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Boardworks GCSE Science: Biology Health and Diet

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Presentation on theme: "Boardworks GCSE Science: Biology Health and Diet"— Presentation transcript:

1 Boardworks GCSE Science: Biology Health and Diet

2 Boardworks GCSE Science: Biology Health and Diet

3 Boardworks GCSE Science: Biology Health and Diet
A history of fad diets Boardworks GCSE Science: Biology Health and Diet Which diets are designed for weight loss? Which diets have a scientific basis?

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You are what you eat! Boardworks GCSE Science: Biology Health and Diet When food is digested its components enter the blood. carbohydrate glucose fat fatty acids + glycerol protein amino acids Molecules used for growth and repair become part of the body. Those used as energy sources are lost as CO2 and H2O.

5 What are cells made from?
Boardworks GCSE Science: Biology Health and Diet Different nutrients are incorporated into each part of a cell: membrane: fats and carbohydrate nucleus: protein cytoplasm: protein and water

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You are what you eat! Boardworks GCSE Science: Biology Health and Diet What could this food label represent? A human!

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Different nutrients Boardworks GCSE Science: Biology Health and Diet Teacher notes Small groups could be asked to discuss what they remember from KS3 and then elect a spokesperson to feed back to the rest of the class.

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Dietary guidelines Boardworks GCSE Science: Biology Health and Diet vitamins and minerals (1%) protein (14%) carbohydrate (50%) fat (35%) The amount of each type of nutrient a person needs varies between individuals. What factors might affect how much a person needs?

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Lack of protein Boardworks GCSE Science: Biology Health and Diet Proteins in meat and fish are called first-class proteins because they contain all the essential amino acids that humans need in their diet. Recommended daily allowance (RDA) of protein (g) = 0.75 x body mass (kg) What is the RDA of protein for a 60 kg student? RDA = 0.75 x 60 kg = 45 grams A protein deficiency illness called Kwashiorkor can cause a swollen belly and weak immune system, and is common in developing countries.

10 Why do some people need more food?
Boardworks GCSE Science: Biology Health and Diet Metabolism is the series of chemical reactions or ‘life processes’ in the body. Different amounts of energy are used in different life processes. digestion (10%) exercise and warmth (20%) growth and repair (70%) Metabolic rate is the rate at which cells uses energy, and this varies between individuals. Why does metabolic rate increase during exercise and cold weather?

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12 Chemical and physical digestion
Boardworks GCSE Science: Biology Health and Diet Teacher notes This four-stage animation illustrates the processes of physical and chemical digestion. Suitable prompts could include: What actually breaks the food down? Enzymes can only break down the food on the edge of a lump. What happens in the mouth to speed up digestion? Why is saliva so slimy? Some people say you can still swallow if you are hanging upside down. What do you think? What's the difference between physical and chemical digestion? The stomach lining can defend itself from acid but the small intestine cannot. How does your body neutralize stomach acid? Toxins like alcohol may be absorbed with the nutrients from your small intestine. What is the first organ the blood takes them to? What’s left to enter the large intestine once nutrients have been absorbed?

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Enzymes at work Boardworks GCSE Science: Biology Health and Diet Enzymes digest food in the mouth, stomach and small intestine. Enzymes break down large food molecules into smaller ones that can be absorbed by the blood. This is called chemical digestion. Different types of food are broken down by different enzymes.

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Enzymes of digestion Boardworks GCSE Science: Biology Health and Diet

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Helping enzymes Boardworks GCSE Science: Biology Health and Diet Enzymes are not the only substances involved in chemical digestion. Hydrochloric acid in the stomach provides the right conditions for protease enzymes to break down protein. Bile is a substance produced by the liver and stored in the gall bladder. It helps the digestion of fats by turning them into small droplets. This is called emulsification. How does this help lipase enzymes? The smaller droplets have a larger surface area, which speeds up the rate at which lipase digests the fat.

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Which enzyme? Boardworks GCSE Science: Biology Health and Diet Teacher notes This drag and drop activity could be used as a plenary exercise to check students’ ability to identify facts about digestive enzymes. Class voting or the use of coloured traffic light cards could be make this a whole-class exercise. Alternatively, students could be asked to complete the table in their books and the activity could be concluded by the completion on the IWB.

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What is BMI? Boardworks GCSE Science: Biology Health and Diet Body Mass Index (BMI) measures the relative amounts of fat and muscle in the body. BMI = body mass (kg) (height)2 (m) Gloria: 1.45 m and 66 kg BMI Conclusion BMI = 31 <20 underweight Zak: 1.85 m and 66 kg 20-25 normal BMI = 19 25-30 overweight >30 obese What are their health risks? Obese people have an increased risk of arthritis, diabetes and heart disease. People who are underweight tend to have poor immune systems and often get ill.

19 Are you right for your height?
Boardworks GCSE Science: Biology Health and Diet In 2002, 22% of boys and 28% of girls aged 2-15 in the UK were overweight or obese. Statistics show that obesity levels, among both young people and adults, are rising. Calculating a person’s BMI can be useful, but the formula can overestimate the proportion of body fat in people who are muscular. This is because muscle is denser than fat. Photo credit: Peter Werner Teacher notes Data on childhood obesity/overweight from International Obesity Taskforce (www.iotf.org) This means it is helpful to use extra measures to help judge how healthy a person is, such as waist circumference.

