Download Understand the principles of conservation of matter and energy and

Matter, Energy, and Life
Objectives
• Understand the principles of conservation of matter and energy and appreciate
how the laws of thermodynamics affect living systems
• Know the roles of photosynthesis and respiration
• Define species, populations, communities, and ecosystems and understand
their significance
Objectives
• Discuss food chains, food webs and trophic levels
• Understand the major components of water, carbon, nitrogen, sulfur and
phosphorus cycling
Why do energy and chemistry matter?
• “Every organism is a chemical factory that captures matter and energy from its
environment and transforms them into structures and processes that make life
possible.”
Elements of life
• Matter - Everything that has mass and takes up space
• Solid - Liquid - Gas
• Conservation of Matter - Matter is neither created nor destroyed; it is
recycled over and over
• Elements - Substances that cannot be broken down into simpler forms by
ordinary chemical reactions
Energy
• Energy - Ability to do work
• Kinetic - Energy in moving objects
• Potential - Stored energy
• Chemical - Stored in food or fossil fuels
Heat
• Heat - Energy that can be transferred between objects of different temperature
• Specific Heat - Amount of heat required to warm one gram one degree C
• Thermodynamics is the study of energy and energy transformations
Thermodynamics
• 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 increases
Energy
• Living organisms require a constant input of energy, since they are ordered
• Energy must be supplied from an external source to keep biological processes
running
Organic compounds
• Organic compounds
• Material making up biomolecules
• Formed by rings and chains of carbon
• Four major categories:
• Lipids
• Carbohydrates
• Proteins
• Nucleic Acids
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
• Enzymes - Class of proteins - molecular catalysts regulating chemical
reactions
• Metabolism - Multitude of enzymatic reactions performed by an organism
Chemical reactions
• Most chemical reactions require an initial input of energy, or energy of
activation, to get started
• Enzymes, rather than heat, are used in cells to catalyze chemical reactions
Acids and bases
• Acids are compounds that readily release hydrogen ions (H+) in water
• Bases are substances that readily take up hydrogen ions (H+) and release
hydroxide ions (OH-) in solution
• Strength measured by concentration of H+
• pH scale
• 0-14
pH Scale
Qualities of water
• Weight of living organisms 60-70% water
• Universal solvent
• Dissolved salt solutions conduct electricity
• Cohesive, producing capillary action
• Exist as liquid over a wide temperature range
• Expands when crystallizes
• High heat of vaporization
• High specific heat
Sunlight
• Sun is a fiery ball of exploding hydrogen gas
• Radiant energy classified by wavelengths
• Intense energy has short wavelengths
• Lower energy has longer wavelengths
Sunlight
• Solar energy that reaches the earth’s surface is in, or near, the visible light
wavelengths
• More than half of the incoming sunlight may be reflected or absorbed by
atmospheric clouds, dust, or gases
• Short wavelengths are filtered out by gases in the upper atmosphere
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
• Only about 1-2% of the sunlight falling on plants is captured for
photosynthesis
Photosynthesis
• Occurs in membranous organelles of green plant cells called chloroplasts
• 6H20+6CO2 + solar energy = C6H12O6+6O2
• In other words, 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
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 create carbon dioxide and
water
• Respiration occurs in the mitochondria
• C6H12O6 + 6O2 = 6H2O +6CO2 + energy
Energy
Energy for life
• Organisms that cannot photosynthesize must get respire to release energy by
consuming plants or animals that consume plants
• Primary producers are photosynthesizing organisms
• Consumers get their nutrients from eating other things
Species to ecosystems
• Species - “type” of organism, interbreeding
• 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
Species
Populations
Communities
Ecosystems
Food chains
• Productivity of an ecosystem is the amount of biomass (mass of biological
material) that is produced per unit area per unit time
• Food Chain - Linked feeding series
Food chain is a linked feeding series
Food chains
• Food chains are generally short in terrestrial systems and long in aquatic
systems
• Food chains are generally shorter in harsh conditions than in favorable
conditions
Food webs recognize that most consumers have multiple food sources
Trophic levels
• Trophic level - Expression of an organism’s feeding status in an ecosystem
• Producers (plants)
• Consumers
• Primary, Secondary, Tertiary
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}
Ecological pyramids
• Due to Second Law of Thermodynamics, food chains often form a pyramid
• Large amount of energy, numbers and biomass at bottom of the food chain
Energy pyramid
Biomass and numbers pyramid
Why is energy lost at each level?
• Digestion efficiency
• Metabolism
• Predator efficiency < 100%
• 10% Rule
• 100 kg clover
• 10 kg rabbit
• 1 kg fox
Material cycles
• Hydrologic Cycle
• Most water is stored in the oceans
• 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
Carbon cycle
• Carbon is a structural component of organic molecules and provides metabolic
energy
• 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
Carbon cycling
• Recycling times of Carbon vary
• Carbon sinks store carbon
Nitrogen
• Nitrogen is important in proteins
• Nitrogen gas makes up 78% of atmosphere
• Nitrogen gas has a triple bond and is very stable
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
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
• Causes algal blooms, weed invasions, loss of soil nutrients, etc.
Phosphorous cycle
• Phosphorus compounds carry biological energy
• 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
Sulfur cycle
• Sulfur is found in proteins
• 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 different states the element can
assume
• Human activities release large amounts of sulfur, primarily by burning fossil
fuels
• Important determinant in rainfall acidity