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Obtaining Energy

Obtaining Energy. D. Crowley, 2007. Obtaining Energy. To know how humans obtain energy. Energy. Why do we need to eat food? Food is required by the body, along with oxygen, so that cells can respire Respiration occurs in every cell – it is the process of releasing energy

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Obtaining Energy

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  1. Obtaining Energy D. Crowley, 2007

  2. Obtaining Energy To know how humans obtain energy

  3. Energy • Why do we need to eat food? • Food is required by the body, along with oxygen, so that cells can respire • Respiration occurs in every cell – it is the process of releasing energy • Every cell in our body respires, converting this food (glucose) into energy (needed for growth; repair; movement etc…) glucose + oxygen → water + carbon dioxide + (energy)

  4. Do Some Work • Remember, energy gives us the ability to ‘do some work’ • Petrol (fuel for cars) releases energy when it combusts, allowing the car to move • Nuclear power releases vast amounts of energy, powering cities • Animals eat their fuel (food) which releases energy so the animal can ‘do some work’ • This ‘work’ could be moving; repairing; growing etc…

  5. Energy • Different foods have different amounts of energy in them – this is measured in kilojoules (kJ) and calories (cal) • This information is shown on the labels of foods, as well as showing you what is contained within them • What nutrients (types of food) can be present? • Fat • Carbohydrates (sugar / starch levels) • Protein • Vitamins • Minerals • Fibre • Water • They also tell you what has been added to the food – e.g. preservatives; additives; stabilisers etc…

  6. Biscuit Practical • In the previous lesson we looked at burning 3 different biscuits • We found that some biscuits raised the temperature of a test tube of water higher than others. Can you explain why this is?! • Each of the three biscuits had a different recipe – each type contained a different amount of sugar • When we placed the biscuits in the Bunsen burner they burnt at different rates – releasing different amounts of energy • The more energy they released, the hotter the water temperature became (more energy was transferred from the biscuit to the water)

  7. Task • Using pages 110 - 111 exploring science 7, read and answer questions 1 - 6

  8. Task 1. If we don’t get enough energy from food we will get thinner and ill, and potentially die • If we eat too much we store the extra energy as fat (which can potentially lead to becoming obese) 2. Joules (J) and kilojoules (kJ) measures energy - 1kJ = 1000J • 100g pasta contains 1463kJ • 320g pasts contains 1463 x 3.2 = 4682kJ • 100g Mars bar contains 2004kJ • Bigger bodies need more energy (for growth; repair; movement etc) • Pregnant women need energy for themselves and their baby

  9. Task 5. Baby; 11 year old child; secretary; fireman • All depends on the amount of work they do (and their size) • 5 year old needs 6000kJ of energy Pasta = 14.63kJ energy per 1g 6000/14.63 = 410.12g needs to be eaten • 5 year old needs 6000kJ of energy Mars bar = 1303kJ energy per bar 6000/1303 = 4.6 bars need to be eaten

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