GCSE Biology unit 1.1

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DIET AND EXERCISE

7 food groups:

fibre- keeps the bowels working properly

water- used for chemical reactions and transport

protiens- used by the body to release energy and to build cells

carbohydrates- used by the body to release energy and to build cells

fat -used by the body to release energy and to build cells

minerals- needed in small amounts for healthy functioning of the body

vitamins- needed in small amounts for healthy functioning of the body

When food is digested, its components break down:

CARBOHYDRATES turn to GLUCOSE

FAT turns to FATTY ACIDS AND GLYCEROL

PROTIEN turns to AMINO ACIDS

Malnourished = unbalanced diet or when you lack something. Leads to deficiency diseases

Undernourished = eating too little (underweight)

Exercise

You lose weight if the amount of energy you take in is less than the amount of energy expendad by the body.

You gain weight if the amount of energy you take in is more than the amount of energy expendad by the body.

Metabolic rate= the rate at which all chemical reactions take place in the calls of your body

This is affected by:

proportion of muscle to fat

Amount of activity you do

Inherited factors

Obesity

You need some body fat to:

cushion internal organs

act as an energy source

Starvation

Muscles break down and waste away

Immune system doesnt work properly

Females periods stop

Cholesterol

Cholesterol is a lipid (fat).

It is found in cell membranes of animal cells as well as being involved in the formation of hormones and bile salts.

Cholesterol needs to be balanced

Cholesterol is made in the liver from saturated although sometimes it can be absorbed by high cholesterol foods.

There are two types of cholesterol:

healthy cholesterol

unhealthy (bad) cholesterol

If the balance isnt right your risk of getting heart disease increases.

The way your liver balances fat and makes different cholesterol is inherited. however you can eat a balanced diet and take statins to keep cholesterol level.

PATHOGENS AND DISEASE

Micro-organisms that cause infectious diseases are called pathogens.

When bacteria or viruses enter the body they reproduce rapidly making you feel ill by producing toxins.

Viruses are smaller than bacteria but reproduce inside cells also making you feel ill.

Washing hands removes pathogens semmelweiss was the first to discover this.

Doctors and other medical professions use semmelweiss' results today in hospitals by washing equipment and hands when dealing with patients.

The body has many defence mechanisms such as the white blood cells that fight diseases:

they ingest pathogens

they produce antibodies that lock onto pathogens antigens and kills them

they produce antitoxins to counteract toxins produced by pathogens

Penicillin was discovered by Alexander Fleming and developed by Florey and Chain, saving many lives in the second world war.

Antibiotic resistant bacteria evolve through natural selection

vaccines prevent against infection. dead or inactive forms of a pathogen are injected into the body tricking the white blood cells into producing specific antibodies to fight off the pathogen. the cell then remembers these antibodies so when the pathogen attacks it can kill it much quicker.