Confusing Terminology
C4 photosynthesis
Photosynthesis
The conversion of light energy to the chemical
energy of organic molecules
High
concentration
of CO2
5 carbon
carb n sugar
su ar used tto capture CO2 in
photosynthesis
Ribulose bisphosphate
RUBP
https://www.msu.edu/~ngszelin
/RuBP2.JPG
The Enzyme used to link CO2
and RUBP
RuBP carboxylase
Rubisco
https://www.msu.edu/~ngsze
lin/calvin_cycle_players.htm
CAM (Crassulacean Acid Metabolism )
photosynthesis
C3 Vs. C4
Photosynthesis
C4 plants have better
‘water use efficiency’
Don t lose as much water
Don’t
Especially useful in arid environments
C4 plants do better when [CO2] is low
C4 plants pay extra energy costs (e.g., CO2
transport) for this
C4 plants are more common in warm and
dry environments
E.e., the tropics and subtropics
http://www.cartage.org.lb/en/themes/Sciences/BotanicalSciences/PlantHormones/Nutrition/Nutrition.htm
700
Water Loss
Types of Photosynthesis
grams wa ter lost per
ssue produced
gram plant tis
(From text pg 140)
600
500
http://manravbioeducation.b
C3- most common form of Photosynthesis
400
Does better than C3 & CAM when CO2 is abundant
C4 – Spatially separates Carbon capture and
Light capture
300
200
Better than C3 in hot, dry conditions
100
0
C3
C4
CAM
CAM- Temporally separates Carbon capture
and Light capture
Best in really dry conditions
1
Types of plants
in each category
Chemosynthesis vs.
photosynthesis
Echinacea purpurea ( Coneflower);
C3 pathway – most plants
Zea mays (Corn)
C4 pathway- many grasses
Opuntia humifosa
(Beavertail Cactus);
Solar energy is
the energy
source for most
food webs
CAM pathway succulents
http://www.swbic.org/education/webquests/photosynthmain.php
http://www.bigelow.org/foodweb/chain4.html
Detritivores
Functional Response
How are the three types different?
Why do they level off?
http://www.hiltonpond.org/ThisWeek040508.html
What is it that limits energy
consumption?
http://en.wikipedia.org/wiki/Saprotroph
http://i.pbase.com/o5/30/681730/1/68842751.kGAbQuPy.Kalkongamterpingvinung
http://web.utk.edu/~ctmelear/ossabaw/RobertoOwenAsh/mushroom.gif
Functional Response
Peanuts to harvest and shell
Handling time is shortsearching is the limiting
step
20 seconds
Density: 1/m2, 2, 5, 10, 100
Food intake/ 20 sec
c
Chemicals produced
by deep sea vents
(H2S) are the primary
energy source in a
few cases
Handling time is limiting
when food is abundant
g time
m and
Both handling
search time are both
limiting in between
Search time is limiting
when food is rare
1
2
5
Peanut Density
10
100
Prey can hide better when rare
Learning by predators
‘Switching’
6-18
The book
doesn’t
explain what
causes a
type III
response–
this was a new
omission in 4th
ed!
2
Factors that may limit the
performance of organismsConditions vs. Resources
Factors that may limit the
performance of organismsConditions vs. Resources
Condition: An abiotic
environmental factor which
varies in space and time and
affects the p
performance of
an organism
Resource: a factor of the
environment that becomes
unavailable to other
organisms when it is used
Consumed or used up so it is
not available to others
Performance usually increases
with abundance of a resource
up to some plateau
e.g., food, water, nesting
sites, hiding places, etc.
Not consumed or used up
Performance usually peaks at
an intermediate value of the
condition (an optimum)
e.g., temperature, relative
humidity, pH, salinity, stream
flow velocity, concentration
of pollutants…..
Chalk talk about limits
Self-Test
When is photosynthetic
rate of Adiantum decorum
limited by photon flux
density?
100
500
a)
Photon flux density
y < 100
b)
Photon flux density > 500
c)
Photon flux density > 1,250
d)
Photosynthetic rate is
limited by photon flux
density under all conditions
shown
Photosynthetic rate is not
limited by photon flux
density in these data
e)
µmol/m
l/ 2/sec
/
µmol/m2/sec
µmol/m2/sec
3