env sustainability notes

Topic: Life – Biodiversity & Conservation

🎯 Objectives

By the end of this lesson, you should be able to:

  • Define energy and distinguish between its different forms

  • Explain photosynthesis and respiration, including global patterns of Net Primary Productivity (NPP)

  • Understand trophic levels and how they relate to energy flow in ecosystems

⚡ Energy: The Foundation of Life

  • Powers our planet and shapes life patterns

  • Brings convenience & comfort: heating, transportation, electronics

🔑 Definition

  • Energy = the capacity to do work

🔄 Forms of Energy & Transformations

  1. Mechanical – movement-based energy (often from chemical transformations)

  2. Chemical – stored in molecular bonds

    • Found in: glucose (C₆H₁₂O₆), petroleum, batteries

  3. Electrical – flow of electrons through conductors

  4. Radiant – electromagnetic waves from the Sun

  5. Thermal – heat from vibrating and colliding atoms

Law of Energy Conservation: Energy cannot be created or destroyed, only transformed

🪵 Example: Burning wood →
Chemical energy → Thermal + Radiant energy

☀ Solar Energy & Life

  • The Sun is the ultimate source of energy

  • Radiant energy from the Sun:

    • Transformed into thermal energy (heat)

    • Used in photosynthesis to create chemical energy

🌿 Photosynthesis

  • Plants = Primary producers

  • Equation:
    CO₂ + H₂O + sunlight → C₆H₁₂O₆ (sugar) + O₂

  • Converts solar energy into usable chemical energy

🌬 Respiration

  • Plants (and all living things) use some energy for survival:
    C₆H₁₂O₆ + O₂ → CO₂ + H₂O + energy (ATP)

🔋 Net Primary Productivity (NPP)

  • NPP = energy left over after plant respiration

  • Supports all consumers in an ecosystem

🌍 Ecosystem Productivity

Ecosystem Type

NPP (kcal/m²/year)

Tropical Rainforest

9000

Estuary

9000

Swamps & Marshes

9000

Deciduous Temperate Forest

6000

Boreal Forest

3500

Savanna

3000

Temperate Grassland

2000

Polar Tundra

600

Desert

<200

📈 Productivity Increases with:

  • Precipitation

  • Sunlight

🌐 Energy Flow in Ecosystems

🔗 Trophic Levels

  • Levels in a food chain:

    • Producers → Consumers → Decomposers

  • Consumers: gain energy by eating others

  • Decomposers: break down dead organisms
    (e.g., fungi, bacteria, worms)

🕸 Food Webs

  • Interconnected food chains

  • Show the flow of energy and nutrient cycling

  • Producers: convert sunlight into energy through photosynthesis, forming the base of the food web. Consumers: organisms that obtain energy by eating other organisms, classified into primary (herbivores), secondary (carnivores), and tertiary consumers.