What happens during the double circulation of blood?
The blood passes through the heart twice, keeps the oxygen going to cells oxygenated.
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Adaptions of an artery
Outer layer holds the artery open, middle layer contains elastic tissue allowing the walls to be streched under high pressure and recoil. Inner endothelial layer is smooth for minimal resistance.
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Adaptions of veins
Large lumen to reduce resistace of low pressure blood and there are valves at intervals to stop back flow of blood.
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Adaptions of capillaries
Single layer of squamous epithelium cells, providing a short diffusion pathway.
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What is tissue fluid?
Fluid that bathes cells for exchange of substances. The fluid has been forced out of the capillary walls by the high hydrostatic pressure of the blood. It is formed at the aterial end of capillary.
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What is the lymphatic system?
Where the remainder of tissue fluid goes that is not reabsorbed back into the capillaries. It carries this back towards the heart to join the blood again.
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Why do plasma proteins stay in the blood vessels?
They are too big to pass into the tissue fluid. By staying in the blood plasma they reduce its water potential.
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How does waste material move from the tissue fluid back into the blood?
Diffusion and osmosis down the concentration gradient at the venus end of the capillary.
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How does water enter a plant?
By osmosis through the root hair cells which have a large surface area.
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Passage of water after the root hair cells
Root hair cells, cortex, endodermis, phloem then the xylem.
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What is the symplast pathway?
Water moves throught the cells in the plant.
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What is the apoplast pathway?
Water moves around the cells through intercelluar spaces, sometimes through the cell walls.
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What is a casparian *****?
A waxy ***** that block apoplast pathways so water has to take a symplast pathway.
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How does the xylem maintain a low water potential?
Cells surounding the xylem secrete ions into the xylem.
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How does root pressure work?
As more water enters the xylem it creates a pressure which pushes water up the plant. This pressure is weak and wouldnt be able to push water up a big plant.
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What is cohesion-tension?
As water evaporates it creates tension which pulls up water into the leaf. Water molecule are cohesive (stuck to eachother) so as one molecule is pulled up all molecule follow in a collum.
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4 factors which effect transpiration
Light , Temperatue, Humidity and Wind
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Other cards in this set
Card 2
Front
Adaptions of an artery
Back
Outer layer holds the artery open, middle layer contains elastic tissue allowing the walls to be streched under high pressure and recoil. Inner endothelial layer is smooth for minimal resistance.
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