Ecosystem

An ecosystem is a complex system where living organisms interact with each other and their non-living surroundings. The final balance of nature helps us understand how different species live together and affect their environment. Ecosystems is an important chapter of Biology included in class 12 CBSE. This chapter is also important for students preparing for exams such as NEET, AIIMS, nursing, and paramedical. The article explains many basic aspects of ecosystems, including their elements, characteristics, and composition, which explain the very basic functions of these natural systems.

Important Topics of Ecosystem

• What is an Ecosystem?
• Structure of Ecosystem
• Types of Ecosystem
• Ecosystem Functions
• Important Concepts - Food Chain, Food Web, Ecological Pyramid

Overview of the Chapter

An ecosystem is a basic unit of activity in which living things interact (living and nonliving), both of which are necessary for the preservation of life on our planet which includes plants, bacteria, animals and all other living things which are included in soil, land, air, water, dust, and other parts of nature.

If we try to study ecology in detail, then the basic unit that starts is the Ecosystem. Ecosystem research is about how living things coexist and how energy flows through the ecosystem of ecosystems. It also learns how a living thing lives in a harmful or beneficial relationship to survive sustainably.

It is evident from nature that the structure of ecosystem can be large or even small. It usually depends on the number of the given abiotic components found in the environment. The ecosystem north or south of the logs is devoid of plants and animals compared to the tropical climate of the forest due to the extreme weather conditions the animals face. Only ecosystems will be able to build the Ecosystem. Overall, it is understood that different ecosystems can form a biosphere.

Read More:

• MCQ Practice on Ecosystem
• Productivity in Ecosystem
• Ecosystem Services
• Biodiversity and Conservation

What is an Ecosystem?

An ecosystem may be defined as a community of living organisms interacting with one another and their nonliving environment in some area. These interactions give rise to a complicated web of relationships that sustains the ecosystem through the flow of energy and cycling of nutrients.

Units of an Ecosystem

An Ecosystem is made of several interrelated units:

Habitat

• A habitat is the natural environment in which an organism lives and thrives.

• It comprises both the biotic and abiotic elements that an organism needs to have to survive, like food, water, or shelter.

• For example, forests are habitats to a uniquely large diversity of species, from birds and mammals to insects and plants, while deserts provide habitat for organisms like cacti, lizards, and scorpions.

Niche

• A niche means the function and status a species occupies in its environment, encompassing all interactions between the species, biotic, and abiotic variables.

• What the species eats and how it procures food, how it interacts with other organisms—these make a niche.

• For instance, pollination, collection of nectar, and pollen are the niche activities of the bee.

Community

• A community consists of different species that live together in a common habitat, but the interactions among its members define the structure and dynamics.

Population

• A population may be defined as a group of interbreeding individuals of the same species that either is or has the potential to be, isolated in some particular locale.

• Population dynamics investigate changes in these populations over time and space, due to events such as birth, death, immigration, and emigration.

• For example, some models describe the growth of a population, like exponential growth models that describe very fast-growing populations with no limiting factors, or logistic growth models that stabilise the carrying capacity of the environment due to limiting factors such as food and space.

Importance of Ecosystem

Ecosystems are, therefore, mandatory in keeping life on earth. They offer very important services like food, water, oxygen, and raw materials production. They control the climate, reuse nutrients, and protect biodiversity. Healthy, diverse ecosystems ensure survival.

Types of Ecosystem

In ecology, an ecosystem is divided into different types based on region or on the basis of nature such as land or water. It can also be compiled based on the amount of energy used by the Ecosystem.

The categories in the basic ecosystem are:

• Terrestrial Ecosystem
• Aquatic Ecosystem

All other species will fall into any of these natural systems and therefore can be divided into different species.

Terrestrial Ecosystem

These natural systems can only be found in the world. Different species of the earth will have different natural conditions based on climate, temperature, species of living things, energy flow, food chain and other factors.

Ecosystems have a relatively smaller percentage of water than aquatic Ecosystems, and there is also a better availability of sunlight as a major source of energy. The types of ecosystems on Earth are:

Forest Ecosystem: These ecosystems are dense for biodiversity. It has the highest number of living things per square mile. It is important to preserve this ecological system as many rare earth species are found here. Most of the world's oxygen is found in forests.

