Biology AQA Unit 1 GCSE Pages 2-6

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Section 1

Question Answer
What does a healthy diet have? What are used by the body to release energy and to build cells?A healthy diet has the right balance of food types. Carbohydrate, fat and protein are used by the body to release energy and to build cells.
Why are mineral ions and vitamins needed? What can happen if the diet is unbalanced?Mineral ions and vitamins are needed to keep the body healthy. If the diet is unbalanced a person can become malnourished.
What happens to your body if you take in too much energy or too few vitamins?Your body can become malnourished.
What happens if you excersise? What does excersise increase and what does this mean?If you excersise, more energy is used by the body. Excersise increases the metabolic rate, which means the chemical reactions in cells work faster.
What two things can also affect your metabolic rate?The proportion of muscle to fat in your body and your inherited factors can also affect your metabolic rate.
Why do different people need different amounts of energy?Different people need different amounts of energy because the metabolic rate varies from person to person.
Give some sources of saturated fat?Meat, dairy, eggs
Sources of unsaturated fat?Olive oil, peanuts, margarine
What is the proportion of fruit and vegetables in a balanced diet?The proportion of fruit and vegetables is 1/3 of a balanced diet.
What is your metabolism and your metabolic rate?The chemical reactions in your body that keep you alive are called your metabolism, and the rate at which they occur is your metabolic rate.
What is important for good health?It is important for good health to get the energy balance correct.
What happens if the energy you take in equals the energy you use? What can eating too much food lead to?If the energy you take in equals the energy you use then your mass will stay the same. Eating too much food can lead to becoming overweight and obese.
What can long-term obesity lead to?Long-term obesity can lead to severe health problems including Type 2 diabetes (high blood sugar).
How can these problems be reduced?These problems can be reduced by eating less carbohydrate and increasing the amount of excersise.
Why are some people unhealthy?Some people are unhealthy because they have too little food (starvation). They find it difficult to walk about and may suffer from deficiency diseases due to lack of vitamins and minerals.

Section 2

Question Answer
What can your metabolic rate be affected by?Your metabolic rate can be affected by the genes you inherit from your parents.
How many types of cholestrol are there and what are they?There are two types of cholestrol, 'good' and 'bad' cholestrol.
What do you need 'good' cholestrol for?You need 'good' cholestrol for your cell membranes and to make vital substances.
What do small numbers of the population inherit and what can it do?Small numbers of the population inherit high levels of 'bad' cholestrol, which can lead to heart disease.
What can foods rich in saturated fat do?Foods rich in saturated fat can also increase blood cholestrol levels.
What can also increase blood cholestrol levels?Foods rich in saturated fat can also increase blood cholestrol levels.
What can a person do by excersising regularly?By excersising regularly a person can increase their metabolic rate and lower high cholestrol levels.
Muscle needs more energy than fat?Muscle needs more energy than fatty tissue, which means (all other things being equal) people with a higher proportion of muscle to fat in their bodies will have a higher metabolic rate.
Why does eating too much make you put on weight?The food contains energy, and any excess energy is stored in the body as fat.
What can pathogens cause?Pathogens cause infectious diseases.
What are pathogens?Pathogens are tiny microorganisms - usually bacteria or viruses.
What happens when bacteria or viruses enter the body? How can they make you feel ill?When bacteria and viruses enter the body they reproduce rapidly. They can make you feel ill by producing toxins (poisons).
Size of viruses in comparison to bacteria? Where do they reproduce?Viruses are much smaller than bacteria and reproduce inside cells. The damage to the cells also makes you ill.
What did a doctor called Semmelweiss realise before bacteria and viruses had been discovered?Before bacteria and viruses had been discovered, a doctor called Semmelweiss realised that infection could be transferred from person to person in a hospital.
What did Semmelweiss do?Semmelweiss told his staff to wash their hands between treating patients. However, other doctors did not take him seriously. We now know that he is right.

Section 3

Question Answer
What does the skin do to help defend you?The skin prevents pathogens getting into the body.
Name two other ways in which the body defends against pathogens?Pathogens are also trapped by mucus and killed by stomach acid.
What are white blood cells part of?White blood cells are part of the immune system.
What three things to white blood cells do to defend the body?They can ingest pathogens. This means they digest and destroy them. They produce antibodies to help destroy particular pathogens. They produce antitoxins to counteract the toxins (poisons) that pathogens produce.
What do antibiotics do?Antibiotics kill infective bacteria in the body.
What is Penicillin and who was it first discovered by?Penicillin is an antibiotic, but there are many others. It was first discovered by Alexander Fleming in 1928.
Why are viruses difficult to kill?Viruses are difficult to kill because they reproduce inside the body cells, so any treatment could also damage the body cells.
What do painkillers do and not do?Painkillers and other drugs relieve the symptoms of a disease but do not kill the pathogen.
What will your immune system do?Your immune system will usually overcome the viral pathogens.
Why are antibiotics only able to kill bacteria?Viruses are inside the body cells.