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What is blood pressure? Boardworks GCSE Science: Biology Health and Diet Blood pressure is a measure of the pressure exerted by the blood against artery walls. Blood pressure varies with: heartbeat strength health blood volume age. fitness Blood pressure is measured as two numbers, e.g. 120/80. What do these numbers show? Photo credit: Karen Barefoot The numbers show pressure readings in mm of mercury.

21 Systolic and diastolic
Boardworks GCSE Science: Biology Health and Diet “Blood pressure one-twenty over eighty.” The big number (‘120’) is the systolic pressure. This is the blood pressure during a heartbeat. The small number (‘8’) is the diastolic pressure. This is the blood pressure in-between heartbeats.

22 How does blood pressure affect health?
Boardworks GCSE Science: Biology Health and Diet High blood pressure can make blood vessels more likely to burst, and can cause strokes and kidney damage. Low blood pressure can cause dizziness, fainting and poor circulation. Age Systolic Diastolic The older you get, the higher your blood pressure naturally becomes. 10 80-100 60 15 90-110 60 20 70 40 80 Kevin is 38 years old and his blood pressure is 180/90. What advice would you give him?

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Lifestyle assessment Boardworks GCSE Science: Biology Health and Diet Kevin’s GP quizzed him about his lifestyle, tested his blood and referred him to a health centre. Excess salt is known to increase blood pressure in about 30% of the population. What else could Kevin do to improve his health?

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Health and fitness Boardworks GCSE Science: Biology Health and Diet Health and physical fitness are different. A healthy person is free from disease or abnormality. A fit person has good cardiorespiratory, aerobic and muscular endurance. Kevin’s GP wants his cardiovascular fitness to improve so that he puts less strain on his body. His personal trainer wants other sorts of fitness to improve. What types of exercise should Kevin do?

25 What is wrong with fast food?
Boardworks GCSE Science: Biology Health and Diet Fast food and takeaways such as curries, burgers and pizzas are high in unhealthy nutrients such as saturated animal fats, sugar and salt. Fast food usually contains very little fibre, vitamins, minerals or unsaturated vegetable oils, which are important for a healthy diet. Photo credit (top right): Jim Broughton Photo credit: (bottom left): Ede Bittle Teacher notes See the ‘Food Chemistry’ presentation for more information on fats and health.

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Unhealthy diets? Boardworks GCSE Science: Biology Health and Diet

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What is cholesterol? Boardworks GCSE Science: Biology Health and Diet Cholesterol is a lipid found in cell membranes and is used in the production of hormones and bile. Cholesterol is transported in the blood by molecules called lipoproteins, of which there are two types: high-density lipoprotein (HDL): often called ‘good cholesterol’ low-density lipoprotein (LDL): often called ‘bad cholesterol’. Cholesterol levels depend on diet and genes, but high levels of LDL have been linked to eating lots of saturated fats and few mono/polyunsaturated fats.

28 Good and bad cholesterol
Boardworks GCSE Science: Biology Health and Diet How do ‘good’ and ‘bad’ cholesterol affect a person’s health?

29 Cholesterol and heart disease
Boardworks GCSE Science: Biology Health and Diet Why is LDL called ‘bad cholesterol’? Excess LDL is deposited on the walls of blood vessels, which can lead to clots in the arteries. This can starve the heart of oxygen and cause heart disease. Why is HDL called ‘good cholesterol’? HDL returns cholesterol to the liver where it is metabolized. The risk of heart disease may be reduced by: lowering blood cholesterol eating more HDL than LDL gentle daily exercise.

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Taking action Boardworks GCSE Science: Biology Health and Diet Kevin’s blood test showed high cholesterol, but not high enough to require drug therapy to reduce it. This margarine claims to cut blood cholesterol by 10%, but it costs four times as much as normal margarine. Photo credit: Bruno Neeves Should Kevin buy the margarine? What extra information would help him decide?

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What are statins? Boardworks GCSE Science: Biology Health and Diet The plant extracts in margarine that lower cholesterol are less effective than cholesterol-lowering drugs called statins. Should these drugs be available without a prescription? Yes! People should be allowed to self-medicate. No! People with normal cholesterol might take them and they wouldn’t be checked for side-effects like liver damage. What do you think?

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Glossary (1/2) Boardworks GCSE Science: Biology Health and Diet blood pressure – The pressure in the arteries during and between contractions of the heart. body mass index – A measure of a person’s weight in relation to their height. chemical digestion – The process of breaking large food molecules into smaller ones using enzymes. fitness – Strength, stamina, flexibility, agility, speed and cardiovascular efficiency. health – Freedom from disease and injury. heart disease – An abnormal condition of the heart or the arteries that supply the heart.

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Glossary (2/2) Boardworks GCSE Science: Biology Health and Diet lipoproteins – Molecules that carry cholesterol in the blood and which are either high density or low density. metabolic rate – A measure of how fast chemical reactions occur in cells. obese – A person who is very overweight and has a BMI of over 30. physical digestion – The breaking up of pieces of food by chewing it in the mouth and churning it in the stomach. saturated – A type of animal fat that raises blood cholesterol levels and increases the risk of heart disease. unsaturated – A type of fat from vegetable and fish oils that helps lower blood cholesterol levels and reduce the risk of heart disease.

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Anagrams Boardworks GCSE Science: Biology Health and Diet

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Multiple-choice quiz Boardworks GCSE Science: Biology Health and Diet Teacher notes This multiple-choice quiz could be used as a plenary activity to assess students’ understanding of health and diet. The questions can be skipped through without answering by clicking “next”. Students could be asked to complete the questions in their books and the activity could be concluded by the completion on the IWB.


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