Headstart Year 8 Science 2019 Name________________________________

By the end of this course you will understand:

1. all living things are made of cells (the tiny building blocks of life) 2. how to use a microscope accurately3. the differences between

multicellular/ unicellular plant/animal cells

4. the main components of the cell

1. What do you already know about cells?

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2. What are the characteristics of all living things?

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3. What is inside a cell?

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4. How do plant and animal cells differ? How are they alike?

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5. a) Where is the genetic information located in a cell? _____________________________________

b) Why is this important for cells? _____________________________________________________

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Cells

Before you begin

When you see me – you need to

record your answers…

6. What would happen if one of the parts of a cell was not working?

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Introduction

Cells are the basic units of all living things. The first cell appeared on Earth about 3.5 billion years ago. Today, there are many different kinds of cells. The differences in the cells of organisms are sometimes used to classify them into groups. Although cells may vary in their size, shape, contents and organisation, they all perform functions that are involved in keeping the organism to which they belong alive.

As you watch the videos ‘The wacky history of cell theory’ https://www.youtube.com/watch?v=4OpBylwH9DU and ‘Introduction to cells: The grand tour’

https://www.youtube.com/watch?v=8IlzKri08kk list as many facts about cells as you can in the box below.

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Video Task

You need to learn the parts of the microscope and how they help focus on an image. Use the diagram below and

animations from your teacher

1. Label the microscope parts (the links below will help you to do this).2. Listen to the animation (you will need Adobe flashplayer)

(http://www.cengage.com/biology/discipline_content/animations/light_micro.html ) – write how the parts mentioned help focus on an image.

3. Compare the field of view under x10 and x40 in the virtual lab, by completing the activity under ‘microscope measurement’ (http://virtualurchin.stanford.edu/microscope.htm )

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Meet the microscope

Quick review

(Circle the correct word/number in bold) When using a light microscope and moving from the x10 objective lens to the x40 objective lens you increase/decrease the field of view, and consequently the image will appear bigger/smaller. You will need to increase/decrease the light to focus the image under high power.

1mm = 1000/100 micrometres.

Equipment: 1 cm square piece of newsprint containing the letter ‘e’ , monocular light microscope, microscope slide, clear sticky tape

Important points to remember when using a microscope

1. When lifting the microscope, put one hand on the body of the microscope and one hand under its base.

2. The microscope should be used on a flat surface and not too close to the edge.

3. Take care that the light intensity is not too high, or it might damage your eye.

4. When you have finished using the microscope, return the shortest objective lens into position.

5. Remove the slide, and ensure that the stage is clean.

6. Make sure that, when your microscope is not in use, it is always clean and carefully put away.

Using a microscope

How to focus your microscope — and how not to!

1. Adjust your mirror so the appropriate amount of light passes through the hole in the stage.

2. Place the glass microscope slide (with a single hair specimen on top) onto the stage.

3. While watching from the side, use the coarse focus knob to lower the objective lens until it is just above the slide. Moving it down too far may shatter the slide.

4. While looking through the eyepiece lens, carefully turn the coarse focus knob until the specimen is seen clearly.

5. Carefully use the fine focus knob so that you can see the details of your specimen as clearly as possible.

6. Sketch what you see.

7. Suggest by how many times your specimen has been magnified

Method: Part 1

1. Carefully stick the 1 cm square of newsprint onto a clean microscope slide using sticky tape.

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Microscope

Prac 1

2. Using the microscope directions, get the paper into focus using the coarse focus knob and the lowest power objective lens (smallest magnification).

3. Carefully move the slide until you have a letter ‘e’ in focus.4. Change to a higher level of magnification by rotating to a higher power objective lens.

Answers these questions in the spaces provided:

1. In which direction did the paper under the microscope move when you moved the slidea. towards you orb. to the left?

2. What does the letter ‘e’ look like under the microscope? Draw a pencil sketch of what you see.

3. Record the magnification that you are using, and estimate how much of the viewed area is covered by the letter ‘e’ at this magnification.

Method: Part 2

In this activity, you will observe a Paramecium as an example of a protist. Your teacher will supply you with a hay infusion.

1. Take a drop of the solution and place it on a clean cavity slide, place a cover slip on carefully.2. Observe your sample under your microscope. Hopefully you will find paramecium swimming.

Follow a paramecium as it swims. You may have to switch to low power for this.Do you see anything that indicates that the Paramecium has an anterior end? Explain

On the following diagram add arrows to show the pattern of movement that you observed as a Paramecium swam. Did they swim in a straight line, or flip or…?

What happens when a Paramecium meets an obstacle?

Include a diagram (in the box provided)

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Using the diagram above:

Which structure do you think helps them move? Explain

Which structure do you think helps them feed? Explain

After reading the above “microscope use” steps – circle true or false for the following

1. Always carry a microscope with one hand TRUE /FALSE2. Always put the cover back on when finished using the microscope TRUE /FALSE3. Always use pen when drawing microscope images TRUE /FALSE4. Always add a stain to a microscope specimen TRUE /FALSE5. Always start on high power when locating a specimen TRUE /FALSE6. Always adjust the light to get the clearest view of the specimen TRUE /FALSE7. Always add a title to a microscope drawing TRUE /FALSE8. Always add a magnification to the microscope drawing TRUE /FALSE9. Always leave the slide on the stage for the next class when completing microscope lessons TRUE /FALSE10. Always listen to your teacher when they explain how to prepare a specimen on a slide TRUE /FALSE

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Read the information about plant and animal cells and list all the scientific terms

Quick review

Cells are the building blocks that make up all living things. Organisms may be made up of one cell (unicellular) or many cells (multicellular). These cells contain small structures called organelles that have particular jobs within the cell and function together to keep the organism alive. Cells can be divided on the basis of the presence and absence of particular organelles and other structural differences. Organisms can be classified by the different types of cells they are made up of.

