lecture 09 - how do organisms acquire energy? autotrophs Flashcards
trophic/trophy/troph
having to do with food or nourishment
autotrophy
make their own complex carbohydrates for nourishment from inorganic C - sources
two types of autotrophy
photosynthesis and chemosynthesis
photosynthesis
energy from light (converts CO2 to complex sugars) derives energy from light
chemosynthesis
energy from oxidation (converts CO2 (or methane) to complex sugars) derives energy from oxidation
heterotrophy
use organic sources of carbon synthesized by others to derive energy (don’t produce their own and consume other organisms)
light
electromagnetic radiation (RA)
wave-particle duality
radiation behaves as a wave and particle (photon)
electromagnetic radiation
described as wavelengths and photon energy (amount of photons traveling in that wave)
PAR
photosynthetically active radiation
quantity and quality of light influences photosynthetic rates
what are the influences of photosynthetic rates
latitude (angle of solar radiation)
clouds (cloud cover)
landscape features
what percentage of PAR is absorbed by taller plants (canopy)
79%
what percentage of PAR is absorbed by the middle layer of plants
7%
what percentage of PAR reaches the forest floor (low vegetation)
2%
what percentage does the boreal forest reflect incoming PAR
10%
what adaptation do low vegetation plants have to make up for the lack of PAR they receive
use portions of wavelengths not absorbed by the canopy trees
what wavelength penetrates the water column the deepest
blue wavelength
what wavelength is absorbed by the autotrophs near the surface
red wavelength
what colour does the autotrophs at the surface reflect after receiving lots of the red light
reflect green
what colour does the autotrophs at the deep layers reflect after receiving lots of blue light
reflect red
PPFD
photosynthetic photon flux density
NPR
net photosynthetic rate
Pmax
max net photosynthesis
max net photosynthesis
a limit to photosynthesis that plants can reach
Isat
irradiance at saturation
the plant doesn’t have time to process any more energy intake
LCP
light compensation point
less PPFD with less photosynthetic rate
light intensity at which photosynthesis = cellular respiration
sun plant
achieve higher Pmax but are inefficient in using low PPFD
shade plant
achieve only small Pmax but more efficient at using low PPFD
low Isat = can be damaged in sunny sites
C3 photosynthesis
no separation of processes, very high photosynthetic rate, massive water loss
C4 photosynthesis
anatomic separation of processes, moderate water loss, energetically costly net benefit only in high temps
CAM
time separation of processes, negligible water loss, large reduction in photosynthetic rate
