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Matter, Energy, and Life

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Outline

• Elements of Life • Organic Compounds and Cells• Energy

Laws of Thermodynamics Photosynthesis / Respiration

• Ecosystems Food Chains Ecological Pyramids Material Cycles

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ELEMENTS OF LIFE

• 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

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Elements of Life• Atoms - Smallest particles exhibiting

characteristics of the element. Protons - Neutrons - Electrons Atomic Number: Number of protons Isotope - Forms of an element differing in

atomic mass. - Different number of neutrons.

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Chemical Bonds

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

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Common Molecules

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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

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pH Scale

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Organic Compounds

• Organic Compounds - Material making up biomolecules. Formed by rings and chains of carbon. Four major categories:

- Lipids- Carbohydrates- Proteins- Nucleic Acids

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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.

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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.

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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

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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.

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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.

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Electromagnetic Spectrum

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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.

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Photosynthesis

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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

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Energy Exchange in Ecosystems

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SPECIES TO ECOSYSTEMS

• Population - All members of a species living in a given area at the same time.

• Biological 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.

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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.

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Food Web

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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.

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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}

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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 rabbit

1 kg fox

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Energy Pyramid

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MATERIAL CYCLES

• Hydrologic Cycle Solar energy continually evaporates water

stored in the oceans and land, and distributes water vapor around the globe.

- Condenses over land surfaces, supporting all terrestrial systems.

Responsible for cell metabolism, nutrient flow in ecosystems, and global distribution of heat and energy.

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Hydrologic Cycle

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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)

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Carbon Cycle

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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.

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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.

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Nitrogen Cycle

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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.

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Phosphorus Cycle

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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.

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Sulfur Cycle

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Summary

• Elements of Life • Organic Compounds and Cells• Energy

Laws of Thermodynamics Photosynthesis / Respiration

• Ecosystems Food Chains Ecological Pyramids Material Cycles

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