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Welcome to Biology

Welcome to Biology. Increasing reliability. A drug company wants to test the effectiveness of a new drug against asthma. How can they increase the reliability of their results?. Increasing reliability.

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Welcome to Biology

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  1. Welcometo Biology

  2. Increasing reliability A drug company wants to test the effectiveness of a new drug against asthma. How can they increase the reliability of their results?

  3. Increasing reliability A drug company wants to test the effectiveness of a new drug against asthma. How can they increase the reliability of their results? Use a large test group of asthmatics (1000 +) Have a mixed group (ages, gender & fitness levels) Use the same number & mix in the control group Give the control group a placebo Run the trial over a long period Swap the groups over and repeat the trial Repeat the trial with another group Get someone else to replicate the trial Measure accurately and often changes in incidence of asthma & any side effects, etc

  4. Milk bubbles experiment For Part A, identify the: • Hypothesis • Independent variable • Dependent variable • Control • Variables you controlled • How you increased reliability For Part B, you’ll need to identify these before you design & carry out your experiment

  5. Milk bubbles experiment For Part A, identify the: • Hypothesis – skim milk will produce smaller bubbles than full cream milk • Independent variable – the type of milk • Dependent variable – size of bubbles • Control – full cream milk • Variables you controlled –temperature, volume of milk, strength of blowing, etc • How you increased reliability – repeat experiment, replicate experiment, etc For Part B, you’ll need to identify these before you design & carry out your experiment

  6. Reviewing graphs

  7. Reviewing graphs

  8. Interpreting graphs

  9. Parts of the microscope

  10. Parts of the microscope Ocular lens Arm Objective lens Stage Iris wheel diaphragm Coarse focus Light Fine focus

  11. Using the microscope • Changing the magnification • Changing the focus • Adjusting the light or contrast

  12. Using the microscope • Changing the magnification • Changing the focus • Adjusting the light or contrast

  13. Calculating magnification • x10 ocular lens and x4 objective lens = • x10 ocular lens and x10 objective lens = • x10 ocular lens and x40 objective lens =

  14. Calculating magnification • x10 ocular lens and x4 objective lens = x40 • x10 ocular lens and x10 objective lens = x100 • x10 ocular lens and x40 objective lens = x400

  15. Working distance This is the distance between the objective lens and your slide. The higher the magnification of the lens, the larger the lens The higher the magnification of the lens, the smaller the working distance

  16. What you see under the microscope Everything is reversed as well as magnified

  17. What you see under the microscope 2 • If the object appears to be at the top of the slide it is really You need to move the slide • If the object appears to be at the left of the slide it is really You need to move the slide

  18. What you see under the microscope 2 • If the object appears to be at the top of the slide it is really at the bottom You need to move the slide towards you • If the object appears to be at the left of the slide it is really on the right You need to move the slide to the right

  19. Diameter of field of view • Distance across centre of field • Measured with • Measured in

  20. Diameter of field of view • Distance across centre of field • Measured with a minigrid • Measured in micrometres (m)

  21. Millimetres and micrometres • 1 mm = m • 2.4 mm = m • 340 m = mm • 4400 m = mm

  22. Millimetres and micrometres • 1 mm = 1 000 m • 2.4 mm = 2 400 m • 340 m = 3 400 mm • 4400 m = 4 400 mm

  23. Using a minigrid

  24. Magnification and field of view 1 x40 x100 x400

  25. Magnification and field of view 2 • As magnification increases, field of view • As magnification decreases, field of view

  26. Magnification and field of view 2 • As magnification increases, field of view decreases by the same factor • As magnification decreases, field of view increases by the same factor

  27. Magnification and field of view 3 If field of view at x100 is 1600 m, then • Field of view at x400 = • Field of view at x40 = If field of view at x400 = 200 m, then • Field of view at x100 = • Field of view at x40 =

  28. Magnification and field of view 3 If field of view at x100 is 1600 m, then • Field of view at x400 = 400 m • Field of view at x40 = 4 000 m If field of view at x400 = 200 m, then • Field of view at x100 = 800 m • Field of view at x40 = 2 000 m

  29. Size of objects under the microscope 1 If given a scale – 0 1 2 mm

  30. Size of objects under the microscope 1 If given a scale – 0 1 2 mm Measure object with ruler Measure scale with ruler Use scale to convert ruler measurement of object to real one Size = 0.6mm = 600 µm

  31. Size of objects under the microscope 2 If given a field of view – Magnification x100, field of view 2000 m

  32. Size of objects under the microscope 2 If given a field of view – Magnification x100, field of view 2000 m Measure object with ruler Measure field of view with ruler Use field of view measurement to convert ruler measurement of object to real one Size = 1000 m

  33. Size of objects under the microscope 3 If given a magnification – Magnification x 200

  34. Size of objects under the microscope 3 If given a magnification – Magnification x 200 Measure object with ruler Divide size by magnification factor to get real size Size = 4cm ÷ 200 = 0.02 cm = 0.2 mm = 200 m

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