Desert Ecosystem: Deserts are described as living organisms that receive less than 25cm of rain in extreme weather. Even at high temperatures, some organisms can withstand high temperatures and plants need very little water to survive.

Mountain Ecosystem: Mountains are subtropical regions with scattered vegetation. It also has a very bad climate, and the animals of these regions have fur on their skin to withstand the cold weather.

Grassland Ecosystem: mainly consists of shrubs, herbs, and a few dense forests such as forests. These basically include grazing animals, insects, and herbivores. Temperatures are not too high for these ecosystems. There are two main types: savannas and plains. Savannas are tropical grasslands. It will dry out at certain times of the year with many predators and pastures. The plains are cool grass, with no big trees and no trees.

Aquatic Ecosystem

The aquatic ecosystem is largely made up of animals and aquatic life, such as lakes, oceans and seas. Aquatic animals, fish, and sea creatures all fall under this biological system. As water is plentiful, living things survive using oxygen dissolved in water. This ecosystem is much larger than the earth's ecosystem as it covers most of the earth. The two types of aquatic ecosystems are:

Marine Ecosystem: It covers all oceans and seas and makes up about 71% of the world. About 97% of the world's water falls under this category. Sharks, whales, dolphins, seals, walruses, and many others fall under this system of things.

Freshwater Ecosystem: Combines all rivers, lakes, lakes, and freshwater sources. This accounts for 0.8% of the world's water and 0.009% of the world's total water supply. There are three types of this ecosystem lotic system in which water flows faster, e.g., rivers. A lentic system where water stays stagnant, e.g., ponds and ponds. Wetlands where the soil remains full most of the time.

NCERT Notes Subject Wise Link:

• NCERT notes Class 12 Maths
• NCERT notes Class 12 Physics
• NCERT notes Class 12 Chemistry
• NCERT notes Class 12 Biology

Components of Ecosystem

The ecosystem has two related components mentioned below:

• Abiotic components
• Biotic components

Abiotic Components

Abiotic factors are the nonliving parts of an ecosystem that have a huge effect on living organisms within it. The factors create an environment in which biotic ones operate and play a very important role in shaping the structure and functionality of the ecosystem. Abiotic factors can be broadly classified into two major groups: physical and chemical factors.

Physical Factors

Sunlight is the fundamental source of energy in almost every ecosystem. It triggers photosynthesis—such is the process whereby producers like plants and algae turn light energy into chemical energy for storage in glucose.

Temperature appears to be one of the major controlling factors for metabolic rates, enzyme activity, and other physiological functions of living organisms.

Water is indispensable for all living organisms because it is the primary constituent of cells and a medium for the majority of biochemical reactions. The types of vegetation and the different species of animals are a function of the water availability.

Soil is a very complex mixture of mineral particles, organic matter, water, air, and living organisms. Its composition varies widely and influences the types of plants that may be grown in it.

Chemical Factors

• pH is the measure of acidity or alkalinity of substances. It ranges on a scale from 0 to 14, where 7 is considered neutral, below 7 is acidic, and above 7 is alkaline.

• Minerals are inorganic elements essential for various physiological functions both in plants and animals. Common minerals include calcium, magnesium, potassium, and iron.

• Gases: The type of organisms that are found in either water or soil can at times be determined by the availability of oxygen. In aquatic ecosystems, this could result in hypoxia. It can affect the rate of photosynthesis and thus the productivity of an ecosystem. CO₂ concentration within the atmosphere controls the greenhouse effect and global climate patterns.

Biotic Component

All living organisms that coexist, interrelate, and interact with one another, as well as the abiotic factors of the ecosystem, are termed the biotic components. Those can be producers, consumers, and decomposers. All of these contribute to balancing the ecosystem.

Producers (Autotrophs)

Producers are organisms able to obtain their food from photosynthesis or chemosynthesis and form the first trophic level in an ecosystem. They are therefore the energy sources for all other organisms.

Photosynthetic Producers: Plants, algae, and certain bacteria—for example, cyanobacteria. They use sunlight, carbon dioxide, and water to synthesise glucose and oxygen. For example, primary producers are green plants, grass, trees, and phytoplankton in aquatic ecosystems.

