Cells Cont’d
Animal & Plant Cell
Electron vs Light Microscope
Cont’d
What are the advantages of using an electron
microscope?
• 1) Very high magnification
• 2) Very high resolution
• 3) Can use living material
• 4) Natural color maintained
• A)2 only
• B)3 & 4
• C)1 & 2
• D)4 Only
Images of Plant & Animal Cells
Plant or Animal Cell?
Electron Micrograph
of Plant Cell
Plant or Animal Cell?
Organelles under Electron Microscope
Magnification vs Resolution
• Magnification – the degree to which an image is blown up or
magnified.
• Resolution – the degree of detail that can be seen in an image.
• Shorter wavelengths give the best resolution. Blue Light is the
shortest wavelength on electromagnetic wavelength, to get around
the limit of resolution in light microscopes, electron microscopes are
used.
Calculating Magnification
• Objects under a microscope are magnified
• Magnification is the size of an image divided by the
real size of the object
• Magnification (M) = Image Size (I) / Actual Size (A)
• Magnification is always written with X (times) in
front.
Question:
1. The diameter of a cell in a photograph is 6cm. The diameter of the actual cell is 30μm. The magnification of
the photograph is:
A. x 200
B. x 2000
C. x 180 000
D. x 1 800 000
cm- mm x 10
mm- micrometer x1000
A chloroplast in a hibiscus leaf measured 1μm. On the electron micrograph the
length of the organelle was 20mm. What is the magnification of the electron
micrograph
• 200 times
• 2000 times
• 20,000 times
• 200,000 times
Question 2
1. The diameter of a cell is 80μm. The magnification of the image is x 30. What is the diameter of the image
produced?
A. 2.4μm
B. 2400μm
C. 24μm
D. 24000μm
Example
Image = 30mm
Actual Spider = 10mm
Magnification = I/A
Cells in Dicotyledonous Roots
• Cells can be grouped together of the same function
• Tissues are a collection of cells which all serve the same function
• E.g parenchyma, xylem, phloem
• Organs are a collection of tissues
• E.g Plant Root
Root Hair: responsible for
absorption of water and
minerals
Cortex: made up pf
parenchyma tissue. Allow
water to move into xylem
Root Hair: responsible for
absorption of water and
minerals
Vascular tissues to the center:
responsible for absorption of
water and minerals known as
the stele
Endodermis: waterproofed
cells by the casparian strip
Pericycle: cells that go on to
form lateral roots
Xylem: contains dead empty
cells with lignified side walls.
Transports water, supports
the plant
Phloem: contains living cells
known as phloem sieve
elements. Phloem is
perforated to allow sucrose
solution to enter