ecology study guide

Chapter 1: The Biosphere as a Closed System

Key Concepts

• Biosphere: The part of Earth where life exists, including land, water, and atmosphere.

• Equilibrium: A stable system where biotic and abiotic factors maintain balance over time.

• Biodiversity: The variety of life in an ecosystem, contributing to stability and resilience.

• Food Webs and Pyramids: Represent energy flow in ecosystems.

Food Webs and Energy Pyramids

• Trophic Levels:

  • Producers (Autotrophs) → Primary Consumers → Secondary Consumers → Tertiary Consumers

• Ecological Pyramids:

  • Energy Pyramid (shows energy loss at each level, only ~10% is passed on)

  • Biomass Pyramid (mass of organisms at each level)

  • Numbers Pyramid (population size at each level)

Chapter 2: Energy Flow in the Biosphere

Key Concepts

• Energy Flow: Sunlight → Producers (Photosynthesis) → Consumers → Decomposers

• Primary Productivity: The rate at which producers convert solar energy into chemical energy.

• The First and Second Laws of Thermodynamics:

  • Energy cannot be created or destroyed, only transformed.

  • Every energy transfer loses some energy as heat.

Chapter 3: The Cycling of Matter in the Biosphere

3.1 – Hydrologic Cycle (Water Cycle)

Nelson Reference: Pages 42-45

Importance of Water

• Universal solvent

• Essential for biochemical reactions

• Regulates climate and transports nutrients

Properties of Water

• Polarity: Water is a polar molecule, meaning it has a partial positive charge on hydrogen and a partial negative charge on oxygen.

• Cohesion & Adhesion: Water molecules stick together and to other surfaces.

• High Specific Heat: Water absorbs heat without major temperature changes.

Processes in the Hydrologic Cycle

• Precipitation: Water falls from clouds as rain, snow, sleet, or hail.

• Transpiration: Water evaporates from plant leaves.

• Percolation: Water filters through soil into groundwater.

• Water Table: The underground level where soil is saturated with water.

• Leaching: Water carries nutrients or pollutants downward through soil.

Diagram of the Hydrologic Cycle:
(Include a labeled diagram of the water cycle with arrows showing precipitation, transpiration, percolation, and runoff.)

3.1 – Acid Deposition, Water Pollution, and Fresh Drinking Water

Nelson Reference: Pages 46-47

Acid Deposition

• Causes:

  • Sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) from burning fossil fuels react with water to form acid rain.

• Effects:

  • Lowers pH of water bodies, harming aquatic life.

  • Damages plants, soil, and buildings.

• Technologies to Reduce Acid Deposition:

  • Scrubbers in power plants remove SO₂.

  • Catalytic converters in cars reduce NOₓ emissions.

Water Pollution

• Mercury & Lead: Heavy metals from industry and mining that contaminate water.

• Other Toxins: Pesticides, oil spills, and microplastics.

Visual of Acid Deposition Effects:
(Include an image of acid rain damage on forests or lakes.)

3.2 – The Carbon and Oxygen Cycle

Nelson Reference: Pages 49-51

Importance of Carbon

• Carbon is the backbone of organic molecules (carbohydrates, proteins, fats, DNA).

Processes in the Carbon Cycle

• Photosynthesis: Plants use CO₂, sunlight, and water to make glucose.

• Cellular Respiration: Organisms break down glucose, releasing CO₂.

• Combustion: Burning fossil fuels releases CO₂.

• Reservoirs of Carbon:

  • Inorganic: Atmosphere, oceans, rocks (limestone).

  • Organic: Living organisms, dead matter (peat, fossil fuels).

Oxygen Cycle

• Oxygen Gas (O₂): Produced in photosynthesis, used in respiration.

• Ozone (O₃): Protective layer in the stratosphere.

• Oxygen in Lithosphere: Found in minerals and oxides.

Diagram of the Carbon and Oxygen Cycle:
(Include a labeled diagram showing CO₂ movement through photosynthesis, respiration, and combustion.)

3.2 – Human Impact on the Carbon Cycle

Nelson Reference: Pages 52-56

Deforestation & Burning Rainforests

• Reduces CO₂ absorption and releases stored carbon.

The Greenhouse Effect & Global Warming

• Greenhouse Gases: CO₂, methane (CH₄), and water vapor trap heat in the atmosphere.

• Effects of a Warmer Climate:

  • Rising sea levels, extreme weather, ecosystem disruptions.

The Albedo Effect

• Light-colored surfaces (ice, snow) reflect sunlight; dark surfaces absorb it.

• Melting ice reduces albedo, increasing warming.

Stromatolites

• Ancient bacteria that helped produce oxygen billions of years ago.

Diagram of the Greenhouse Effect:
(Include a labeled diagram showing heat being trapped by greenhouse gases.)

3.3 – The Nitrogen Cycle

Nelson Reference: Pages 60-62

Importance of Nitrogen

• Essential for amino acids, proteins, and DNA.

Processes in the Nitrogen Cycle

• Nitrogen Fixation:

  • Lightning or bacteria convert nitrogen gas (N₂) into nitrates (NO₃⁻).

  • Legumes host nitrogen-fixing bacteria.

• Purpose of Crop Rotation:

  • Helps replenish soil nitrogen.

• Decomposition:

  • Organic matter breaks down into ammonia (NH₃).

• Denitrification:

  • Anaerobic bacteria convert nitrates back to N₂ gas.

Diagram of the Nitrogen Cycle:
(Include a labeled diagram showing nitrogen fixation, decomposition, and denitrification.)

3.3 – The Phosphorus Cycle and Fertilizer Run-off

Nelson Reference: Pages 62-64, 115-116, 119

Importance of Phosphorus

• Needed for DNA, ATP, and bones.

Phosphorus Cycle

• Short-term Cycle:

  • Phosphates are absorbed by plants, eaten by animals, and returned to soil through waste.

• Long-term Cycle:

  • Phosphates accumulate in rock and are released by weathering.

Agriculture and Nutrient Cycles

• Fertilizers: Boost crop growth but can cause pollution.

• Fertilizer Run-off & Eutrophication:

  • Excess nutrients in water cause algae blooms.

  • When algae die, decomposition depletes oxygen, killing aquatic life.

Diagram of Eutrophication:
(Include an image of an algal bloom leading to oxygen depletion.)

Final Review Tips:

• Memorize Key Terms & Definitions.

• Understand Each Cycle’s Steps & Their Importance.

• Review Diagrams for Visual Understanding.

• Practice Explaining Processes in Your Own Words.