Lesson 45 + 46: Energy and Energy Flow in Ecosystems
I. Energy Flow in Ecosystems:
1. Common Energy Pathway:
- Sunlight → Autotrophs → Heterotrophs → Energy returns to the environment
Note:
- Sunlight is the primary source of energy for all ecosystems.
- Autotrophs (plants, algae) absorb sunlight to synthesize organic matter, providing food for heterotrophs.
- Heterotrophs (animals, fungi, bacteria) consume autotrophs or other heterotrophs to obtain energy.
- Energy is transferred from lower trophic levels to higher trophic levels, but the amount of energy transferred decreases due to losses during metabolism, growth, and reproduction.
- Ultimately, energy is returned to the environment as heat.
2. Ecological Efficiency:
- The percentage of energy transferred from one trophic level to the next.
- Formula: Ecological efficiency = (Energy accumulated at higher trophic level / Energy accumulated at lower trophic level) x 100%
- Average ecological efficiency is about 10%, meaning only about 10% of energy is transferred from one trophic level to the next.
3. Reasons for Energy Loss in Ecosystems:
- Organisms cannot utilize all energy: Some energy is excreted as waste (feces, urine).
- Energy lost through respiration: Organisms expend energy to maintain life functions such as respiration, movement, and foraging.
- Energy loss through death: Some energy is lost when organisms die and are decomposed by microorganisms.
II. Energy Sources:
1. Clean Energy Sources:
- Solar energy: Renewable, non-polluting energy source.
- Wind energy: Renewable, non-polluting energy source.
- Wave energy: Renewable, non-polluting energy source.
- Tidal energy: Renewable, non-polluting energy source.
2. The Biosphere Exists and Thrives due to Energy:
- The Sun: The sun provides light energy for plants to perform photosynthesis, ultimately fueling all other life.
III. Producers:
1. Producers utilize:
- Visible light: Producers use sunlight, specifically visible light, for photosynthesis.
2. Primary Productivity:
- The rate at which organic matter is created by producers in a given time.
- Produced by: Producers (plants, algae).
3. Organisms in Food Chains Receive Energy from the Abiotic Environment:
- Producers: Producers act as a bridge between the abiotic and biotic environments, providing energy for heterotrophs.
IV. Resources:
1. Non-renewable Resources:
- Coal: Formed from the remains of ancient plants buried underground over millions of years, a non-renewable resource.
- Oil: Formed from the remains of marine organisms buried underground over millions of years, a non-renewable resource.
V. Biodiversity:
- The richness of gene pools, species, and natural ecosystems.
- Important Roles:
- Provides food, medicines, and building materials.
- Maintains ecological balance.
- Preserves genetic diversity.
Note:
- Protecting biodiversity is protecting life on Earth.
- Conserving clean energy sources and using energy efficiently is protecting our environment.
- Understanding energy flow in ecosystems helps us utilize resources effectively and protect the environment.
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