Unit A: Biosphere Energy and Matter Exchange
I. The Biosphere and Systems
● The Biosphere: Often called the "living globe," it is the system of water
(hydrosphere), land (lithosphere), and air (atmosphere) that contains all living
and non-living things.
● System Types:
○ Open System: Exchanges both matter and energy with its surroundings.
○ Closed System: Exchanges energy but not matter. Earth is considered a
closed system because matter is constant while energy flows through it.
○ Isolated System: Exchanges neither matter nor energy.
● Dynamic Equilibrium: A state of balance where systems constantly adjust to
changes to maintain stability within the closed system of Earth.
● Gaia Hypothesis: Proposed by J.E. Lovelock. It suggests Earth functions like a
single living body where the biotic community is interconnected with the abiotic
environment.
II. Solar Radiation and Albedo
● Energy Source: The Sun is the primary energy source for the biosphere.
● Electromagnetic Radiation (EMR): Energy travels as waves; shorter
wavelengths carry more energy (e.g., UV) and can damage living matter, while
longer wavelengths (e.g., infrared) carry less.
● Albedo: The extent to which an object reflects light.
○ High Albedo: Light-colored surfaces (like polar ice caps) reflect more
energy and absorb less.
○ Low Albedo: Dark colors (like open water or forests) absorb more energy
and reflect less.
● Atmospheric Control: The atmosphere (troposphere, stratosphere with its
ozone layer) filters incoming energy, reflecting some and absorbing others before
it reaches the surface.
III. Energy Transfer and Trophic Levels
● Photosynthesis (PS): Plants convert solar energy into chemical energy
(glucose).
○ Equation: 6𝐶𝑂2 + 6𝐻2𝑂 + 𝑒𝑛𝑒𝑟𝑔𝑦 → 𝐶6𝐻12𝑂6 + 6𝑂2
● Cellular Respiration (CR): Organelles (mitochondria) in both plants and animals
convert glucose into usable energy (ATP) and heat.
○ Equation: 𝐶6𝐻1206 + 6𝑂2 → 6𝐶𝑂2 + 6𝐻2𝑂 + 𝑒𝑛𝑒𝑟𝑔𝑦
, ● Chemosynthesis: Occurs in deep-sea vents or caves where bacteria produce
organic compounds without sunlight using inorganic chemicals like 𝐻2 or 𝑁𝐻3.
● Thermodynamics:
○ First Law: Energy is neither created nor destroyed, only converted.
○ Second Law: Energy conversions are never 100% efficient; some energy
is always lost as heat.
● Trophic Levels: Categorization based on energy gain:
○ Producers (Autotrophs): First level; make their own food.
○ Consumers (Heterotrophs): Feed on others (Primary = herbivores,
Secondary/Tertiary = carnivores/omnivores).
○ 10% Rule: Only about 10% of energy is transferred from one trophic level
to the next; the rest is lost through waste, digestion, and heat from
respiration.
● Ecological Pyramids: Models representing relationships between levels:
○ Pyramid of Numbers: Based on the quantity of organisms.
○ Pyramid of Biomass: Based on the total dry mass of living material.
○ Pyramid of Energy: Always upright because energy is lost at each level.
IV. Matter Cycling (Biogeochemical Cycles)
Matter must cycle because there is no external source for it, unlike energy.
● Hydrologic Cycle: Moves water through evaporation, transpiration (release from
plants), condensation, and precipitation.
○ Leaching: Minerals are dissolved and carried away by water moving
through soil.
● Carbon and Oxygen Cycles: These are tightly linked through PS and CR.
Carbon is stored in the atmosphere (𝐶𝑂2), oceans, and the Earth's crust
(limestone, fossil fuels).
● Nitrogen Cycle:
○ Nitrogen Fixation: Bacteria or lightning convert atmospheric 𝑁2 into
nitrates (𝑁𝑂3) that plants can use.
○ Denitrification: Anaerobic bacteria convert nitrates back into 𝑁2 gas.