Using the diagrams below answer the following questions:

Q: Are plants and humans multicellular or unicellular organism? ___________________________________________

Q: Which of the following cells is bigger? _____________________________________________________________

Q; What other differences do you notice about these cells?

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Watch “A world on unicellular organism” http://www.youtube.com/watch?v=gd3UOqxabuk&list=PL67D59E476FEBAC62&index=7 and then read the following information:

Protozoa is a subkingdom of unicellular, mostly aerobic, eukaryotic organisms. They are neither plants nor animals. They make up the largest group of organisms in the world in terms of numbers and biomass. Some protozoans, like Euglena, have chloroplasts like plants and make their own food in the process of photosynthesis, which makes them autotrophs. Others, like amoeba, are heterotrophs, feeding on bacteria, algae or other protozoans. Some protozoans can switch between being autotrophic and heterotrophic depending on the food sources available. Protozoans can be free-living or parasitic, unicellular or colonial. Some parasitic protozoans can cause diseases in humans. Protozoans move around using their flagella or pseudopodia - cytoplasmic temporary 'feet'. A paramecium is a small one celled (unicellular) living organism that can move, digest food, and reproduce. They belong to the kingdom of

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Multicellular/

Unicellular

Protista, which is a group (family) of similar living micro-organisms... They are about .02 inches long (.5mm). They are also famous for their predator-prey relationship with Didinium.

Label 1-6 as your teacher explains the main components of these cells.

Labels: Cell wall, cell membrane, nucleus, mitochondria, chloroplast, vacuoles and cytoplasm.

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Read the information about protozoans & Protista - list all the scientific terms

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In this activity, you will observe Elodea as an example of a plant. Your teacher will supply you with some pond weed. Take one leaf and place it on a clean slide with a drop of water, add a cover slip. Q: This is a living specimen; can you see evidence of this?

Before you start: Questions – answers can be recorded in space available at the end of this booklet.

1. What is the function of chloroplasts?

2. Name two structures found in plant cells but not animal cells.

3. Name three structures found in plant cells AND in animal cells.

4. What structure surrounds the cell membrane (in plants) and gives the cell support.

In the box below draw what you see, include a title, the magnification and labels of the features you can identify.

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Observing Elodea

Prac

Please ensure you follow all safety steps outlined by your teacher

1. Put a drop of methylene blue on the slide. 2. Gently scrape the inside of your cheek with a paddle pop stick. Scrape lightly.3. Stir the end of the toothpick into the stain to create a smear. 4. Place a coverslip onto the slide. Try to let it fall over the drop so that very few air bubbles form on the slide.

5. Use the SCANNING objective to focus. You probably will not see the cells at this power, but you should see the blue stain and perhaps some air bubbles. 6. Switch to low power. Cells should be visible, but they will be small and look like nearly clear purplish blobs. If you are looking at something dark purple, it is probably not a cell7. Once you think you have located a cell, switch to high power and refocus

In the box below draw what you see, include a title, the magnification and labels of the features you can identify.

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Observing Cheek cells Prac

Using the websites below as a guide, you are now going to draw and label your own plant and animal cells. You need to label the following features (cell wall, cell membrane, nucleus, mitochondria, vacuole, chloroplast, and cytoplasm). Draw them in the space below.

https://www.gtac.edu.au/teacher/teaching-resources/cells-online/ and https://www.cellsalive.com/cells/cell_model.htm

12Thinking

back

1. Name two things found in a plant cell that are not found in an animal cell:

2. How does the shape of a plant cell differ from that of an animal cell?

3. What is the function of the chloroplasts?

4. What is the function of the vacuole?

5. What is the jelly like substance found inside a cell? A. Cytoplasm

B. Chloroplast

C. Nucleus D. Cell membrane

6. What cells does a plant cell have but an animal cell does not?

A. Nucleus and cell membrane

B. Cell wall and cytoplasm

C. Cell wall and chloroplast

D. Cell wall and nucleus

7. The ___________________ controls all the activities in the cell.

8. Which of the following organisms reproduce by budding?

A. Yeast B. Amoeba

C. Paramecium D. Bacterium

9. A plant cell can make its food because it has _____.

A. Cytoplasm

B. A cell membrane C Chloroplasts

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Quick Review

. D. A cell wall

10. The part of a plant cell that gives it a regular shape is the _____.

A. Cell membrane

B. Chloroplasts C. Cell wall D. Cytoplasm

11. When one cell divides into new cells to reproduce. This process is called _____.

A. Cell production B. Cell division

C. Cell addition D. Cell subtraction

12. Which of the following(s) is/are made up of only one cell?

A. Yeast B. Bacterium C. Paramecium D. All of the above

13. What type of instrument is used to look at cells?

A. Microscope B. Binoculars C. Telescope D. Glasses

After completing this booklet on Cells I have learnt…..

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Summing up

Next year in Science I hope we learn more about……

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