Welcome to biology

1. Miss Tagore Welcome to biology

2. Biology Lesson 1 – Learning Intentions • Understand why we study science. • Describe the stages of the scientific method. • Describe the standardised way of measuring mass, length and volume. • State that this system is called the metric system.

3. Why do we study science? • The word science comes from the Latin "scientia“, meaning knowledge. Galileo before the Holy Office, a 19th century painting by Joseph-Nicolas Robert-Fleury

4. The scientific method • 1. Observationand descriptionof a phenomenon or group of phenomena. • 2. Formulation of an hypothesisto explain the phenomena. • 3. Use of the hypothesis to predict the existence of other phenomena, or to predict quantitatively the results of new observations. • 4. Performance of experimentaltestsof the predictions by several independent experimenters and properly performed experiments.

6. The Metric system

7. Mass – What does it actually mean? • Mass measures how much “stuff” there is in an given area or volume. • Mass is measured in: • grams (g) and; • kilograms (kg).

8. Volume • The amount of 3-dimensional space an object occupies. Capacity. • Metric units of volume are: • cubic centimeters (cm3); • cubic meters (m3) and; • Liters (l)

9. Length • Metric units of length are: • milimeters (mm) centimeters(cm) • meters (m) Kilometers(Km). 1Kilometer (km) = 1,000 meters (m) 1 meter (m) = 100 centimetres(cm) 1 centimetre(cm) = 10 milimeters (mm)

10. Making Metric Measurements • Copy and complete the table below – you must always draw tables with a ruler! • Using a meter stick, measure the dimensions of the table in meters. • Once you have recorded these dimensions, convert them into centimeters and millimeters.

11. Making Metric Measurements • Copy and complete the table below – you must always draw tables with a ruler! • Using a ruler, measure the dimensions of the test tube in centimeters. • Once you have recorded these dimensions, convert them into millimeters.

12. Making Metric Measurements • Copy and complete the table below – you must always draw tables with a ruler! • Collect a test tube and fill it right to the top. • Using a measuring cylinder, carefully measure out the volume of water and record volume to the nearest millimeter.

13. Why Metric? • The metric system is used in science because • It is used by the whole world, America is the exception! • It is easier to work with numbers that are multiples of ten.

14. Converting between metric units • For any two metric units, you convert from the larger unit to the smaller by multiplying by one of 10, 100, 1000 etc. • The reverse is also true; you can convert from a smaller unit to a larger by dividing by one of 10, 100, 1000 etc. • Have a look at the following examples see how this works:

15. Units of Volume Litres and Millimetres 1 litre = 1000ml 1.68 litres = 1680ml x1000 ÷1000

16. Units of Volume Metres and Millimetres 1 m = 1000mm 2.6m = 2600mm x1000 ÷1000

17. Units of Volume Centimetres and Millimetres 1 cm=10mm 31.5cm =315mm x10 ÷10

18. Units of Length Kilometres and Meters 1 km = 1000m 0.75km = 750m x1000 ÷1000

19. Units of Mass Kilograms and Grams 1 kg = 1000g 3.5kg = 3500g x1000 ÷1000

20. Over to you… • Collect a problem sheet on metric conversions and complete it to the best of your ability. http://www.homeschoolmath.net/worksheets/measuring.php

21. The Light Microscope Eye piece Lens Focusing wheel Stage Fine focus Diaphragm Light source Base

22. Practical task 1 – using a light microscope • Apparatus: • Compound light microscope • Microscope slide • Cover slip • Newspaper/magazine • Dropper • Water

23. Practical task 1 – using a light microscope • Get into pairs or groups of three. • With your partner, prepare a slide each using the letter “e” that you have cut out. • Look at your slides under the microscope at the different powered lenses. Remember to start with the lowest magnification and work your way up. • Make a sketch of what you see at all magnifications. Make sure that you label your diagrams with the appropriate magnification.

24. Tips for drawing microscope specimens • Draw a circle to represent the circle of light you see through your microscope (called the field of view). • Under the circle, write the total magnification you are using to view the specimen. • Then draw what you see within that circle. • Make sure what you draw is in proportion to the circle. For example, if what you see only takes up half the space of the circle, don’t make it the full size of the circle in your drawing. • Do not draw all of the specimen if you can only see part of it.

25. Why the letter e? • We use the letter e because it demonstrates very clearly what a microscope does to the orientation of the specimen that you are looking at. • The image is reversed • And • The image is inverted. • Thus the entire image is both reversed and inverted

26. Practical task 2 – using a light microscope • Apparatus: • Compound light microscope • Microscope slide • Cover slip • Iodine solution • Mounting needle • Small section of onion skin

27. Practical task 2 – using a light microscope • Get into pairs or groups of three. • With your partner, prepare a slide with a section of onion skin as demonstrated by your teacher. • Look at your slides under the microscope at the different powered lenses. Remember to start with the lowest magnification and work your way up. • Make a sketch of what you see at all magnifications. Make sure that you label your diagrams with the appropriate magnification. • Label the structures of the cell that you can see. You should be able to label at least three.

28. Points to consider • Now that you have completed your practical, look at your drawings at each magnification. • The cells that you can see in each diagram is known as the field of view (fov). Consider the following questions: • Are the number of cells different in each fov? • If so, can you think of an explanation for this? • Are you able to see all the structures of a plant cell? Give a reason for your answer. • The smallest units we have discussed so far are millimetres. Are these units suitable for microscopy?

29. Structures that you see with a light microscope Structures that you do not see but are actually there!

30. Units used in microscopy • The cells and their compounds like cell organelles are measured in terms of the fractions of a millimetre, because of their extremely small size. • The commonly used terminologies for these units are micrometres and nanometres

31. Micrometres(µm) • A micrometre or micron is one thousandth of a millimetre 1mm = 1000 µm 0.1mm = 100 µm 0.01mm = 10µm 0.001mm = 1 µm

32. Nanometres(nm) • A nanometre or is one thousandth of a micrometre. 1µm = 1000 nm 0.1µm = 100 nm 0.01µm = 10 nm 0.001µm = 1 nm

33. Cell Structure and Function • All living things are composed of cells; • Cells are the basic units of structures and function in living things; • All cells come from preexisting cells.

34. Eukaryotic cells • Eukaryotic cells include both plant and animal cells. • They are referred to as eukaryotic because they contain membrane bound nuclei.

35. Prokaryotic Cells • Prokaryotic cells include bacteria and their relatives. • These are usually unicellular organisms. • They are referred to as prokaryotic because they do not contain a membrane bound nucleus.

38. Cell Structures • Golgi apparatus: • Packages and secretes complex molecules.

39. Cell Structures • Secretory vesicles: • Move to the surface of a cell and discharge their contents

40. Cell Structures • Mitochondria: • Site of aerobic respiration.

41. Cell Structures • Chloroplasts: • Site of photosynthesis.

42. Cell Structures • Smooth endoplasmic reticulum: • Large surface area for transport of lipids.

43. Cell Structures • Rough Endoplasmic Reticulum (Rough E.R.) • Large surface area for transport of proteins.

44. Cell Structures • Ribosomes: • Site of protein synthesis.

45. Cell Structures • Nucleus: • Controls cell activities. • Contains DNA and mRNA. Nuclear envelope Nucleolus Nuclear pore

46. Cell Structures • Centrioles: • Involved in spindle fibre formation in meiosis/mitosis

47. Cell Structures • Lysosomes • Contains powerful enzymes which digest redundant structures.

48. Cell Structures • Cytoplasm: • Fluid in which many chemical reactions take place.