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Comparitive Physiology


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What are the materials that are cotransported in plant cells?
proteins, H+, anions, sucrose
How are water and minerals transported from the roots to the leaves?
Transpiration, cohesion, and tension. Transpiration in the leaves pulls the cohesive chain of water up the xylem. the tree under tension.
How are sugars and a.a. transported from leaves to roots?
Bulk Flow/ Sink Model -- H+ pumped out of companion cells and sucrose and hydrogen move in by cotransport. builds pressure in companion cell. pressure pushed sucrose and hydrogen into sieve cell which moves down sieve tube to sink cell. From sink, moves into companions where it is diffused into surrounding cells. Source --> Sink
What is water potential?
the relative tendency for water to move away from a location. Water moves from high W.P. to low W.P.
what is plasmolysis?
water leaves cell and plasma membrans shrinks
When is a cell turgid?
when water enters a cell and the cell swells.
What connects the xylem tissues in plants?
plasodesmata(space) and vessel elements(tube)
What is the difference between symplast and apoplasts?
-symplast - same cytoplasm shared by cells
-apoplasts- runs in between cells and the casparian strip in the endodermis stops the water flow
Root Pressure Theory
ions pumped in, water flows osmotically, and the pressure pushes the water up the tree. only works in small plants (guttation)
Capillarity Theory
small tubes are better, doesn't work over long distances
Transpiration, Cohesion, and Tension Model
transpiration pulls chain up(H+ bonding of water). Trees are under tension.
What happens to gaurd cells?
Gaurd cells control the opening nad closing of stomata. When they becomine turgid, they swell and open the stomata-> K+ and water pumped into cell. Flaccid = closed stomata.
What are lamellae?
Flaps on fish gills where action is.
Countercurrent Gas Exchange
good diffusion all along lamellae. PO2 of blood leaving system can be greater than PO2 of water leaving the system. --> more efficient.
Concurrent Gas Exchange -- what would happen if water and blood flowed in the same direction?
PO2 in blood could never be greater than the PO2 of water. There would be wasted morphology.
Bird lung -- crosscurrent
air sacs change volume, air flow is unidirectional for inhalation and exhalation. 2 inhales and 2 exhales for one cycle. PO2 of blood leaving is higher than PO2 of air. no wasted morphology.
How would you prove that a bird has a crosscurrent vs. countercurrent?
REVERSE BLOOD FLOW --> if blood flow reversed, countercurrent would become concurrent and efficiency would decrease. reversing blood flow of crosscurrent would not decrease efficiency.
A swim bladder has a gas gland and rete mirabile (blood vessels) uses rete mirabile to maintain bouyancy.
How to keep gas in the swimbladder?
Countercurrent gas trap -- blood vessels are curved so O2 diffuses back across blood vessel and gets trapped until the PO2 in the blood vessel is eqaul to the PO2 in the swim bladder.
How can a fish add gas to its swimbladder?
Countercurrent Gas Trap/ root effect --> Lactic Acid in the gas gland causes hemoglobin to dump O2 at the blood vessel tip..continues till pressure is greater than 100atm. then O2 diffuses into swim bladder.

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