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Cells - Paper 1 - Coggle Diagram
Cells - Paper 1
Specialised Cells
When a cell changes to become a specialised cell, it is called Differentiation
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Chromosomes and Mitosis
In the Nucleus of a human cell, there are 23 pairs of chromosomes.
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Stem Cells
Embryonic stem cells are undifferentiated cells, they have potential to turn into any kind of cell
Adult stem cells are found in the bone marrow, they can only turn into some types of cells eg. blood cells
Uses of stem cells :
- Replacing faulty blood cells;
- Making insulin producing cells
- Making nerve cells
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For stem cell research >
- Curing patients with stem cells - more important than the rights of embryos
- They are just using unwanted embryos from fertility clinics, which would normally be destroyed.
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Exchange - Humans
Multicellular organisms have a large area to volume ratio so that all the substances can be exchanged.
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Villi - Small Intestine
Millions of villi line the small intestine to increase the surface area to absorb more digested food.
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Exchange - Plants
The surface of the leaf is flattened to increase the surface area for more gas exchange by diffusion
Oxygen and water vapour diffuse out of the stomata. Guard cells open and close the stomata, controlling water loss.
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Key processes
Diffusion - is the spreading out of particles from an area of higher concentration to an area of lower concentration
Cell membranes - they're semi-permeable, only small molecules can get through
Osmosis - Is the movement of water molecules from an area of high concentration to an area of low concentration through a partially permeable membrane
Active transport - It is the movement of substances against the concentration gradient. This process requires energy from respiration.