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AS Biology Unit 1 Module 1 Revision Notes OCR

Spread 1 ­ Living organisms consist of cells

1. State the resolution and magnification that can be achieved by a light microscope.
Light microscopes have a number of different magnifications because it has many different object lenses which are responsible
for…

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Flagella (undulipodia) are hair like extensions which stick out from the surface and are made from 9 microtubules arranged in
a cylinder shape , an example is the tail of a sperm this helps the sperm move as it is used as a motor you will normally find 1 or…

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The protein is then packaged into a vesicle and then transported to the Golgi apparatus which modifies the protein and
packaged again so it can moved out the cell by exocytosis.



2. Comparing the structure of eukaryotes and prokaryotes.
Prokaryotic features ...
They are bacteria and are smaller than eukaryotic…

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Increasing temperature increases kinetic energy in the molecule, this also increases movement and makes the membranes
leaky which would allow substances which normally wouldn't enter, more cholesterol helps with cell stability so membranes
present in hotter environments have to adjust.

Spread 9 ­ Communication and cell signalling

1. Explain the…

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Example of active transport is calcium ions when a muscle is stimulated, there's a high concentration of calcium ions in the
endolplasmic reticulum, they are released by diffusion but when needed to be stored again protein calcium ion pumps are
used to restore the calcium ions.
Endocytosis is when materials…

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Prophase- Chromosomes are replicated in Interphase, then they super coil in prophase , the nuclear envelope breaks down
and centrioles divide into two and move to opposite poles of the cell and produce spindle fibres which will be used later in
metaphase
Metaphase ­ replicated chromosomes line up in the…

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Xylem and phloem are produced from divided meristem cells such as cambium; they undergo differentiation to form all the
different kinds of transport tissue
Xylem consists of xylem vessels with parenchyma cells and fibres, meristem cells produce small cells that elongate and become
water proof by lignin, this kills the…

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