Cells Lesson 4

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Cells Lesson 4
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How can we prove that cells exist if we cant see
them?
Use your scientific thinking
In your table groups you have got 2 minutes to
discuss your ideas and then we will talk about
them as a class
Make sure you listen to everyone in your group
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Learning intentions

• At the end of this lesson
• All will have
• used a microscope safely and effectively and
  produced a labelled diagram of an animal cell and
  a model aniaml cell.
• Most will have
• peer-assessed a labelled diagram of an animal
  cell and be able to recall the functions of parts
  of an animal cell,
• completed the crossword
• Some will have
• demonstrated their understanding by completing
  Microscopes, size and scale.

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Responsible use of microscopes

• Microscopes are fragile and delicate
• They should always be carried with two hands one
  underneath and one holding the curved part of the
  body.
• You should not touch the lenses.
• Persistent mistakes include
• holding the microscope with one hand
• focussing down onto the slide and breaking it
• turning the objective lens around and crashing
  into the slide
• forgetting to mop up excess liquid.

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How to use a microscope

• Now follow the instructions below carefully.
• Make sure you have selected the low power
  objective lens (its the smallest).
• Look down the eyepiece and adjust the mirror
  until it is as light as you can get it.
• Move the focussing knob until the objective lens
  is as far down as it will go.
• Put your slide on the stage and secure it with
  the stage clips.
• Using the focussing knob, move the objective lens
  slowly up. Until you can see something. (You
  will need to keep looking down the eyepiece as
  you do this).
• When you think you can see something, check with
  the teacher before drawing what you see.
• When you have finished, remember to remove the
  slide from the microscope before packing it away.

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How are we going to look at an animal cell?
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Remember the rules?
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Recording what you can see
Things outlined in black are probably air
bubbles! Get me to help you if you cant see!
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• Write a clear heading.
• Use a sharp HB pencil.
• Draw firm, continuous lines and avoid using too
  much shading.
• Include the magnification.
• Draw label lines with a ruler. These must not
  touch the structure they are labelling and should
  not cross each other.
• Write labels horizontally on the page (pupils
  often write along the same angle as the label
  lines) and arrange them neatly around (not over)
  the drawing.

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Recording what you can see
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What do all the parts do?
What do the organelles do?
Contain chlorophyll where photosynthesis happens
Controls what happens in the cell (contains DNA)

• Nucleus
• Cell membrane
• Cytoplasm
• Chloroplast
• Cell wall
• Vacuole

Contains cell sap keeps the cell firm
Jelly-like substance where reactions happen
Made of cellulose and supports the cell
Keeps substances in the cell and controls what
goes in and out
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Complete the activity

• Microscopes, size and scale.
• This activity will help develop your thinking
  skills.

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Objective lens
Nucleus
Eye piece
Coarse focus
Cell membrane
Light
Cytoplasm
Slide
Stage
Fine focus