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UNIT 1 Cells, exchange and transport
Module 1 Cells

Magnification = the degree to which the size of an image is larger than the object itself
Resolution = the degree to which it is possible to distinguish between two objects that are very
close together (more detail)

Robert Hooke >…

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network of fibres (protein)
actin filaments able to move against each other, move some organelles inside cells
microtubules (tubulin) move a microorganism through a liquid, waft a liquid past a cell,
microtubule motors move organelles and other cell contents along the fibres(e.g.
chromosomes during mitosis, vesicles from endoplasmic reticulum to…

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modifies proteins from ER, may add sugar molecules
packages modified proteins into vesicles to be transported
modified proteins may go to surface of cell

Mitochondria
spherical or sausageshaped
two membranes separated by fluidfilled space
inner membrane highly folded (cristae)
central part called matrix
where ATP (adenosine triphosphate) produced during respiration…

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8 moved to cell surface, secreted outside

Eukaryotes
have true nucleus

Prokaryotes
bacteria
smaller than eukaryotes
no membranebound organelles
surrounded by cell wall (made of peptidoglycan)
ribosomes are smaller
DNA in form of single loop, small loops of DNA plasmids
free DNA, in nucleoid area
ATP production in mesosomes (infolded…

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lipid based molecules > diffuse down concentration gradient
small molecules and water > pass through bilayer
large molecules (e.g. glucose) > carrier proteins
Ions (e.g. sodium ions) > channel proteins

Endo inwards
Exo outwards
Phago solid material
Pino liquid material

Bulk transport endocytosis and exocytosis (via vesicles)
e.g. hormones (insulin)…

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squamous epithelial tissue for blood vessels, thin smooth flat surface
cilia + goblet cells

upper epidermis is transparent, lets light through
spongy mesophyll layer has air spaces to allow circulation of gases

Module 2 Exchange and transport
Exchange surfaces
large surface area so more space folding walls and membranes
thin…

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atria thin, do not need to create much pressure, only have to push blood into ventricles
right ventricle have to create pressure, pump deoxygenated blood to lungs, close, have to
keep down to prevent capillaries in lungs bursting because alveoli walls are thin
left ventricle needs pressure to overcome resistance…

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arteries lumen small, wall thick and contains collagen
veins lumen large, thinner layers so can be flattened by action of surrounding skeletal muscle,
do not stretch and recoil, valves
capillaries single layer of flattened endothelial cells, lumen narrow so red blood cells squeezed

blood + tissue fluid + lymph
hydrostatic…

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hydrogen ions taken up by haemoglobin to form haemoglobinic acid (to stop red blood cell
becoming too acidic)

oxygen tension of respiring tissues lower than that in lungs because oxygen used in respiration

Bohr effect > because hydrogen ions taken up by haemoglobin, less space for oxygen so
oxyhaemoglobin releases…

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this ensures water + dissolved nitrate ions have to pass into cell cytoplasm

Water moves up stem:
1 root pressure > water moves into xylem through osmosis because minerals moved into
xylem
2 transpiration pull > water molecules attracted to each other through cohesion, column,
so transpiration stream
3 capillary…

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