f2eb66b90c22sdfss5cf9f0652640c13c6f.pptx

cells

1. Keywords: Organisms Cell Microscope Observation State what a cells is. Describe the features of a light microscope. Explain how to use a microscope to observe a cell. Chapter 1 Part 1.1 Observing Cells ! P.14-15 Learning Objective : How do we use a light microscope to observe cells? DO NOW TASK : What is the smallest living thing you can think of? Can you see this living thing with your eyes? KS3 Activate Science

2. Foul fact! Look around you. Can you see any dust? Most household dust is actually dead cells. These come from anything living in your house. To see the cells, you need to look through a microscope .

3. What are living organisms made of? All living organisms are made up of cells , they are the building blocks of life. Cells are extremely small! they are the smallest units found in an organism. Organisms such as bacteria can be made of just one cell… humans are made of millions of cells! Fantastic Fact! Cells are so small that about 100 animal cells would fit across the width of this tiny full stop.

4. Which is the odd one out and why? Something to think about……

5. Magnifying lenses 1. Write your name and look at it with the lenses provided. 2. What has happened to the writing when you put your lens over it? 3. Why has this happened? Why is this useful?

6. Microscopes through time….. Robert Hooke (1635- 1703) invented the worlds first microscope and is still the most common design for the microscope now. With his microscope Hooke discovered cells in 1665. He looked down his microscope at a thin slice of cork and discovered plant cells . Cork is a type of tree bark .

7. This is the modern microscope that scientists and students use in laboratories. With the development of stains for specimens, better lenses and light sources todays best light microscopes magnify up to x1500 with resolutions down to 0.0001nm! You will learn now what each part of the microscope is called and how to use one. Looking carefully and in detail at an object is called making an observation. Microscopes through time…..

8. Features: Uses a beam of light to observe the sample; (lamp) Can magnify objects to approximately 2000 (two thousand) times. Has a resolution of approximately 200 nm (nanometres). The Light Microscope

9. 1. State what all living organisms are made up of. 2. Write down what Robert Hooke saw when he looked at cork using a microscope. 3. State what is meant by a scientific observation. 4. Name the part of a microscope you look down. ANSWERS: 1. Cells 2. Plant cells 3. Looking carefully and in detail at an object is called making an observation. 4. Eyepiece QUICK CHECK 1 : Observing cells

10. Eyepiece lens Magnification Objective lens Resolution The part of the microscope you look down. How much bigger something appears compared with its actual size. The part of the microscope that is closest to the specimen. Smallest distance between two points that can be seen as two points and not blurred into one point. QUICK CHECK 2 : Observing cells

11. The eyepiece lens and objective lens in a microscope have different magnifications. Together they magnify the object. Total magnification = eyepiece lens x objective lens magnification magnification Calculating Magnification ANSWER Total magnification = 10 x 50 = 500

12. PRACTICE QUESTIONS What is the total magnification of a microscope with an eyepiece magnification of x10 and an objective lens magnification of x30? Laila wants to observe an onion cell under the microscope. What is the total magnification if the eyepiece magnification of x40 and an objective lens magnification of x20? What is the total magnification of a microscope with an eyepiece magnification of x40 and an objective lens magnification of x30? Challenge : What is the objective lens magnification if the total magnification is: x200 and the eye piece is x5. Show your working out in your book! 300x 800x 1200x 40x

13. Eyepiece Magnification Objective Magnification Total Magnification 10x 4x 40x 10x 5x 5x 200x  120x 600x  5x 100x 10x   1250x QUICK CHECK 3: CALCULATING MAGNIFICATION   5x   40x   125x   500x   500x

14. SUMMARY QUESTIONS Copy and complete the sentences below. All living organisms are made up of ____________ - these are the ____________ blocks of life. To ____________ cells in detail you need to use a ___________. This ___________ the object. (5 marks) 2. Describe what the following parts of a microscope do: (3 marks) Lenses Stage Focusing knobs CHALLENGE: Describe in detail the method you would use to observe the cells within a white flower petal. Use the following key words: Microscope, magnification, resolution, eyepiece, objective lens, stage, slide, coarse focus, fine focus, light, observation.

15. Eyepiece Objective lens Stage Light Coarse/fine focus CLASS PRACTICAL : How to use a Microscope Follow the steps below to observe an object using a microscope. (1) Collect a light microscope (2) Take a slide from the box (3) Move the stage to its lowest position (4) Place the object you want to observe on the stage (5) Select the objective lens with the lowest magnification (6) Look through the eyepiece and turn the coarse-focus knob slowly until you see your object (7) Turn the fine-focus know until your object comes into focus (8) Repeat steps 6 to 7 using an objective lens with a higher magnification to see the object in greater detail. https://www.youtube.com/watch?v=xzjowD1KN20

16. EXTENSION : Making an onion skin slide 1. Watch the teacher demonstration 2. Make your own onion slide 3. Use the worksheet to help you if needed TASK: Sketch the onion cell that you see in the microscope. Can you label the parts that you can see?

17. Drawing Microscope Slides / Specimens: 1. Use a pencil 2. Draw only the lines you see. No shading or colouring 3. Each circular diagram ( field of view ) should be about a 3 rd of a page in size 4. If the cells you are viewing are similar/repetitive it’s useful to draw about 4-5 only Always record the : magnification name of specimen and the date of the observation

18. What is it? Onion Cells