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Lesson Starter

Lesson Starter. Where do we gain our energy from? Why do we need this energy? What are the main food groups? How do plants gain energy?. Lesson Starter. What are the three main food groups? What does you body need energy to do? What foods do you think are particularly high in energy?.

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Lesson Starter

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  1. Lesson Starter Where do we gain our energy from? Why do we need this energy? What are the main food groups? How do plants gain energy?

  2. Lesson Starter • What are the three main food groups? • What does you body need energy to do? • What foods do you think are particularly high in energy?

  3. Learning Intentions To learn about energy gain and its use in humans Success criteria • State how the human body gains energy. • State what the body uses energy for. • State that food products contain different quantities of energy.

  4. Energy for Life • Your body uses energy all the time • When it grows • When your muscles move • To keep warm • We gain this energy from food!

  5. Think! Discuss with your partner- • Do all food products contain the same quantity of energy? • What food products are high in energy?

  6. Energy from food All foods contain energy. Some foods contain more energy than others but it is important to eat a variety of foods and to maintain a healthy, balanced diet.

  7. http://www.twigonglow.com/films/balanced-diet-1629/

  8. Carbohydrates • Carbohydrates are the most important source of energy for our bodies. • Our digestive system changes carbohydrates into glucose, blood sugar. • Simple carbohydrates include fruit, vegetable and milk products. • Complex carbohydrates include whole-grain bread, starchy vegetables and cereals • What type of energy does food contain? • What are the units energy is measured in?

  9. Energy table http://www.twigonglow.com/films/what-is-a-calorie-1384/

  10. Learning Intentions To learn about the use of energy in humans Success criteria • State how the human body gains energy. • State what the body uses energy for. • State that food products contain different quantities of energy.

  11. Energy from food What type of energy does you body change the energy from food into? Can you write an energy transfer equation to show this energy transfer? How can we prove that food contains energy?

  12. Lesson Starter • Where do humans gain energy from? What is this energy required for? • In what form is this energy? • What energy conversions take place in humans? • Describe the experiment which can be used to discover the energy content of food products?

  13. Burning food experiment Aim To investigate the energy content of different food products Result Copy this table into your jotter:

  14. Method Thermometer • Measure out 20 cm3 of cold water into a large test-tube • Record the temperature of the water in the table • Use a lit Bunsen burner to start the food burning • Hold the burning food under the test tube • When the food has finished burning record the temperature again • Work out the rise in temperature Water

  15. Questions • Which sample of food has the most energy? • Why is it important that all of the samples are of roughly the same weight? • What energy change is taking place in this activity? Conclusion • Food contains large quantities of chemical energy that can be released by burning

  16. Lesson Starter Burning food experiment: • How do you think the experiment could have been improved to minimise heat loss? • Was the experiment fair? (Remember in this experiment the only change should have been the food product)

  17. Where does food come from? Decide on your favourite meal! Write it down and then trace back to where your food comes from.

  18. Lesson Starter • What type of energy is stored in food? • What energy conversions take place in the human body? • What can all food be traced back to? • Trace Macaroni Cheese back to its source

  19. The origins of food • All food can be traced back to a green plant • Green plants make the foods that animals depend upon • videos\Food chain(ScsEye).mpg

  20. Food Chains

  21. Summary – energy in food • Your body uses energy all of the time to grow, move around and keep warm • You obtain energy by eating foods • All food can be traced back to a green plant • All plants get their energy from the sun by converting light energy into food in a process called photosynthesis • All animals depend on plants and/or other animals for their energy

  22. Quiz • How do humans gain energy? • What are the three ways in which we use this energy? • What unit is used to describe the energy content in food? • Where can the origin of all food products be traced back to? • Describe the experiment which shows the energy content in food? • What do plants require to survive? • What is the process called where plants make their own food

  23. Photosynthesis

  24. Lesson starter- What can you remember about photosynthesis? • What do plants require for photosynthesis to occur? • What was the name of the sugar they produce? • What important gas do they release during photosynthesis? Why is it important to humans?

  25. Green Plants as Producers. • All green plants are producers. • They make food (glucose) by the process of Photosynthesis, using light energy from the sun. • They use this as their own source of chemical energy. • They make sufficient extra to be the source of chemical energy for animals - consumers.

  26. Photosynthesis The diagram opposite gives the basic outline of the process of photosynthesis. The final product is in fact the sugar glucose, but this is normally converted to starch for storage in the leaves.

