disease

4) the definition is very broad eg even minor ailments such as a cut finger using this definition would be regarded as a disease Functioning of genes, mitosis, differentiation and cell specialisation are important in the maintenance of health * Genes = the units of inheritance. A gene is a small section of a DNA molecule that controls the production of a polypeptide or protein. Genes control the cell cycle, production of enzymes and production of other proteins including structural proteins and hormones. If a particular gene is not functioning correctly, the correct protein will not be made and body function will be impaired * Mitosis = type of cell division that produces new body cells. Mitosis allows for growth, repair and maintenance. If the genes that regulate the process of mitosis are permanently switched on then cancer will result. * Cell differentiation = the process where cells produced by mitosis became sorted out to form a certain cell type. Cells produced by a cancer tumour do not differentiate * Cell specialisation = the body contains many different types of cells white, red blood, bone, skin – these specialised cells are produced by cell differentiation. There are unique body cells called stem cells that have the ability to form into any other type of blood cell Links between gene expression and the maintenance and repair of body tissue * gene expression occurs when genes are “switched on” – when a gene is being expressed it will cause a particular polypeptide or protein to be produced * polypeptides join to form

2.Over 3000 years ago the Chinese and Hebrews were advocating cleanliness in food, water and personal hygiene Distinguish between infectious and non-infectious disease
* An infectious disease is one that is caused by a living organism * Most living organisms that cause disease are micro-organisms. Not all organisms in the tissues of another organism cause disease. A disease causing organism is called a pathogen. The major groups of pathogens include; bacteria, viruses, fungi, protozoa, prions, macro-parasites eg tapeworms * EXAMPLES – influenza (virus), tuberculosis (bacteria) * A non-infectious disease is not causes by a pathogen i.e. it has some other cause, eg hearts disease (genetics, diet, smoking. Exercise, cancer) Explain why cleanliness in food, water, personal hygiene practices assist in the control of disease Food

* Food needs to be fresh
* Storing food under suitable conditions – refrigerating, freezing * Personal hygiene used by food handlers in food surface industries * Proper cooking of food to kill pathogens eg meat
Water
* To ensure that water catchment areas used for water storage are kept contamination free from things eg poop or dead cows * Water is treated by bubbling chlorine gas through it to kill pathogens in the water Hygiene practices

* Washing hands before handling food and avoid handling foods with bare hands * Community hygiene practices include; proper garbage disposal, proper sewage disposal and treatment, city planning to prevent overcrowding, sterilization of equipment used in medical procedures

Conditions under which organisms can be regarded as a pathogen

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