1. Matter, Energy, and Life
Chapter 3

2. Outline:
Basic Definitions
Organic Compounds and Cells
Energy
Laws of Thermodynamics
Photosynthesis / Respiration
Ecosystems
Food Chains
Ecological Pyramids
Material Cycles

3. BASICS
Matter - Everything that has mass and takes up space.
Solid - Liquid - Gas
Elements - Substances that cannot be broken down into simpler forms by ordinary chemical reactions.
Periodic Table

4. Basics
Atoms - Smallest particles exhibiting characteristics of the element.
Protons - Neutrons - Electrons
Atomic Number: # Protons
Isotope - Forms of an element differing in atomic mass. (Different # of neutrons)

5. Basics
Molecule: Two or more atoms joined together.
Compound: Two or more different types of atoms joined together.
Chemical Bond - Forces (chemical energy) holding atoms together in molecules.
Covalent - Sharing of electrons
Ionic - Cations and Anions
Hydrogen - Unequal attraction of shared electrons: Water

6. Molecules and Compounds

7. Ions, Acids, and Bases
Ions - Atoms that contain more or fewer electrons than protons.
Acids - Substances that release Hydrogen ions.
Bases - Substances that readily bond with Hydrogen ions.
pH Scale: 0-14
< 7 Acidic
> 7 Basic

9. Organic Compounds
Organic Compounds - Material making up biomolecules. Formed by rings and chains of Carbon.
Four major categories:
Lipids
Carbohydrates
Proteins
Nucleic Acids

10. Cells
Cells - Minute compartments in a living organism which carry out process of life.
Surrounded by lipid membrane controlling flow of materials in and out of cell.
Interior sub-divided into organelles and sub-atomic particles.
Enzymes - Class of proteins - molecular catalysts regulating chemical reactions.
Metabolism - Multitude of enzymatic reactions performed by an organism.

11. ENERGY
Energy - Ability to do work.
Kinetic - Energy in moving objects.
Potential - Stored energy.
Chemical - Stored in food or fossil fuels.
Power - Rate of doing work.
Heat - Total kinetic energy in a substance not associated with bulk motion.
Temperature - Measure of speed of motion of atoms in a molecule.

12. Thermodynamics
Energy must be supplied from an external source to keep biological processes running.
Energy flows in a one-way path through living systems and into a temperature sink.
First Law of Thermodynamics - Energy is neither created nor destroyed.
Second Law of Thermodynamics - With each successive energy transfer, less energy is available to perform work.
Entropy

13. ENERGY FOR LIFE
Ultimately, most organisms depend on the sun for energy needed to carry out life processes.
Solar energy is essential for (2) reasons:
Warmth
Photosynthesis
Radiant energy transformed into useful, high-quality chemical energy in the bonds of organic molecules.

14. Energy For Life
Of all solar radiation reaching the earth’s surface, about 10% is Ultraviolet, 45% is Visible, and 45% is Infrared.
Most of energy is absorbed by land or water, or reflected back into space.
Only about 1-2% of the sunlight falling on plants is captured for photosynthesis.

15. Electromagnetic Spectrum

16. Photosynthesis
Occurs in membranous organelles of green plant cells called chloroplasts.
6H20+6CO2 + solar energy = C6H12O6+6O2
Water and carbon dioxide in the presence of sunlight yields glucose (sugar) and oxygen.
Glucose serves as primary fuel for all metabolic processes in plant cells.

17. Respiration
Photosynthesis captures energy, while cellular respiration releases energy.
Cellular respiration splits carbon and hydrogen atoms from the sugar molecule and recombine them with oxygen to re-create carbon dioxide and water.
C6H12O6 + 6O2 = 6H2O +6CO2 + energy

19. SPECIES TO ECOSYSTEMS
Population - All members of a species living in a given area at the same time.
Community - All of the populations of organisms living and interacting in a particular area.
Ecosystem - Biological community and its physical environment.
Somewhat user-defined
Open or closed boundaries

20. Food Chains
Photosynthesis is described as Primary Productivity because it is the basis for almost all other growth in an ecosystem.
Manufacture of biomass by organisms eating plants is termed Secondary Productivity.
Food Chain - Linked feeding series.
Food Web - Most consumers have multiple food sources.

22. Trophic Levels
Trophic Level - Expression of an organism’s feeding status in an ecosystem.
Producers (plants)
Consumers
Primary, Secondary, Tertiary
Most terrestrial food chains relatively short.
Aquatic food chains tend to be longer.

24. Trophic Levels
Organisms can also be identified by the type of food they consume:
Herbivores (Plants) {Deer}
Carnivores (Meat) {Wolves}
Omnivores (Plants/Meat) {Bears}
Scavengers (Carcasses) {Crows}
Detritivores (Debris) {Ants}
Decomposers (All) {Bacteria}

25. Ecological Pyramids
Due to Second Law of Thermodynamics, food chains often form an inverted pyramid.
Metabolism
Predator efficiency < 100%
10% Rule (Energy / Biomass)
100 kg clover
10 kg rabbits
1 kg foxes

26. MATERIAL CYCLES
Carbon Cycle
Begins with intake of CO2 during photosynthesis. Carbon atoms are incorporated into glucose and then:
Remain in plant material until death.
Eaten by predator
Respiration
Excretion
Incorporation
Death (Decomposers)

27. Carbon Cycle

28. Nitrogen Cycle
Plants uptake inorganic nitrogen from the environment and build protein molecules which are later eaten by consumers.
Nitrogen-fixing bacteria change nitrogen to a less mobile, more useful form by combining it with hydrogen to make ammonia - used to build amino acids.
Members of bean family (legumes) have nitrogen-fixing bacteria living in their root tissue.

29. Nitrogen Cycle
Nitrogen re-enters the environment:
Death of organisms
Excrement and urinary wastes
Nitrogen re-enters atmosphere when denitrifying bacteria break down nitrates into N2 and nitrous oxide (N2O)gases.
Humans have profoundly altered nitrogen cycle via use of synthetic fertilizers, nitrogen-fixing crops, and burning fossil fuels.

30. Nitrogen Cycle

31. Phosphorous Cycle
Phosphorous compounds are leached from rocks and minerals and usually transported in aqueous form.
Taken in and incorporated by producers.
Passed on to consumers.
Returned to environment by decomposition.

32. Phosphorous Cycle

33. Sulfur Cycle
Most sulfur tied up in underground rocks and minerals. Inorganic sulfur released into air by weathering and volcanic eruptions.
Cycle is complicated by large number of oxidation states the element can assume.
Human activities release large amounts of sulfur, primarily by burning fossil fuels.
Important determinant in rainfall acidity.

34. Summary:
Basic Definitions
Organic Compounds and Cells
Energy
Laws of Thermodynamics
Photosynthesis / Respiration
Ecosystems
Food Chains
Ecological Pyramids
Material Cycles