Section 4

Question Answer
What can bacteria be grown on?Bacteria can be grown on agar jelly.
What can pure cultures of non-pathogenic (safe) bacteria be used for?Pure cultures of non-pathogenic (safe) bacteria can be used for laboratory investigations.
What can a culture of microorganisms be used to find the effects of?A culture of microorganisms can be used to find the effect of antibiotics on bacteria.
What do investigations need?Investigations need uncontaminated cultures of microorganisms. Strict health and safety procedures are used to protect yourself and others.
What might contamination come from?Contamination might come from your skin, the air, the soil or the water around you.
What could happen if the culture is contaminated?If the culture is contaminated other bacteria could grow, including pathogens.
What does air contain and what needs to be done about it?Air contains microorganisms. To keep a bacterial culture pure, the microorganisms from the air must be killed or prevented from entering the culture.
What must you do to culture (grow) microorganisms in a laboratory?Give them a liquid or gel containing nutrients - a culture medium. It contains carbohydrates as an energy source, various minerals and sometimes other chemicals. A culture medium called agar jelly is used. Provide warmth and oxygen. Keep them incubated at 25 degrees celsius in school laboratories and at 35 degrees celsius in industry.
Why do industrial laboratories use 35 degrees celsius instead of 25 degrees celsuius as in schools?The bacteria will grow at a faster rate.
What must you do to keep the culture pure?Kill all the bacteria on the equipment - pass metal loops through a flame; boil solutions and agar. Prevent microorganisms from the air getting into the equipment.
How to culture microorganisms safely in a laboratory step 1 of 3.Sterilise the inoculating loop used to transfer microorganisms to the agar by heating it until it is red hot in the flame of a Bunsen and then letting it cool. Do not put the loop down or blow on it as it cools.
How to culture microorganisms safely in a laboratory step 2 of 3.Dip the sterilised loop in a suspension of the bacteria you want to grow and use it to make zigzag streaks across the surface of the agar. Replace the lid on the dish as quickly as possible to avoid contamination.
How to culture microorganisms safely in the laboratory step 3 of 3.Seal the lid of the Petri dish with adhesive tape to prevent microorganisms from the air contaminating the culture - or microbes from the culture escaping. Do not seal all the way around the edge so oxygen can get into the dish and harmful anaerobic bacteria do not grow.

Section 5

Question Answer
What can some pathogens do?Some pathogens, particularly viruses, can mutate (change) resulting in a new form called a mutation.
Are people immune to these changes?Very few people are immune to these changed pathogens so disease can spread quickly.
What do diseases that spread within a country result in?Diseases that spread within a country result in an epidemic. Those that spread across countries result in a pandemic.
Why do some pathogens spread rapidly?Very few people are immune to the new pathogen.
What is the MRSA 'superbug'?The MRSA 'superbug' is a bacterium that has evolved through natural selection. MRSA and other bacteria have become resistant to the common antibiotics.
What do mutations of pathogens produce?Mutations of pathogens produce new strains, some are resistant to antibiotics.
What do antibiotics do with regards to strains?Antibiotics kill individual pathogens of the non-resistant strain.
What happens to the resistant bacteria?The resistant bacteria survive and reproduce and a whole population of a resistant strain develops. This is natural selection.
What should antibiotics not be used for?Antibiotics should not be used for mild infections in order to slow down the rate of development of resistant strains.
What are dead or inactive forms of a pathogen used to make?Dead or inactive forms of a pathogen are used to make a vaccine. Vaccines can be injected into the body.
How do the white blood cells react to vaccines?The white blood cells react by producing antibodies. This makes the person immune. It prevents further infection because the body responds quickly by producing more antibodies.
What do the antibodies recognise?The antibodies recognise the antigen ( the protein shape ) on the pathogen.
What is the MMR vaccinatina and why is it given?The MMR vaccination (immunisation) is one of several vaccines. MMR is given to prevent measles, mumps and rubella.