● Phosphorus Cycle: Cycles between rocks (long-term geochemical phase) and
living organisms (short-term biological phase) through weathering and
decomposition.
V. Biosphere Interactions and Human Impact
● Levels of Organization: Biosphere → Biome → Ecosystem → Community →
Population → Species.
, ● Niche vs. Habitat: A habitat is the physical "address" of an organism, while a
niche is its functional "role" or "job".
● Indicator Species: Sensitive organisms, like frogs, that provide early warning
signs of ecosystem stress.
● Species at Risk:
○ Special Concern: Low numbers at the edges of its range.
○ Threatened: Likely to become endangered if factors aren't reversed.
○ Endangered: Close to extinction.
○ Extirpated: No longer exists in a specific area but found elsewhere.
● Human Disturbances:
○ Biomagnification: The buildup of toxins (like DDT) in higher trophic
levels.
○ Eutrophication: Excess nutrients (fertilizers) in water cause algae
blooms, which deplete oxygen and kill aquatic life.
○ Monoculture: Growing only one crop reduces biodiversity and depletes
soil nutrients.
Unit B: Ecosystems and Population Change
I. Ecosystem Dynamics & Interactions
● Definition of Ecosystem: An ecological region where communities of plants,
animals, and microbes interact with their abiotic environment.
● Ecotone: A transitional area between two different ecosystems.
○ Characteristics: Often contains higher biodiversity than the individual
ecosystems because species from both regions mingle.
○ Examples: Muskeg (wetland transition between aquatic and terrestrial),
bogs, and fens.
● Ecological Niche: The specific role or "job" an organism plays within its habitat
to reduce competition for resources.
○ Niche Comparison (Hawks vs. Owls):
■ Hawks: Active during the day (diurnal), have long wings for
soaring, and rely on color change detection for hunting.
■ Owls: Active at dusk and dawn (crepuscular/nocturnal), have
short/broad wings for maneuverability, and rely on high auditory
function and motion detection.
● Competition:
○ Interspecific: Competition between different species for the same
resources.
I. The Biosphere and Systems
● The Biosphere: Often called the "living globe," it is the system of water
(hydrosphere), land (lithosphere), and air (atmosphere) that contains all living
and non-living things.
● System Types:
○ Open System: Exchanges both matter and energy with its surroundings.
○ Closed System: Exchanges energy but not matter. Earth is considered a
closed system because matter is constant while energy flows through it.
○ Isolated System: Exchanges neither matter nor energy.
● Dynamic Equilibrium: A state of balance where systems constantly adjust to
changes to maintain stability within the closed system of Earth.
● Gaia Hypothesis: Proposed by J.E. Lovelock. It suggests Earth functions like a
single living body where the biotic community is interconnected with the abiotic
environment.
II. Solar Radiation and Albedo
● Energy Source: The Sun is the primary energy source for the biosphere.
● Electromagnetic Radiation (EMR): Energy travels as waves; shorter
wavelengths carry more energy (e.g., UV) and can damage living matter, while
longer wavelengths (e.g., infrared) carry less.
● Albedo: The extent to which an object reflects light.
○ High Albedo: Light-colored surfaces (like polar ice caps) reflect more
energy and absorb less.
○ Low Albedo: Dark colors (like open water or forests) absorb more energy
and reflect less.
● Atmospheric Control: The atmosphere (troposphere, stratosphere with its
ozone layer) filters incoming energy, reflecting some and absorbing others before
it reaches the surface.
III. Energy Transfer and Trophic Levels
● Photosynthesis (PS): Plants convert solar energy into chemical energy
(glucose).
○ Equation: 6𝐶𝑂2 + 6𝐻2𝑂 + 𝑒𝑛𝑒𝑟𝑔𝑦 → 𝐶6𝐻12𝑂6 + 6𝑂2
● Cellular Respiration (CR): Organelles (mitochondria) in both plants and animals
convert glucose into usable energy (ATP) and heat.
