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Our Environment - Eco-system

Grade 10CBSE

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

🔑Concepts

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An ecosystem consists of biotic components (living organisms like plants, animals, and decomposers) and abiotic components (physical factors like temperature, rainfall, wind, soil, and minerals).

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Producers (Autotrophs) like green plants capture solar energy and convert it into chemical energy through photosynthesis: 6CO2+12H2O→SunlightChlorophyllC6H12O6+6H2O+6O26CO_2 + 12H_2O \xrightarrow[Sunlight]{Chlorophyll} C_6H_{12}O_6 + 6H_2O + 6O_2.

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Energy flow in an ecosystem is always unidirectional, moving from producers to various levels of consumers and finally to decomposers.

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The 10%10\% Law states that only 10%10\% of the energy available at a particular trophic level is passed on to the next higher trophic level.

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Biological Magnification refers to the progressive accumulation of non-biodegradable chemicals (like pesticides) at each trophic level, reaching maximum concentration in the tertiary consumers (usually humans).

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The Ozone layer (O3O_3) at higher levels of the atmosphere protects Earth from harmful ultraviolet (UVUV) radiation. It is formed by the action of UVUV rays on oxygen molecules: O2→UVO+OO_2 \xrightarrow{UV} O + O followed by O+O2→O3O + O_2 \rightarrow O_3.

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Chlorofluorocarbons (CFCsCFCs) are primarily responsible for the depletion of the ozone layer.

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Waste is categorized into Biodegradable (can be broken down by biological processes) and Non-biodegradable (cannot be broken down by bacteria or saprophytes).

📐Formulae

Energy at next trophic level=10%×Energy at current trophic level\text{Energy at next trophic level} = 10\% \times \text{Energy at current trophic level}

O2→UV radiationO+OO_2 \xrightarrow{UV \text{ radiation}} O + O

O+O2→O3 (Ozone)O + O_2 \rightarrow O_3 \text{ (Ozone)}

6CO2+12H2O→LightC6H12O6+6H2O+6O26CO_2 + 12H_2O \xrightarrow{\text{Light}} C_6H_{12}O_6 + 6H_2O + 6O_2

💡Examples

Problem 1:

If 20,000 J20,000\ J of energy is available at the producer level (T1) in a food chain, how much energy will be available to the secondary consumer (T3)?

Solution:

  1. Energy at Producer level (T1T_1) = 20,000 J20,000\ J.
  2. Energy at Primary Consumer level (T2T_2) = 10% of 20,000=10100×20,000=2,000 J10\% \text{ of } 20,000 = \frac{10}{100} \times 20,000 = 2,000\ J.
  3. Energy at Secondary Consumer level (T3T_3) = 10% of 2,000=10100×2,000=200 J10\% \text{ of } 2,000 = \frac{10}{100} \times 2,000 = 200\ J.

Explanation:

According to Lindeman's 10%10\% Law, only 10%10\% of the energy is transferred to the next level, while 90%90\% is lost as heat to the environment or used for metabolic processes.

Problem 2:

In a food chain consisting of Grass →\rightarrow Grasshopper →\rightarrow Frog →\rightarrow Snake →\rightarrow Hawk, which organism will have the highest concentration of a non-biodegradable pesticide like DDTDDT?

Solution:

The Hawk (the top carnivore/tertiary consumer) will have the highest concentration of DDTDDT.

Explanation:

This occurs due to Biological Magnification. Since DDTDDT is non-biodegradable, it cannot be excreted or metabolized. As the Hawk eats several snakes, each of which has eaten several frogs, the chemical accumulates increasingly at each successive trophic level.