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G1 the cell grows and organelles are copied.
S DNA is copied and checked for any mutations.
G2 the cell grows some more.
M Nuclear division (mitosis or meiosis).
Different types of microscopes can reach different magnifications, and show different type of
Transmission electron microscope:
500,000 and it can show a 2D image
Scanning electron Microscope:
100,000 and a 3D image.
Tissues and Organs:
Tissues: a collection of similar cells that work together o perform a specific function
Organs: a collection of different tssues that work together to perform a particular function
Organ System: a collecton of different organs that work together to performa an overall life function
e.g. reproductive system, the digestive system.
Transport Tissues in plants:
Plants need to move water and minerals from the soil through their roots and stems and up into their
leaves. They also need to be able to move the products of photosynthesis around the plant to be
used for growth or stored in other places for later use.
In a plant, meristems are points at which meristem cells are produced. These are the only
undifferentiated cells in a plant which can specialise into any other form of cell needed. Meristem
regions are at the apex of the root and in the Cambium.
Phloem tissue consists of sieve tubes and companion cells. The meristem tissue produces cells which
elongate and line up end-to-end to form a long tube. Their ends do not completely break down, but
form sieve plates between the cells. The plates allow the movement of materials up or down the
tubes. Next to each sieve tube is a companion cell. These are very metabolically active. They move
the products of photosynthesis up and down the plant.
Movement across the cell membrane:
Diffusion: the movement of substances from a high concentration to a low without using energy.
Osmosis: diffusion of water particles from a high to a low concentration without using energy.
Active Transport: movement of substances against the concentration gradient (from a high to a low
concentration) using energy from ATP.
Active transport: is faster and more efficient, ATP is use to change the shape of the channel protein
Facilitated diffusion: passive allows large molecules and ions through the membrane using channel
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Can hold four molecules of oxygen
Haemoglobin plus oxygen equals oxyhaemoglobin
Foetal haemoglobin has a higher affinity for oxygen because it reduces the partial pressure of
oxygen which causes adult haemoglobin to release haemoglobin and on an oxygen dissociation
graph it's on the left.
The Bohr Effect:
The curve is on the left of the adult curve.
Carriage of Carbon dioxide:
Carbon dioxide plus water equals carbonic acid.…read more