CBSE Class 12 Biology Chapter 14 Revision Notes Part 2

Chapter 14: Ecosystems Revision Notes Part 2

The ecosystem is the basic scientific study of nature. What is an ecosystem? It is an environment that is defined physically and is made with two inseparable components.

The biotic or the abiotic include physical environment features like other organisms, temperature, climate, nutrient concentration, etc. The biotic or the biocenosis is a set of living organisms like plants and animals that interact with each other constantly and are in an interdependent situation.

Ecosystem – Structure and function

The ecosystem is made up of abiotic and biotic components. The abiotic components are the basic organic compounds, and the biotic components are the producers, decomposers, and consumers.

The natural ecosystem is a balanced system. The interactions between the varied organisms make the ecosystem function and give it stability. The herbivores consume grass and feed the soil with their droppings; the grass grows again, giving the system a balance. The ecosystem is not static and constantly evolves because it is dependent on dynamic processes.

The biotic components are living organisms that interact with the environment and transform it constantly. Animals make the soil compact and the plants give it humidity to regulate bacteria and temperature. This protects the animals from diseases. The ecosystem also evolves because of unforeseen events. Any natural or climatic phenomenon will transform the environment. The biocenosis lets the living organisms adapt to changes and new constraints.

The ecosystem wants stability, but it never gets it successfully. The natural imbalance offsets each other permanently. Some ecosystems evolve slowly which the others transform fast. At times the ecosystem may also disappear.


Productivity is the quantity of organic matter accumulated in a time unit. These are classified as primary productivity, which is the green plants. Secondary productivity, which is the consumers, and net productivity, which is the storage rate of the organic matter.


Decomposition processSource

Decomposition is the attacking of the dead parts of the producers and the consumers, and this degrades the substance of the complex organ into a simple compound.

Energy Flow in the Ecosystem

According to the law of the conservation of energy, energy can neither be created nor can it be destroyed. It can just be transferred or transformed from one to another. This stands true in the ecosystem as well.

Ecosystem and Human Activities

Human activities impacting the ecosystemSource

There is an ongoing thirst in humans to modify and transform the natural process of the ecosystem. Even when they transform any plain land to grow cereals they are modifying the ecosystem. At times the ecosystem is changed from its original form.

There has been a significant impact of human beings on the ecosystem. Changes are being caused because of climate. Trees are cut and this makes it difficult for the species to survive. When a dam is built, it disrupts the water distribution and affects those species that live in this course of water.

Why is it important to preserve the ecosystem?

Like any living being, human beings are also dependent on the services of the natural ecosystem to survive. We get food from the ecosystem. The water that we drink comes from the ecosystem as well as the raw materials that we need for our day-to-day use is got from the ecosystem. To maintain our living system, the natural ecosystem must be preserved.

The quality of our food depends on the characteristics of the specific ecosystem. The vegetables and cereals only grow in certain climates and temperatures. A natural process like pollination is important. If these characteristics are changed then we may not be able to produce what we produce today. Many agricultural techniques manage the production of food. But using herbicides and pesticides and exhausting the water sources nearby will only lead to an imbalance in the ecosystem.


Ecosystem. Accessed on Dec 23, 2021


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