Biology Unit 1

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Diet and Energy

People should eat a balanced diet which contains carbs, fats and proteins for energy. Along with small amount of vitamins and mineral ions for keeping healthy.

If your diet is not balaced you may become malnourished (too fat or too thin)

Metabolic rate is the rate at which chemical reactions take place in your cells.

The greater the proportion of muscle to fat in the body, the higher the metabolic rate is likely to be.

Metabolic rate can be affected by your genes, which you inherit from your parents.

One gram of fat releases more energy than one gram of carbs.

Proteins are not usually a major source of energy.

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Diet, Exercise and Health

A high level of cholesterol increases the risk of developing plaques in the arteries.

Sometimes a clot blocks one of the arteries and takes oxygenated blood to the hearth muscles. This can cause a heart attack.

Eating saturated fats raises blood cholesterol.

Some people are better at having a lower blood cholesterol than others

Cholesterol is carreid in the blood in two ways:

Low-density lipoprotein (LDL)

High-density lipoprotein (HDL)

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Pathogens and Infections

Microorganisms that cause disease are called pathogens.

Bacteria can reproduce rapidly in the body and produce toxins (poisons) which make us feel ill.

Viruses reproduce within the body cell then destroy it.


He discovered that doctors ere transferring diseases to pregnant women from dead bodies. He made all doctors wash their hands when going between rooms.

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Fighting Infections

White bllo cells, called phagocytes, surround and ingest bacteria.

Lymphocytes produce chemicals called antibodies. the antibodies group round and stick to the pathogen.

Some lymphocytes produce antitoxins, these stick to and kill toxins.

Antibodies and antitoxins are specific.

Antibodies have a specific shape so that it can stick to the bacteria and kill it.

Each shape only fits one type of pathogen.

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Drugs Against Disease

Antibiotics are drugs that help to fight and kill the bacteria in your body.

Antibiotics dont work against all types of bacteria.

To find what antibiotic works well, a jelly is spread with bacteria and small paper discs are soaked in antibiotics and placed into the dish.

Drugs must be pescribed by doctors as some can become addictive and make the bacteria resistant to that drug.

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Antibiotic Resistance

Bacteria do not become resistant on purpose.

When a new strain of antibiotic-resistant bacteria emerge, we need to find a new antibiotic to kill it.

To reduce the chance of new strains forming, we need to reduce the use od antibiotics.

Whenever antibiotics are used it gives an advantage to any mutant bacterium.

MRSA (Methicillin-resistant staphylococcus aureus) is sometimes a superbus as it is resistant to most antibiotics.

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Children have an MMR vaccine to make them imune to measels, mumps and rubella

A dead or weak pathogen is injected and the white blood cells attack and remember how to make that antibody.

New infectous diseases appear when a mutation occurs in the bacteria or viruses.

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Growing Bacteria

The microorganisms growing on the nutrient medium are called a culture.

You should use a sterile technique to stop unwanted microorganisms entering the medium.

All equipment including the medium should be sterilsed before use.


The dish containing agar should be sealed with tape.

The cultures should be keps at a temp. of lower than 25 degrees.

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great help :)

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