Transcript 1 plant cell - Moodle Ecolint

Year 7 Science – 6th of March 2013 – Cell Unit. S. Rathier
Plant and animal cells I
Today’s objectives are:
• To practice the skills you have
learned last week
• To discover what animal and
plant cells look like under the
microscope and learn how we
can tell them apart
• To learn how to make biological
drawings
Starter – cell fact or fiction?
There are about 1 000 000 000 000
cells in your body
The heaviest known cell is the ostrich egg
There are more bacterial cells in your body than
human cells
Brain cells live longer than any other cell
Some cells eat other cells
The longest cell in your body is over a meter long
People and mushrooms have the same type of cells
Cells glow in the dark
Cells commit suicide
What are cells?
What are cells?
• Cells are the building blocks of life
• The cell is the smallest viable form of
life.
Using microscopes – quick
reminder
• Carry with both hands close to body
• Bring the stage up looking from the
side
• Start at low power (red lens)
Prepare your own animal and plant cell slides!
Watch this video closely: it’s all in there!
http://www.youtube.com/watch?v=GHnndVuaync
Biological drawings
Draw 1 onion cell and 1 cheek cell – they will be collected at the
end and you will need them next lesson, so do your best work!
Basic rules
1)
2)
3)
4)
5)
6)
Title
Title
Use whole page
Titles
Use pencil
Use solid lines
Don’t colour or shade
Give magnification
For example 10 ×10 = 100 or ×100 magnification’
Biological drawings
Criteria for a good drawing
Marks
Underlined title
1
Magnification calculated and shown
2
Drawing fills most of page
1
Sharp pencil used
1
Solid lines
1
Any shading is done with dots
1
Cell parts are labelled
2
Label lines are drawn with ruler
1
TOTAL
10
My score
Activity – plant and animal cells
1. Plant cell – DO THIS BEFORE YOU TRY THE CHEEK CELL
Drawing of a
plant cell
•
Work in pairs, prepare 1 slide for both
•
Person 1 get the microscope, the
marking scheme for drawings and
the blank paper (2 sheets per pair)
•
Person 2 get the onion, tweezers, 1
slide, 1 cover slip and dye (iodine)
•
Each student to draw 1 plant cell on
the upper half of the sheet of paper
2. Animal cell – LISTEN CAREFULLY TO SAFETY INSTRUCTIONS
•
•
•
•
•
Method
Scrape the cells out of your mouth with a cotton bud using your finger
to push against the cotton bud.
Put the cells on the slide by gently rubbing the cotton bud against the
slide ( Caution : Do not let the slide touch the desk as this will ruin your
results).
Add 1 DROP of Methylene Blue Stain to the slide (Do this over a sink as it
can get messy!).
Put a coverslip over the slide ( Caution : Be careful with the coverslip as
they are very delicate and break extremely easily).
Put the slide under the microscope.
Focus the microscope on the 10x objective, then the 20x and 40x
objectives.
• USE OWN COTTON SWAB ONLY ONCE
• DIPOSE OF AS INSTRUCTED IMMEDIATELY
Activity – plant and animal cells
2. Animal cell – LISTEN CAREFULLY TO SAFETY INSTRUCTIONS
•
Work in pairs, prepare 1 slide
each
•
Person 1 get 2 cotton swabs, 2
slides, 2 cover slips, dye
(methylene blue)
•
Person 2 get the blank paper (2
sheets per pair)
•
Each draw 1 cheek cell on the
lower half of the paper. You must
finish this work today so you may
not get to draw your own cell!
Diagram of an
animal cell
From what you have learned today….
Which of these are plant and which of these are animal cells?
• Use mini whiteboards
Extension work
The two types of cells (plant and animal) we
have been observing today have some
features in common. Which might these be?
What are some of the differences you have
noticed?
Definitions
• Cell membrane: contains the cell and controls what
passes in and out of the cell
• Nucleus: controls the cell and contains instructions to
make more cells
• Cytoplasm: where the chemical reactions take place to
keep the cell alive and working
• Cell wall: support the cell
• Vacuole containing cell sap (no chloroplasts in onion
cells)