Chemosynthetic Producers: Connected mostly to extreme environments, for example, deep-sea vents, these include some bacteria that produce food through chemical reactions between inorganic molecules.

Consumers (Heterotrophs)

Consumers are organisms that cannot prepare their food and obtain energy by consuming other organisms. Consumers are categorised based on their diets as follows:

Primary Consumers (Herbivores): These are organisms that get energy directly from producers. Examples of these are cows, deer, and caterpillars that eat plants.

Secondary Consumers (Carnivores): These are the organisms that consume the primary consumers. Examples are lions, snakes, and frogs that eat herbivores.

Tertiary Consumers (Top Predators): These are carnivores that feed on other carnivores. Examples are eagles, sharks, and orcas, which feed on the secondary consumers.

Omnivores: These are consumers who developed the trait of consuming both plants and animals. Examples are humans, bears, and pigs.

Decomposers (Detritivores)

Decomposers, or detritivores, form a core constituent of an ecosystem and serve to break down dead organic material to return the nutrients to the environment. In this way, the process is important in maintaining self-sustaining and healthy ecosystems by guaranteeing a constant supply of basic elements required by producers.

Bacteria: These microorganisms are very effective decomposers that are almost found everywhere on the planet. They are crucial in degrading complex organic compounds, namely proteins, carbohydrates, and lipids, into simpler molecules. In the case of cellulose, for example, which is a polymeric compound, one of the chief constituents of plant cell walls, and indigestible to most animals, there are some specialised bacteria involved in breaking it down.

• Aerobic bacteria: These are organisms that require oxygen to live and multiply in, for instance, soil and water conditions with adequate availability of oxygen. They decompose the organic matter quickly and produce carbon dioxide, water, and minerals.

• Anaerobic bacteria: do not use oxygen for their survival and are found in places such as deep sediments, waterlogged soils, or in the digestive tracts of animals. They decompose organic material more slowly with byproducts that are methane and other gases.

Fungi: They release enzymes that break down complicated organic materials like lignin and cellulose into simpler compounds. Fungi can degrade some of the most resistant plant materials and are extremely important in forest ecosystems, which break down fallen logs and leaf litter.

• Saprophytic Fungi: These fungi derive nutriment from dead or decaying organic matter. A wide network of thread-like hyphae, penetrates the organic material, releasing enzymes outside that hydrolyse it before finally getting absorbed.

• Mycorrhizal Fungi: These are symbionts with plant roots. Although they don't themselves act as decomposers, they assist in nutrient cycling by breaking down organic matter into the soil, where they become more readily available to plants.

Detritivores: Earthworms are Detritivores by nature. They ingest high amounts of soil along with organic litter, break it in the digestive systems, and excrete it in the form of casting rich in nutrients. This aerates the soil, improves its structure, and enhances nutrient availability to plants.

NCERT Books Link:

• NCERT book for class 11 Biology
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Ecosystem Functions

The primary function of any ecosystem is the exchange of energy from one kind of life to another, which keeps running in a circle and preserves the entire life of the planet. Without a highly balanced biological system, there would be no life on Earth at all.

Energy Flow

• The energy flow in an ecosystem begins with the ability of producers to capture solar energy by photosynthesis.

• Plants convert solar energy into chemical energy, and the latter is passed on to the consumers.

• The transference of energy from the producers to primary consumers is to the secondary consumers carnivores, and finally to the tertiary consumers, the top predators.

Nutrient Cycling

• Nutrient cycles refer to those processes that work towards the balancing of major elements within an ecosystem.

• The carbon cycle reports on the movements of carbon between the atmosphere, hydrosphere, lithosphere, and biosphere.

• The nitrogen cycle shows how nitrogen is converted into various chemical forms as it moves through the atmosphere terrestrial, and marine ecosystems.

• Water Cycle describes the continuous movement of water on, above, and below the surface of the Earth.

• The phosphorus cycle describes the pathway phosphorus takes through rocks, water, soil, and living organisms.

Important Ecological Concepts

Ecological concepts help in understanding the connection of organisms with their environment and balance maintenance that keeps an ecosystem thriving.

Food Chain

A food chain is a linear sequence that shows the flow of energy and nutrients from one organism to the next in an ecosystem.

• Producers: The very bottom of the food chain; usually plants or algae photosynthesizing for energy.

