B1- Biology- B1.1 - B1.10 (Keeping Healthy)

Key Points

• Most people eat a varieed fiet, which includes everything needed to keep the body healthy
• Different people nee different amounts of energy
• The metabolic rate varies from person to person
• The more exercise you take, the more food you need

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A balanced diet contains the correct amouns of:

• Carbohydrates 
• Proteins
• Fats
• Vitamins
• Minerals
• Fibre
• Water

• Your body uses Carbohydrates, proetins and fats to release the energy you need to live and build new cells
• You need small amount of vitamins and minerals for your body to work healthily.- Without them you may suffer from deficiency diseases
• Without a balanced diet you will be malnourished

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Examiners Tip!

'Metabolic rate' refers to the chemical reactions that take place in cells.

Key Points

• If you take in more energy than you use, you will store the excess as fat
• Obese people have more health problems than others
• People do not have enough to eat and can develop serious health problems 
• Exercise helps reduce weight and maintain health
• Your health is affected by having an unbalanced diet

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Examiners Tip

The word 'Malnourished' can be used to describe people who do not have a balanced diet. They may have too little food, or too much food in the wrong combination of foods.

Key Points

• Inherited factors affect our health. These include our metabolic rate and cholesterol level.
• People who exercise regularly are usually healtheir than people who take little exercise.

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Controlling Cholesterol

They way your body balances cholesterol is an example of how an inherited factor can affect your health

Cholesterol is needed for your cell membranes and to make vital hormones

Two forms of cholesterol are in your blood, one healthy, one not. More of the unhelthy cholesterol could lead to heart disease.

Key Points

• Infectious diseases are caused by microorganisms called pathogens, such as bacteria and viruses.
• Bacteria and viruses reproduce rapidly inside your body. Bacteria can produce toxins which make you feel ill.
• Viruses damage your cells as they reproduuce. This can also make you feel ill.
• Semmelweis recognised the importance of hand-washing in preventing the spread of infectious diseases in hospital.

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Difference Between Bacteria and Viruses

Bacteria are single celled living organisms- much smaller than animals and plants

Although some bacteria cause disease its normally very harmless and some are useful. They make yoghurts cheese and medicine

Viruses are even smaller than bacteria and are not cells. Have regular shapes cause disease in every type of living organism

Key Points

• Your body has several methods of defending itself against the entry of pathogens using the skin, the mucus of the breathingsystem and the clotting of the blood
• Your white blood cells help to defend you against pathogens by ingesting them, making antibodies and making antitoxins

Role of white blood cell

• Consuming microorganisms- Some white blood cells digest pathogens, destorying them so they cannot make you ill
• Producing antibodies- Every invading cell has unique antigens on the surface. When your white blood cell comes across a foreign antigen, it produces proteins called antibodies to kill invading cells.
• Antibodies are then rapidly produced rapidly and carried around the body to kill all similar bacteria
• Produces toxins which counteract the toxins produced by invading bacteria

Key Points

• Some medicines relieve the symptoms of diease but do not kill the pathogens which cause it
• Antibitoics cure bacteria diseases by killing the bacteria in your body
• Antibiotics do not cure viruses because viruses reproduce inside of the cells. It is difficult to destroy viruses without damaging your body cells
• Antibiotics kill bacteria- Antibodies are produced by white blood cells to kill bacteria

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Bacteria can become resistant to Antibiotics

• Bacteria can mutate- mutations cause them to becom resistant
• If you have an infection some of the bacteria may be resistant 
• Meaning when you treat it, only the non-resistant bacteria will be killed
• The resistant will survive and reproduce and the population will increase
• The resisant strain could cause a serious infection that antibiotics cant treat. E.g- MRSA
• To prevent resistance you should avoid your doctor over perscribing antibiotics for things like colds 

Key Points

• An uncontaminated culture of microorganisms can be grown using sterilised petri dishes and agar. You sterealise the inoculating loop before use and seal the lid of the petri dish to prevent unwanted microorganisms getting in. The culture is left in about 25°C for a few days
• Uncontaminated cultures are needed so we can investigate the effect of chemicals such as disinfectants and antibiotics on microorganisms.
• Cultures should be incubated at a maximum temprature of 25°C in schools and colleges to reduce the liklihood of harmful pathogens growing.
• Microorganisms are grown at 37 in the lab
• Microorganisms are killed at 100°

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Examiners Tip!

Make sure you understand why we sterilise. We boil solutions and heat-treat appartus in an autoclave to kill bacteria already in them. This is sterilising.

Key Points

• Many types of bacterium have developed antibiotic resistance as a result of natural selection. To prevent the problem getting worse we must not overuse antibiotics
• If bateria or viruses mutate, new strains of the pathogen can appear causing disease
• New strains of the diease which spread rapidly can lead to epademics and pandemics. Antibiotics and vaccinations may not be effective against the new strain

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Examiners Tip

Washing hands removes pathogens however it may not kill the pathogens on them

Key Points

• Your white blood cells produce antibodies to destory the pathogens. Then your body will respond rapidly to future infections of the same pathogen, by knowing which antibody to make. You then become immune to the disease
• You can be immunised against the disease by introducing small amounts of the dead or inactive pathogen into your body
• We can use vaccinations to prevent against viral and bacterial pathogens.

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Examiners Tip

High levels of antibodies do not stay in your blood forever

Immunity is the ability of your white blood cells to produce the right antibodies quickly if you are reinfected by a disease.

Key Points

• Vaccinations protect individuals and society from harmful diseases
• The treatments of disease have changed as our understanding of antibiotics and immunity has  increased