- smallest living organisms - single cells. can carry out all functions of life.
- specialised cells - carry about a particular job, have specific function and structure
- cell becomes specialised so its adapted to its job. look very different to typical plant/animal cell
- examples: sperm, eggs, red blood cells and nerve cells.
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- if you eat more food than need - body makes fat, stores it in fat cells
- helps us to survive when food - short supply
- three main adaptations: small amounts - cytoplasm. lots of fat
- few mitochondria - cell needs little energy
- expand - 1000 times its original size - (fills with fat)
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Cone Cells (human eye)
- light-sensitive layer of eye (retina) makes us see with colour
- three main adaptations: outer segment has special chemical - changes chemically in coloured light. needs energy to change it to its original form.
- middle segment packed with mitochondria. release the energy to reform visual pigment. lets us see continuously in colour.
- final part: specialised synapse connects optical nerve. when coloured light makes visual pigment change - impulse is triggered. impulse crosses synapse travels along optic nerve to brain.
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Root hair Cells
- find it near tips of growing roots.
- Plants have to take in - water (lots) and dissolved mineral ions
- root hair cells helps to take up water - efficiently
- always close to xylem tissue
- this carries water and dissolved ions to the rest of plant.
- two main adaptations: root hairs increase surface area for water to move in cell
- have large permanent vacuole speeds up movement by osmosis from soil across root hair cell
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- released far away from egg that fertisile. contains genetic information from male.
- need to move through water (animal) or female reproductive system to reach egg. have to break egg.
- four main adapataions: long tail whips side-to-side helps move sperm.
- middle section full of mitochondria - provides energy for tail
- acrosome stores digestive enzymes - breaks down outer layers of egg
- large nucleus has genetic information - passed on
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