  27. Carbon + water + light energy glucose + oxygen dioxide Useful product Raw Materials Waste product Absorbed By chlorophyll

  28. Lesson Starter • What was the aim of the experiment we carried out last day? • What chemical did we use to test for the presence of starch? • What colour change occur to show that starch was present? • What can we therefore conclude is required for photosynthesis to be carried out by a green plant?

  29. Testing for Starch To see if a plant has been photosynthesising sucessfully, we can test its leaves for starch using Iodine Solution. This chemical turns from brown to blue/black if starch is present. You can test leaves from a number of plants that have been growing in different conditions. This will help you prove that plants need light, carbon dioxide and chlorophyll for photosynthesis.

  30. Experiment to test a leaf for photosynthesis • Collect a bunsen burner, a ceramic mat, a tri-pod stand, a dimple tile and a beaker filled with 100 cm3 of water. • Using a cork borer, cut out a leaf disc. (Half of class with use leaf from dark, other half leaf in the light). • Place the leaf disc into the beaker of water and leave it to boil. Once the water is boiling leave it for one minute (to burst cell membrane). • Turn the Bunsen burner off!!!

  31. Add approximately two finger widths of alcohol to a test tube. • Remove the leaf disc from the boiling water and place it into the test tube containing the alcohol. • Place the test tube containing the leaf disc back into the very hot water. • Once the disc has become colourless remove it and rinse the leaf in the beaker of hot water (to soften it). • Place the leaf into a cavity tile and test for the presence of starch using iodine solutions.

  32. Testing a Leaf for Starch • Place the leaf in boiling water. Why? • Place it in heated alcohol. Why? • Rinse in water. Why? • Test the leaf for starch. How?

  33. Testing a leaf for starch • Add Iodine solution to a decolourised leaf. Why? • If the colour changes from: • _________ _______ Starch is present.

  34. No starch starch The Need for Light Lightproof Box Healthy, well cared for plant in full illumination. Control Experiment Previously destarched plant, kept in dark. Tested one week later. Leaves tested for starch

  35. Conclusion- It can be concluded that light energy is required for photosynthesis to occur and starch to be produced.

  36. Lesson starter • How would you set up an experiment to show that plants require carbon dioxide for photosynthesis? • Think about the experiment we carried out to show that light was required for photosynthesis (and information from the video).

  37. No starch starch The Need for Carbon Dioxide Air minus Carbon Dioxide Normal air Sealed bell jar Experiment Control Healthy, well cared for plant in full illumination for a week Plain water KOH solution removes Carbon Dioxide from the air. Leaves tested for starch

  38. Investigating photosynthesis in the presence and absence of light  = positive result for starch  = negative result for starch

  39. Experiment to test a leaf for photosynthesis • Collect a bunsen burner, a ceramic mat, a tri-pod stand, a dimple tile and a beaker filled with 100 cm3 of water. • Using a cork borer, cut out a leaf disc. (Half of class with use leaf from dark, other half leaf in the light). • Place the leaf disc into the beaker of water and leave it to boil. Once the water is boiling leave it for one minute (to burst cell membrane). • Turn the Bunsen burner off!!!

  40. Add approximately two finger widths of alcohol to a test tube. • Remove the leaf disc from the boiling water and place it into the test tube containing the alcohol. • Place the test tube containing the leaf disc back into the very hot water. • Once the disc has become colourless remove it and rinse the leaf in the beaker of hot water (to soften it). • Place the leaf into a cavity tile and test for the presence of starch using iodine solutions.

  41. Investigating photosynthesis in the presence and absence of Carbon dioxide  = positive result for starch  = negative result for starch

  42. Conclusion- It can be concluded that Carbon dioxide is required for photosynthesis to occur and starch to be produced.

  43. Variegated Leaves Why do you think some areas of this leaf are white? What do the white cells not contain?

  44. Testing for the presence of starch on a variegated leaf

  45. Light Glass plate (heat sink) gas Lamp Metre stick Aquatic plant Water Photosynthesis – To examine which gas is given off during photosynthesis

  46. Lesson Starter-Elodea Bubbler • Why is the following apparatus used: • The test tube? • The lamp? • The filter funnel? • The water?

  47. Lesson Starter • How would you set up an experiment to record the rate of photosynthesis? • What is the test for the presence of oxygen? • Why are plants important?

  48. Testing the gas given off in photosynthesis • How could you prove the gas given off is oxygen? What is the test for oxygen gas? Oxygen will relight a glowing splint

  49. Demonstrating Oxygen is Produced by Plants Oxygen Gas Test Tube Funnel Pond weed • How would we test to see if it is oxygen?

  50. What conditions do you think may affect the rate of photosynthesis? • Carbon dioxide concentration • Light intensity • temperature

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