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33 Cards in this Set
- Front
- Back
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Give two examples of things which need to be interchanged between an organism and its environment |
Respiratory gases Nutrients
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What happens to the surface area to volume ratio as an organism gets larger |
It decreases |
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Name Fiks Law |
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Why do organisms in cold places prefer a small surface area to volume ratio |
To reduce heat loss |
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What do insects do have reduce water loss |
Waterproof covering
Small surface area to volume ratio |
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What are the two ways respiratory gases move in and out the tracheal system? |
Along a diffusion gradient
Ventilation (movement of muscles) |
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Explain how spiracles limit water loss |
Gases enter and leaves through spiracles. When the spiracles are open, water can evaporate from the insect. So to limit water loss, insects must balance between opening and closing their spiracles |
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What is counter current flow? |
The flow of water is in the opposite direction to the blood flow. This results in there always being a concentration gradient |
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What is the structure of gills? |
Made up of gill filaments
At right angles to the filaments are the gill lamellae |
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How are leafs adapted for efficient diffusion? |
No living cell is far from external air Diffusion happens in air phase Thin, flat shape for increased surface area Many stomata
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How do plants limit water loss using stomata? |
They close to limit water loss, but have to balance between in taking air and limiting evaporation |
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What are the features of a transport system |
A medium to transport blood (blood plasma) A mechanism for moving the transport medium (heart) A means of controlling the flow of blood to suit changing needs in the organism |
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What is the artery and vein that is involved with the liver? |
Hepatic |
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What is the artery and vein that is involved with the Kidneys? |
Renal |
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What is the vein in between the stomach and the liver |
Hepatic portal vein |
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Name and describe the structure of blood vessels |
Arteries- Carry blood away from heart Arterioles- Smaller arteries that control blood flow from arteries to capillarys Capillaries- Tiny vessels that link artioles to vein Veins- Carry blood back to heart
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Name and describe the Structure of arteries, artioles and veins |
Tough outer layer- that resists pressure changes Muscle layer- Contract and control the flow of blood Elastic layer- helps maintain blood pressure Thin inner lining (endothelium)- smooth to prevent friction and thin diffusion |
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How is tissue fluid formed? |
blood flowing through capillarys causes a pressure called hydrostatic pressure. This forces tissue fluid out. |
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How does tissue fluid enter blood again? |
The hydrostatic pressure in cappilary is less than in tissue, so it is forced back in. Proteins in the blood lower water potential, so tissue fluid moves back into blood by osmosis |
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How are root hairs adapted? |
Long and thin, so they provide large surface area. Thin membrane for short diffusion pathway |
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How does roots take up water? |
Water potential of soil is higher than root, so osmosis occurs |
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Describe the apoplastic pathway? |
Water molecules are cohesive. As water moves along the cell walls it creates a tension that pulls the water. |
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Describe the symplastic pathway |
water potential of neighbour cell is less, so water moves by osmosis. Water moves through plasmodesma |
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Role of endothermal cells |
Use active transport to pump mineral ions into xylem This lowers water potential of xylem This creates a force called root pressure that pushes water up xylem |
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Describe transpiration |
Water evaporates Because of cohesion water molecules are brought upwards. This creates a continuous, unbroken pathway up the xylem, which is called the transpiration pull |
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Describe cohesion- tension theory |
Transpiration pull puts the xylem under a pressure called negative pressure
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How does light effect transpiration |
Photosynthesis only happens in light. So, at night the stomata closes, but in the day the stomata are mostly open, so more evaporation occurs |
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How does temperature effect transpiration |
Increase in temp. increases the kinetic energy of the water molecules, which increases rate of respiration Also, decreases water potential of air outside leaf, meaning larger conc. gradient |
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How does humidity effect transpiration |
Higher the humidity, the more water molecules outside leaf. This lowers conc. gradient. |
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How does air movement effect transpiration |
As water evaporates, it accumalates outside leaf. This reduces water potential, so less evaporation. Strong air movement however moves water vapour away from leaf, which increases conc. gradient |
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What is a xerophytic plant? |
A plant with extra adaptations to reduce water loss |
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Name and describe 3 adaptations of xerophytic plants |
Thick cuticle- the thicker the cuticle, the less the water loss Rolling up leaves- traps region of air, so no water potential gradient Hairy leaves- traps air to decrease water potential gradient |
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Name 2 more adaptations |
stomata in pits- traps air, decreases water potential gradient
Reduced surface area to volume ratio |