• Primary Consumers: Herbivores that consume producers.

• Secondary Consumers: Carnivores consume primary consumers.

• Tertiary Consumers: Higher-level carnivores which consume the secondary consumers

• Decomposers: Organisms, mostly bacteria and fungi, involved in the breaking of dead organisms to return nutrients to the ecosystem.

Diagram: Food Chain

Ecological Pyramids

An ecological pyramid is a graphic representation that details or highlights the different trophic levels of an ecosystem in a specific locality.

• Pyramid of Numbers: The number of individual organisms in each trophic level is described. Often shows vast numbers of producers and progressively fewer consumers.

• Pyramid of Biomass: It describes the total mass of living tissue associated with each trophic level. There is a decrease in the biomass from producers via intermediate consumers to final consumers.

• Pyramid of Energy: It describes energy at each trophic level. It shows that energy is lost at each level (approximately 90%) because it is utilised for respiration and metabolic processes.

Food Web

A food web is the complete network of interconnected food chains within an ecosystem, illustrating the various routes energy and nutrients can take.

• Connected Chains: Multiple food chains overlap and intersect with one another.

• Biodiversity: Identifies the feeding diversity of relationships and dependencies among different organisms.

• Stability: The stability of the ecosystem is shown by giving alternative feeding options to organisms.

Human Impact on Ecosystems

Pollution, whether it be in the air, water, or soil, pertains to the inclusion of deleterious elements into an ecosystem, hence changing the natural self-proceeding and therefore affecting biodiversity. Air pollution through emissions gives rise to acid rain, while water pollution contaminates aquatic environments and soil pollution causes the degradation of land quality. These pollutants harm organisms and disrupt the food chains and functions of ecosystems.

Deforestation from logging and agriculture is followed by habitat loss and changes in diversity. It also causes soil erosion as a result. Climate change, on the other hand, results in an increase in the level of CO2 in the atmosphere. Rising temperatures, resulting from climate change, alter species distribution and disrupts ecosystem health. The mitigation approaches are by reducing the emission of greenhouse gases through renewable energy sources.

Conservation Efforts

Conservation may involve the creation of protected areas, say national parks, and maintenance of biodiversity through sustainable agriculture, forestry, and sea fishing. On the other hand, restoration ecology targets rehabilitating degraded ecosystems to almost their natural state to ensure that there is enrichment of biodiversity and improvement in ecosystems that provide services. This helps to reduce the impact of a human and ensures the health of the ecosystem.

Tips, Tricks, and Strategies to Prepare for Ecosystems

Here are some tips, tricks and strategies to prepare for ecosystems:

Mnemonics

Use the sentence T-A-M to remember the biomes of ecosystems: Terrestrial, Aquatic, and Marine.

Study Aids

Create sketches showing biotic and abiotic components in several different types of ecosystems.

Compare the features that describe characteristics of different types of ecosystems using tables or charts, and include examples that demonstrate these features.

Multimedia

Watch videos or animations of how ecosystems function such as food chains and ecological interactions.

Take virtual tours of biogeochemical cycles to see nutrient flux.

Flashcards

Flashcards will help to memorize such definitions as ecosystem, biotic components, and abiotic components, along with examples of specific ecosystems.

NCERT Solutions Subject-wise link:

• NCERT solutions for class 12 Physics
• NCERT solutions for class 12 Chemistry
• NCERT solutions for class 12 Mathematics
• NCERT solutions for class 12 Biology

Types of Questions and Weightage of Ecosystems in Exams

The table below indicates the types of questions asked from Ecosystem in Various Exams:

NCERT Exemplar Solutions Subject-wise link:

• NCERT exemplar solutions for class 12 Physics
• NCERT exemplar solutions for class 12 Chemistry
• NCERT exemplar solutions for class 12 Mathematics
• NCERT exemplar solutions for class 12 Biology

Prescribed Books for Ecosystems

NCERT Biology textbook class 12 forms the base for learning the Ecosystems concept. Further extended understanding of the concept can be done through "Trueman's Elementary Biology, Volume 2", which provides all essential explanations with practice questions. Another helpful book is "Pradeep's Biology" which provides proper explanations with solved examples. Other great videos, articles, and practice mock tests are available on the Careers360 website for this topic.

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