2. How small can you see? Most people can only see objects that are larger than 0.1mm. We can say that the resolving power of the human eye is about 0.1mm

3. Resolution The ability of the eye (or any other image-making instrument) to distinguish between separate objects that are close together. E.g. See the spots in figure D, compared to E.

4. The Cell Most cells are smaller than 0.1mm. A few like the paramecium, are barely visible to the human eye. Approximately five paramecium could fit on the period at the end of a sentence in a textbook. No small wonder they went unobserved for so many years!

5. Micro-organisms …Microscope… In order to discover micro-organisms, scientists needed a tool to extend the abilities of human vision. They needed a microscope. Invented at the end of the sixteenth century. Early microscopes were used to observe organisms that people knew already existed. Early microscopes only magnified 50x their actual size.

6. Common First Microscope Observations Insect parts Plant seeds Sand grains

7. Robert Hooke Hooke didn’t make microscopes Looked at tree bark, cork Coined the term ''cell''

8. Antony van Leeuwenhook Self-taught scientist who introduced the world to the micro-universe. Reported observations on the microscope in 1670 Used a single lense microscope (quartz) that was no larger than the palm of your hand. Due to his ability to grind glass he could magnify items 500x greater. Built 450 microscopes in his career, only 9 remain today.

9. The Modern Compound Light Microscope 19 th century saw improvements in glass- making techniques allowing lens-makers to remove distortion effects and coloured halos that plagued earlier microscopes. Ability to produce microscopes that magnified 2000x greater. Many of the cells that we will observe in Biology 11 were discovered during this time period.

10. Chlamydomonas (magnified 180x) – this organism makes its own food by photosynthesis. It moves by means of two long, whiplike structures called flagella

11. Euglena – like the previous slide, this organism photosynthesizes and moves by means of a single flagellum.

12. Paramecium – a paramecium is covered with short hairlike structures called cilia. The cilia are used for both movement and for sweeping food into a tiny groove that is similar to a mouth.

13. Stentor – this organism produces stalks that attach it to the bottom of ponds and streams, where it waits for food. A stentor has cilia, like the paramecium, but uses these structures for bringing in food rather than for movement.

14. Diatoms – these free-floating organisms vary in shape, produce shells around themselves, and photosynthesize.

15. Diatoms – the jewlery boxes of the sea!

16. Volvox – many volvox live together in a spherical colony. Each member of the colony has its own flagellum and makes its own food by photosynthesis.

17. 1. To carry a microscope, always use one hand to hold the arm and your other hand to support the base. 2. To keep the lens clean, never touch their surfaces with your fingers. Use only lens tissue (Kimwipes) to clean their surfaces. 3. Do not adjust any of the focussing knobs until you are ready to use the microscope.

18. continued… 4. Always focus using the coarse adjustment knob first, with the low-power objective lens in position. 5. Do not use the coarse adjustment knob when either the medium-power lens or high-power objective lens is in position. 6. Cover the microscope when it is not in use, or store in the appropriate cupboard after finishing.

19. In the Lab…