○ Equation: 𝐶6𝐻1206 + 6𝑂2 → 6𝐶𝑂2 + 6𝐻2𝑂 + 𝑒𝑛𝑒𝑟𝑔𝑦
, ● Chemosynthesis: Occurs in deep-sea vents or caves where bacteria produce
organic compounds without sunlight using inorganic chemicals like 𝐻2 or 𝑁𝐻3.
● Thermodynamics:
○ First Law: Energy is neither created nor destroyed, only converted.
○ Second Law: Energy conversions are never 100% efficient; some energy
is always lost as heat.
● Trophic Levels: Categorization based on energy gain:
○ Producers (Autotrophs): First level; make their own food.
○ Consumers (Heterotrophs): Feed on others (Primary = herbivores,
Secondary/Tertiary = carnivores/omnivores).
○ 10% Rule: Only about 10% of energy is transferred from one trophic level
to the next; the rest is lost through waste, digestion, and heat from
respiration.
● Ecological Pyramids: Models representing relationships between levels:
○ Pyramid of Numbers: Based on the quantity of organisms.
○ Pyramid of Biomass: Based on the total dry mass of living material.
○ Pyramid of Energy: Always upright because energy is lost at each level.
IV. Matter Cycling (Biogeochemical Cycles)
Matter must cycle because there is no external source for it, unlike energy.
● Hydrologic Cycle: Moves water through evaporation, transpiration (release from
plants), condensation, and precipitation.
○ Leaching: Minerals are dissolved and carried away by water moving
through soil.
● Carbon and Oxygen Cycles: These are tightly linked through PS and CR.
Carbon is stored in the atmosphere (𝐶𝑂2), oceans, and the Earth's crust
(limestone, fossil fuels).
● Nitrogen Cycle:
○ Nitrogen Fixation: Bacteria or lightning convert atmospheric 𝑁2 into
nitrates (𝑁𝑂3) that plants can use.
○ Denitrification: Anaerobic bacteria convert nitrates back into 𝑁2 gas.
● Phosphorus Cycle: Cycles between rocks (long-term geochemical phase) and
living organisms (short-term biological phase) through weathering and
decomposition.
V. Biosphere Interactions and Human Impact
● Levels of Organization: Biosphere → Biome → Ecosystem → Community →
Population → Species.
, ● Niche vs. Habitat: A habitat is the physical "address" of an organism, while a
niche is its functional "role" or "job".
● Indicator Species: Sensitive organisms, like frogs, that provide early warning
signs of ecosystem stress.
● Species at Risk:
○ Special Concern: Low numbers at the edges of its range.
○ Threatened: Likely to become endangered if factors aren't reversed.
○ Endangered: Close to extinction.
○ Extirpated: No longer exists in a specific area but found elsewhere.
● Human Disturbances:
○ Biomagnification: The buildup of toxins (like DDT) in higher trophic
levels.
○ Eutrophication: Excess nutrients (fertilizers) in water cause algae
blooms, which deplete oxygen and kill aquatic life.
○ Monoculture: Growing only one crop reduces biodiversity and depletes
soil nutrients.
Unit B: Ecosystems and Population Change
I. Ecosystem Dynamics & Interactions
● Definition of Ecosystem: An ecological region where communities of plants,
animals, and microbes interact with their abiotic environment.
● Ecotone: A transitional area between two different ecosystems.
○ Characteristics: Often contains higher biodiversity than the individual
ecosystems because species from both regions mingle.
○ Examples: Muskeg (wetland transition between aquatic and terrestrial),
bogs, and fens.
● Ecological Niche: The specific role or "job" an organism plays within its habitat
to reduce competition for resources.
○ Niche Comparison (Hawks vs. Owls):
■ Hawks: Active during the day (diurnal), have long wings for
soaring, and rely on color change detection for hunting.
■ Owls: Active at dusk and dawn (crepuscular/nocturnal), have
short/broad wings for maneuverability, and rely on high auditory
function and motion detection.
● Competition:
○ Interspecific: Competition between different species for the same
resources.
