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How Nature Works in Harmony - Who All Live Together in Nature?

Grade 8CBSE

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

🔑Concepts

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Ecosystem: A functional unit of nature where living organisms (biotic factors) interact among themselves and also with the surrounding physical environment (abiotic factors like air, water, and soil).

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Biotic Components: These include all living organisms such as plants (producers), animals (consumers), and microorganisms (decomposers).

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Abiotic Components: Non-living elements such as temperature, light, H2OH_{2}O (water), and soil nutrients that support life.

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Food Chain: A sequence of organisms through which energy is transferred. For example: Grass→Grasshopper→Frog→Snake→Eagle\text{Grass} \rightarrow \text{Grasshopper} \rightarrow \text{Frog} \rightarrow \text{Snake} \rightarrow \text{Eagle}.

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Food Web: A complex network of many interconnected food chains in an ecosystem, representing the actual feeding relationships.

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Trophic Levels: The distinct steps in a food chain where transfer of energy occurs. Producers occupy the 1st1^{st} trophic level, followed by primary consumers, secondary consumers, etc.

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Energy Flow: Energy flows unidirectionally from the sun to producers and then to consumers. Only 10%10\% of the energy is transferred to the next trophic level.

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Biodiversity: The variety of plant and animal life in a particular habitat. High biodiversity ensures a stable and harmonious ecosystem.

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Endemic Species: Species of plants and animals which are found exclusively in a particular area, such as the Giant Panda in China or the LemurLemur in Madagascar.

📐Formulae

Energy at higher level=10%×Energy at lower level\text{Energy at higher level} = 10\% \times \text{Energy at lower level}

En+1=10100×EnE_{n+1} = \frac{10}{100} \times E_{n}

Total Population Density=Total Number of Individuals (N)Total Area (A)\text{Total Population Density} = \frac{\text{Total Number of Individuals (N)}}{\text{Total Area (A)}}

💡Examples

Problem 1:

In a forest ecosystem, if the producers (plants) capture 20,000 J20,000\text{ J} of solar energy, calculate the amount of energy available to the tertiary consumer based on the 10%10\% law.

Solution:

  1. Producers (1st1^{st} level): 20,000 J20,000\text{ J}.
  2. Primary Consumers (Herbivores): 10100×20,000=2,000 J\frac{10}{100} \times 20,000 = 2,000\text{ J}.
  3. Secondary Consumers (Carnivores): 10100×2,000=200 J\frac{10}{100} \times 2,000 = 200\text{ J}.
  4. Tertiary Consumers: 10100×200=20 J\frac{10}{100} \times 200 = 20\text{ J}.

Explanation:

According to the 10%10\% Law, only 10%10\% of the energy stored in an organism is passed on to the next level. The rest is lost as heat during metabolic processes or through respiration.

Problem 2:

A sanctuary has a total area of 500 km2500\text{ km}^2. If the count of a specific deer species is 2,5002,500, find the population density of the deer.

Solution:

Density=2500500=5 deer/km2\text{Density} = \frac{2500}{500} = 5 \text{ deer/km}^2

Explanation:

Population density is the measurement of population per unit area. It helps scientists understand how crowded a habitat is and if resources are sufficient for everyone to live together in harmony.

Problem 3:

Calculate the total biomass remaining if a field produces 8,000 kg8,000\text{ kg} of grass and 7,250 kg7,250\text{ kg} is consumed by herbivores. Show the subtraction.

Solution:

8000−7250750\begin{array}{r} 8000 \\ -7250 \\ \hline 750 \end{array} The remaining biomass is 750 kg750\text{ kg}.

Explanation:

In an ecosystem, the balance between production (producers) and consumption (consumers) determines the sustainability of the habitat.