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5 Cards in this Set
- Front
- Back
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being multicellular enables cells to become specialised since it is not necessary for only one cell to carry out all the activities to sustain life. |
If the surface area to volume ratio was small then this mean that the cell used substances more quickly than it could obtain them so cellular activities would slow down or stop. |
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as organisms get larger the surface area to volume ration decreases. so that is why larger organisms tend to be multicellular because having many cells increase the surface area to volume ratio than a single cell. |
single celled organisms can satisfy its needs through simple diffusion because they have large surface area to volume ratio. and do not require large quantities of products because their volume is quite small.
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phospholipids allow the passage of certain lipid soluble substances through the membrane. |
cell surface membranes ( the membrane separating the cell from its external environment) needs to be: strong to offer mechanical support flexible to allow cells to move, grow and divide. self sealing so that the cell can divide without bursting |
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Cell surface membrane:
controls the passage if materials in and out of cells
recognition of other cells
receptor sites for hormones and neurotransmitters |
hormones that attach onto cell surface membraned tend to be small hydrophillic molecules.
the formation of a hormone receptor complex activates a glycoprotein in the membrane setting up a cascade of events or a direct response. |
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the hormones and the receptor sites on the glycoprotein on the cell surface membrane have complementary shapes. |
Done :D |
