Announcements
• Register clickers
• Experimental design problem due on
Wednesday
• Homework assignment 2 in
MasteringBiology due Friday, right before class • Pretest… Avg. 16.7/39
Outline
I. Wrap up discussion of experimental design (brief)
II.Introduction to Energy and Laws of
Thermodynamics
III.Apply understanding of energy and matter to ecosystems
I. Food chains and webs
II. Energy flow through ecosystems
Assembly question:
• What are the implications of energy transfer and nutrient cycling to populations, communities, and ecosystems? 1
1/12/2014
Big Ideas
• Applying concepts across different levels of biological organization
• Energy flows, matter cycles
• Heat accompanies transformations of energy • Energy and matter are conserved
Part I: Energy
• “It is important to realize that in physics today, we have no knowledge of what energy is”
Part I: Energy
• Capacity to do work or supply heat • Must be thought of in terms of a particular “system”
2
1/12/2014
Macroscopic Manifestations of
Energy
–Motion
–Light
–Sound
–Electrical
fields
–Magnetic fields
–Thermal energy
Thermal Energy
• Total kinetic energy caused by the vibration and movement of the atoms and molecules within substances.
• Low organization, hard to harness
• Not very useful for living systems,
“wasted energy.”
Energy at the Microscopic Scale
Can be modeled as
–The motion of particles
–Being stored in force fields • Electrical, magnetic, gravitational –Mediates interactions among particles
3
1/12/2014
Short hand: Forms of Energy
–Electrical
–Motion
–Light
–Thermal energy –Chemical
–Elastic
(spring)
–Nuclear
–Gravity
Forms is misleading: all are ultimately, at the atomic scale, some mixture of kinetic energy, stored energy, and radiation
Understanding Energy
• The first law of thermodynamics:
– Energy is conserved: it cannot be created or destroyed, but it can be transferred or transformed. What is happening in the system ????
Energy In
Energy Out
Transformations of energy
• Transformation 1:
– Plant growth
• Transformation 2:
– Light striking the retina
• Transformation 3:
– Compost pile
• Transformation 4:
– Bioluminescence
4
1/12/2014
Understanding Energy
• Second Law of thermodynamics:
– Entropy of an isolated system will tend to increase – Nature tends toward disorder
– Higher entropy means what??
Ecosystems
• A biological community plus all the abiotic factors that influence that community
– Ecologists study factors that influence the distribution and abundance of organisms.
– Ecosystem ecologists: primary production, energy flow, matter cycling
DOMAIN BACTERIA
Firmicutes
Spirochaetes
Actinobacteria
Chlamydiae
Cyanobacteria
-Proteobacteria
-Proteobacteria
-Proteobacteria
-Proteobacteria
This node represents the common ancestor of all organisms alive today
-Proteobacteria
DOMAIN ARCHAEA
Korarchaeota
Phylogenetic
Tree of Life
Aeropyrum
Sulfolobus
Thermoplasma
Archaeoglobus
This node represents the common ancestor of archaea and eukaryotes Pyrococcus
Methanococcus
DOMAIN EURKARYA
Diplomonads
Slime molds
Animals
Fungi
Red algae
Green algae
Land plants
Animals, fungi, and plants are small branch tips on the tree of life
Foraminifera
Oomycetes
Brown algae
Diatoms
Ciliates
Dinoflagellates
Apicomplexa
5
1/12/2014
Functional grouping of organisms
Primary producers: autotrophs that can synthesize their own food Decomposers: feed on dead organisms or their waste
Consumers: eat living organisms
Herbivores, carnivores, secondary carnivores, etc http://www.nytimes.com/2012/09/12/us/salton-sea-is-blamed-for-southern-california-stench.html?_r=1
The biotic components interact with abiotic components
Primary producers Abiotic environment Consumers
Decomposers
6
1/12/2014
Energy Flow in an Ecosystem:
Trophic Levels and Food Chains
Quaternary
consumers
• A food chain
– Is the sequence of food transfer from trophic level to trophic level – May have many levels – What do arrows represent??? Carnivore
