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Ecology - Ecosystems and Biomes

Grade 9IB

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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Ecosystems consist of biotic (living) and abiotic (non-living) components interacting as a system. Abiotic factors include temperature, pHpH, sunlight intensity, and moisture levels.

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The hierarchy of biological organization in ecology is: Organism →\rightarrow Population →\rightarrow Community →\rightarrow Ecosystem →\rightarrow Biome →\rightarrow Biosphere.

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Energy flows through an ecosystem starting from solar radiation, which is captured by producers through photosynthesis: 6CO2+6H2O+light→C6H12O6+6O26CO_2 + 6H_2O + light \rightarrow C_6H_{12}O_6 + 6O_2.

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Trophic levels represent the feeding positions in a food chain. The 10%10\% rule states that only approximately 10%10\% of the energy available at one trophic level is transferred to the next, while the rest is lost as heat or used for metabolic processes.

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Biomes are large-scale ecosystems defined by their climate, specifically average temperature (measured in ∘C^\circ C) and annual precipitation (measured in mmmm). Examples include Tundra, Desert, and Tropical Rainforest.

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Nutrient cycling involves the movement of elements like Carbon (CC) and Nitrogen (NN) through the biosphere. Unlike energy, nutrients are recycled within the system.

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Symbiotic relationships include Mutualism (+/+)(+/+), Commensalism (+/0)(+/0), and Parasitism (+/−)(+/-).

📐Formulae

6CO2+6H2O→lightC6H12O6+6O26CO_2 + 6H_2O \xrightarrow{light} C_6H_{12}O_6 + 6O_2

NPP=GPP−RNPP = GPP - R

Energytransfer=Energylower level×0.10Energy_{transfer} = Energy_{lower\,level} \times 0.10

C6H12O6+6O2→6CO2+6H2O+ATPC_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + ATP

💡Examples

Problem 1:

In a specific grassland ecosystem, the primary producers (grasses) generate 50,000 kJ50,000\,kJ of energy. Calculate the energy available to the tertiary consumers (e.g., hawks) assuming the 10%10\% rule applies.

Solution:

The energy at the tertiary consumer level is 50 kJ50\,kJ.

Explanation:

Starting at the producer level: 50,000 kJ50,000\,kJ. Primary consumers (herbivores) receive 50,000×0.1=5,000 kJ50,000 \times 0.1 = 5,000\,kJ. Secondary consumers receive 5,000×0.1=500 kJ5,000 \times 0.1 = 500\,kJ. Tertiary consumers receive 500×0.1=50 kJ500 \times 0.1 = 50\,kJ. This demonstrates the significant loss of energy at higher trophic levels.

Problem 2:

Identify the chemical equation for cellular respiration and explain its role in the carbon cycle.

Solution:

C6H12O6+6O2→6CO2+6H2O+ATPC_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O + ATP

Explanation:

Cellular respiration is the process by which organisms break down glucose (C6H12O6C_6H_{12}O_6) to release energy. In the carbon cycle, this process releases carbon dioxide (CO2CO_2) back into the atmosphere, making it available for producers to use in photosynthesis.