Lecture 14: Chapter 8- Plant adaptations to the environment Flashcards
Transpiration
-water vaporization
-controlled by concentration gradient and how open stoma get
Plant water potential
-water always flows from high to low water potential
-think about the tree diagram: soil have higher water potential than the air so that is why it evaporates out
turgor pressure (hydrostatic pressure)
-keeps plants plump
-force exerted outward on a cell wall by the water inside the cell
-may be positive or negative
-a decrease in turgor pressure due to water loss decreases water potential
matric potential
-always negative
-large molecules, such as those in the cell water, and the cell walls exert an attractive force on water
osmotic potential
-always negative
-difference in solute concentration inside and outside of the cell causes water movement via osmosis
water use efficiency
water use efficiency (WUE) = mmoles of CO2 fixed / moles of H2O lost
typical range: 0.9-1.5 mmol/mol
sketch how C3 photosynthesis and respiration respond to temperature
they both increase w temperature, until they decline
explain how photosynthesis and the shape of leaves affect leaf temperature
-transpiration and convection cools leaves
-the bigger the leaf is the bigger the boundary layer is
-smaller leaves, deeply lobed leaves, and compound leaves have smaller boundary
*smaller and deeply lobed will be cooler
describe and compare the C3, C4, and CAM photosynthetic pathways
-C4: takes place during daylight hours. divided between mesophyll and bundle sheath cells. pre concentrates and prevents back-diffusion of CO2 CO2 reacts with PEP producing a 4 carbon molecule that is rapidly converted into a 4 carbon acid. organic acids are transported to bundle sheath cells where calvin cycle occurs
-CAM: photosynthesis reactions are divided between night and day. in the night it functions like a C4 plant. during day the stoma closes and calvin cycle occurs
both C4 and CAM divide photosynthesis
C4 divides between structures
CAM divides between day and night
list examples of C3, C4, and CAM plants and discuss their geographic distribution
C4-saline and arid areas WARM climates (celery)
CAM-desert (cactus)
explain how C3, C4, and CAM photosynthesis on the leaf level respond to the availability of light and CO2
C3- photosynthesis increases with amount of light and tapers off
C4- photosynthesis will increase as amount of light increase (straight line diagonal up)
for carbon refer to picture
both increase then level off but C3 requires more carbon
explain the term CO2 fertilization, how it has been studied, and discuss the impact of this phenomenon on the global C cycle and climate today and in the future
growing C3 and C4 plants in a number of different concentrations of CO2
C4 grow to same size regardless of concentration, but C3 plants will show effect on growth/size
-Land ecosystems (C3 plants) have taken up extra CO2, slowing the rise of atmospheric CO2 and climate warming
-As atmospheric CO2 continues to rise, the impact of CO2 fertilization will diminish
describe the traits of plants adapted to sub-optimal conditions (soil moisture, shade, cold temperatures, nutrient supply)
-in more arid environments, plants allocate more carbon to roots. decrease in leaf size.
-adapt to shade: lower root to shoot ratio (greater allocation to leaves)
-cold temp: optimal conditions adapts to temp. shape or having hairs on the leaves
-nutrients: low nutrient absorption rate. higher root to shoot ratio. increases leaf lifespan.
xylem
conducts water and dissolved nutrients upward from roots to leaves
phloem
conducts sugars and other metabolic products downward from the leaves
