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Notes

Ecology & Ecosystems

Definition/Introduction

An ecosystem is defined as a community of living organisms and their physical environment interacting as a system. This includes all the biotic (living) and abiotic (non-living) components that interact in a given area.

Ecological Concepts

**Primary Producers:** Organisms that produce energy from sunlight or inorganic substances. For example, phytoplankton in oceans.

**Food Chains and Food Webs:** Food chains illustrate the flow of energy from one organism to another, while food webs show the interconnectedness of different food chains.

Classification/Types of Ecosystems

1. **Terrestrial Ecosystems:** Includes forests, grasslands, deserts, and tundras.

2. **Aquatic Ecosystems:** Includes freshwater ecosystems (lakes, rivers) and marine ecosystems (oceans, coral reefs).

Important Provisions/Features

**Photosynthesis:** The process by which primary producers convert light energy into chemical energy.

**Energy Flow:** Energy flows through an ecosystem in a one-way stream, from primary producers to various consumers.

Landmark Judgments

(Not applicable for this topic as it pertains to ecology and ecosystems.)

Amendments

(Not applicable for this topic as it pertains to ecology and ecosystems.)

Comparison Tables

| Feature | Terrestrial Ecosystem | Aquatic Ecosystem |

|---------|----------------------|-------------------|

| Dominant Producers | Plants | Phytoplankton |

| Primary Consumers | Herbivores | Zooplankton |

| Secondary Consumers | Carnivores | Fish |

UPSC Exam Focus

Understanding the interdependence of organisms within an ecosystem.

The role of primary producers and the impact of their loss (e.g., phytoplankton).

The concept of ecological niches and their importance in biodiversity.

### PYQ Analysis

Questions often focus on:

The definitions and characteristics of ecosystems.

The impact of human activities on ecosystems.

Understanding different types of ecosystems and their productivity.

Key Concepts

Ecosystem - A community of organisms together with the environment in which they live.

Ecological Niche - Describes not only the physical space occupied by an organism, but also its functional role in the community of organisms.

Primary Producers - Organisms that produce their own food, primarily plants, algae, and some bacteria.

Food Chain - A linear sequence of organisms through which nutrients and energy pass as one organism eats another.

Food Web - A complex network of feeding relationships among various organisms in an ecosystem.

Biomes - Large ecological areas on the Earth's surface, with flora and fauna adapting to their environment.

Symbiotic Relationships - Close and long-term interactions between different biological species.

Ecosystem Productivity - The rate at which energy is converted by photosynthetic and chemosynthetic autotrophs to organic substances.

Important Facts

•[2012] Phytoplankton is crucial for marine ecosystemsPhytoplankton are primary producers in oceans, and their loss affects carbon sinks and food chains.

•[2015] Mangroves have the highest productivityMangroves are known for their high productivity compared to other ecosystems like grasslands and oceans.

•[2021] Symbiotic relationships include Cnidarians and FungiThese organisms often engage in symbiotic relationships, providing mutual benefits to each other.

•[2011] Marine upwelling zones increase productivityNutrient-rich waters brought to the surface enhance marine productivity.

•[2021] Lichens and mosses can survive without soilThese organisms are often found in harsh environments where soil is absent.

•[2013] Ecological niche describes organism's roleThe ecological niche encompasses both the physical space and the functional role of an organism in its community.