Lecture #3 Energy fluxes and bioenergetics

Question 1

Universal rules

Answer 1

• All rates / fluxes are similarly represented in a rough way
  Rate ~ ease of process * difference in free energy
  E.g. umol of something m^-2 of leaf area s^-1 allows comparison of processes

Question 2

Thermodynamics (Point 2)

Answer 2

Point 2: for a process to occur, it either needs to be spontaneous (increases randomness), or have energy added to the system

Question 3

Thermodynamics (Point 3)

Answer 3

Free energy depends upon:
- temperature
- pressure
-chemical concentration and nature
- electrical characteristics
-gravity
-reference state

Question 4

Important questions to ask yourself

Answer 4

• A cellular process which are important?: e.g ATP formation via electro chemical gradient
• Across a root membrane which are important for ion movement? Chemical nature and concentration and electrical
• For an organ-level process which are important? Gravity and temperature differences are probably not important
• For a redwood tree level process which processes are important? Gravity especially important

Question 5

Solar radiation

Answer 5

W m^-2 = J s^-1 m^-2 = J m^-2 s^-1
‘Wavelength 250nm - 2.5 um
Intensity full sunlight ~ 1000W m^-2

Question 6

Light

Answer 6

Lux(weighted according to human )
Wavelength: 380nm- 750nm
Intensity: full sunlight 100000 Lux

Question 7

Photosynthetically Active Radiation (PAR)

Answer 7

Y: Photosyntheic % use of photons:
X: Wavelength

Question 8

Photosynthetic Photon Flux (PPF)

Answer 8

Responsible for chlorophyll: extracts methanol

Question 9

Photosynthetic Photon Flux Density

Answer 9

Wavelength: 400nm - 700nm
Intensity: full sunlight 2000 umol m^-2s^-1

Question 10

Solar Radiation Spectrum

Answer 10

Yellow: Sunlight at top of the Atmosphere e
Black line: 5250 C Blackbody Spectrum
Radiation at Sea level: 1500-1750

Question 11

Best aritificial light source