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Mass Transport - Coggle Diagram
Mass Transport
Haemoglobin
Structure
- Secondary - each polypeptide chain is coiled into a helix.
- Tertiary - folding to ensure precise shape for carrying oxygen.
- Primary - sequence of amino acids in four polypeptide chains, 2 alpha and 2 beta.
- Quaternary - four polypeptides joined to create almost spherical molecule, each associated with a haem group containing a Fe²+ ion.
Oxygen
- Four oxygen molecules can be carried by a single haemoglobin molecule.
- The binding of oxygen to haemoglobin is called associating.
- The release of oxygen is called dissociating.
- Certain substances, like carbon dioxide, will cause the chain to change shape.
- Different organisms have different haemoglobins, which have different affinities to oxygen.
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Blood Vessels
Arteries
- Arteries stretch as blood is forced through them and then return to their original shape.
- You can feel this as a pulse.
- The blood they hold is usually bright-red oxygenated blood.
- Blood in arteries is under pressure, so they're dangerous to cut as blood will spurt out every time the heart beats.
- Carry blood away from your heart to your organs.
Arterioles
- They carry blood from the arteries to capillaries.
- The muscle layer is thicker than arteries, which controls the flow of blood.
- These are smaller arteries.
- The elastic layer is thinner than in arteries, as blood pressure is lower.
Veins
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- Valves prevent backflow of blood as there is a low pressure.
- Blood is low in oxygen and therefore a deep purple-red colour.
- Blood is squeezed back towards the heart by the action of the skeletal muscles.
- Carry blood to your heart from your organs.
Capillaries
- They have very thin walls.
- Thin walls allow easy diffusion of substances between blood and cells.
- Form a huge network linking arteries and veins.
- Blood is carried around the body in four main types of blood vessels; arteries, arterioles, veins, and capillaries.
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Phloem
- Made of columns of living, elongated cells.
- Carries food produced by photosynthesis.
- Has small pores which allow food (mostly sugar) to move up and down the plant - translocation.
- Sieve tube elements are alive, but have no nucleus and few organelles, so are supported by companion cells (part of phloem).
- There is one companion cell for each sieve tube element, and they are connected by plasmodesmata.
- Companion cells carry out living functions that phloem cells cannot do e.g. providing energy for active transport of solutes.
Xylem
- Carries water and mineral ions.
- Continuous upward movement of water is called transpiration stream.
- Made of dead cells with no end cell wall separating them.
- Tubes of xylem are strengthened by lignin.
- Transports water up the plant from root to leaf.