Biology Revision B1.1

Healthy Diets:

• to maintain a healthy diet, you need to eat the correct balance of carbohydrates, fats, proteins, fibre, vitamins, minerals, water and energy
• carbohydrates, proteins and fats allow the body to release energy and build cells
• minerals and vitamins are needed in small amounts for a healthy functioning body
• if their diet is not balanced, a person may become malnourished, and this can lead to
• them becoming underweight or overweight
• deficiency diseases, eg. scurvy or type 2 diabetes

Exercise:

• exercise increases the amount of energy expended by the body
• mass is lost if the energy expended through exercise is more than the energy consumed

Metabolic Rate:

• the metabolic rate is the rate at which all the chemical reactions in the cells of the body are carried out
• this varies with the amount of exercise you do, and the proportion of fat to muscle

Bacteria and Viruses:

• microorganisms that cause infectious diseases are called pathogens
• there are two types of pathogens
• bacteria, which are very small, reproduce very quickly, can produce toxins that make us ill, and cause tetanus, cholera an tuberculosis
• viruses, which are even smaller, reproduce very quickly once inside living cells ( which are then damaged ), can produce toxins that make us I'll, and cause colds, flu and measles

Defence against Pathogens:

• white blood cells form part of the body's immune system, and fight infection by
• ingesting pathogens
• producing antitoxins
• producing antibodies

Treatment of Disease:

• although painkillers are useful, they don't kill pathogens

Antibiotics:

• antibiotics ( such as penicillin ) are often used to kill bacteria inside the body
• specific antibiotics = specific bacteria
• cannot kill viruses
• difficult to develop drugs that destroy viruses without damaging the body's tissues

Overuse of Antibiotics:

• overuse can lead to resistance
• resistance happens when bacteria mutate to produce a new resistant strain

Vaccination:

• a person can squire immunity through vaccination, this is the process
• inactive/ dead pathogen infected into body
• white blood cells produce antibodies to destroy pathogen
• immune
• used for measles, mumps, rubella etc.

Preparing a Culture Medium
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