Physiology Quiz 2

what is turgor pressure responsible for?

cell expansion, mechnical support, opening of stomata, radicle emergence

what is thigmonasty and thermonasty?

thigmonasty: touch induced leaf movements

thermonasty: temp induce leaf curling/bending

what is water’s polarity?

neutral yet polar, asymmetric electron distribution makes water polar

what are important functions of water?

solvent, reactant (photosynthesis), provides hydration for enzymes, cell membranes

how does water interact with the cell membrane?

cell membranes need water for their structural stability and function

what is vital water?

the water that surround proteins providing it structural stability and ensuring it functions

what can removal of vital water cause?

injurious alteration to proteins/membranes (for instance, freeze-desiccation)

what is water’s high latent heat of vaporization? describe

energy needed to convert 1 g liquid water to 1 g vapor: 540 cal; high due to the strong H-bonds; causes a cooling effect when water evaporates

what are four examples of water’s latent heat of vaporization/evaporative cooling?

greenhouse cooling, cooling turf-grass in a golf course, delay bud-break in the spring, cooling of leaves (thru transpiration)

what is latent heat of fusion?

the amount of heat released when 1 g of liquid water is converted to 1 g of ice, 80 cal/g water, freezing of water has a warming effect

what is a practical application of the latent heat of fusion?

use of sprinklers for frost protection

what is water’s high specific heat and how does it impact the world?

energy needed to warm 1 g of water by 1˚ C=1 cal (very high), large bodies of water have moderating effects on temperature during seasonal cooling/warming cycles

what is water’s high thermal conductivity?

rapidly conducts heat away from the source, aka transports heat quickly

what is water’s trait of relatively low viscosity important?

keeps viscosity of water low which helps water movement within the plant

what are the differences/similarities between cohesion and adhesion?

cohesion is water molecules sticking together while adhesion is water sticking to something other than water ex. xylem vessels, both are important for water movement

what can high cohesive forces lead to?

high tensile strength of water, water column remains intact under extreme tension

what is water potential?

measures the capacity of water to do work

if there is an area of high WP and an area of low WP, how will water move?

moves from high WP to low WP; greater the difference between the areas, the faster the water moves

is water potential higher or lower in a hypertonic solution?

lower

why is wp lower in a hypertonic solution?

increasing solute concentration decreases mole fraction of water, mole fraction of water is proportional to its free energy

what is passive transport?

movement of water along a water potential gradient (downhill)

what is active transport?

movement against a water potential gradient (uphill)

what are the components of water potential?

solute (osmotic) potential and pressure potential

what is osmotic potential?

osmotic pressure with negative sign

what is pressure potential?

net water movement can be stopped or reversed if sufficient pressure is applied to equal or exceed the osmotic pressure

what is water potential of a turgid leaf and a wilted leaf?

turgid leaf>0, wilted leaf <0

what is osmotic adjustment?

certain plants are capable of maintaining turgor and turgor dependent processes despite unfavorable conditions by roots/leaves lowering their water potential by increasing the solute concentration in the roots/leaves

what are the advantages of seed priming?

higher germination percentage, faster germination, more uniform germination

what is seed osmopriming?

pre-sowing treatment of seeds with a solution for a certain time and then dried back down; completes phase 1 and 2, partial hydration

what are the three factors of osmo-conditioning?

concentration, soaking duration, and temperature

How does partial imbibition/seed priming lead to better yields?

due to partial imbibition, seeds have a head start, are brought to a similar stage of germination, primed seeds do better under adverse environments

what is a pressure bomb?

when a stem is cut, water moves away from the cut. if pressure is applied from outside, it should push water back to the cut surface; the magnitude of pressure required to move the water back at the cut surface should equal to the water potential but with a negative sign