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The term “ecosystem” is derived from the Greek word “Oikos” meaning.

3. House

The function of an ecosystem is related to the cycling of materials (matter) and flow of energy.

Types of functions:

Functions of an ecosystem are of three types:

1. Primary Function: The producers (plants) can make their food themselves through photosynthesis. This process is called primary function of eco system. Examples: All green plants and trees.

2. Secondary Function: The consumers (animals and humans) cannot make their own food. They are always depending upon the producers for their energy. This is called secondary function of eco system.

3. Tertiary Function: Decomposers attack the dead bodies of consumers and producers and decompose them into simpler compounds. During the decomposition inorganic nutrients are released. Examples: Micro organisms like bacteria and fungi, etc

The functioning of an ecosystem may be understood by studying the following terms:

A. Food chains

B. Food webs

C. Food pyramids (or) Energy pyramids

D. Energy and material flow.

The term structure refers to various components. So, the structure of an ecosystem explains the relationship between the abiotic (non-living) and the biotic (living) components.

Each and every ecosystem has two major components are:

1.Biotic (living) components.

2. Abiotic (Non-living) components

Biotic Components: The living component of an ecosystem is called “Biotic component”. Examples: Plants (Producers) ,Animals (Consumers) and Micro Organisms (Decomposers) The biotic components of an ecosystem are classified into three types based on how they get their food.

A. Producers (Autotrophs) : Plants

B. Consumers (Heterotrophs) : Animals

C. Decomposers (Saprotrophs) : Micro organisms

A. Producers (or) Autotrophs (Auto=self, troph=feeder) The sun which is the primary source of energy, gives energy to the plants to produce food through photosynthesis. Plants use the light, carbon dioxide, water and the green pigment chlorophyll in their leaves to produce sugars and oxygen. These plants that produce food through photosynthesis are called producers. They are autotrophic organisms because they manufacture their own food. Producers are called energy transducers.

B. Consumers (or) Heterotrophs (Hetero = other, troph = feeder: Consumers are organisms, which cannot prepare their own food and depend directly (or) indirectly on the producers.

Examples: Plant Eating Species: Insects, rabbit, goat, deer, cow, etc. Animals Eating Species: Fish, lions, tigers, etc.

Depending upon the food habits the consumers are divided into four types.

i. Herbivores (or) Primary Consumers (Plant Eaters)

ii. Carnivores (or) Secondary Consumers (Meat Eaters) 

iii. Omnivores (or) Tertiary Consumers (With plant & meat eaters) 

iv. Detritivores (dead organism eaters)

Herbivores: Animals that eat only plants are called Herbivores. They directly depend on the plants for their food. So they are called Plant eaters.

Examples: Insects, goat, deer, cow, horse, etc.

Carnivores: Animals that eat other animals are called carnivores. They directly depend on the herbivores for their food.

Examples: Frog, cat, snake & foxes, etc.

Omnivores: Animals that eat both plants and animals are called omnivores. They depend on both herbivores and carnivores for their food.

Examples: humans, tigers, lions, rats and fox etc.

Detritivores: Animals that eat dead organisms and waste of living are called detritivores.

Examples: beetles, termites, ants, crabs, earthworms, etc.

C. Decomposers (or) Saptrotrophs: (Sapros = Rotten, trophos = feeder) Decomposers attack the dead bodies of producers and consumers and decompose them into simple compounds. During the decomposition inorganic nutrients are released. The organisms which break down the complex compounds into simple products are called decomposers (or) reducers.

Examples: micro-organisms such as bacteria and fungi, etc.

2. Abiotic Components: The non-living component of an ecosystem is called “abiotic component” .

These non-living components enter the body of living organism, take part in metabolic activities and then return to the environment. The abiotic component of the ecosystems divided into three portions.

1. Climate factors : Solar radiation, temperature, wind, water current, rainfall, etc.

2. Physical factors : light, fire, soil, air, etc.

3. Chemical factors : Organic and Inorganic substances.

The huge tree can be an independent ecosystem. On one such tree there may be different habitats. Variety of insects thrive on huge tree by making their habitats in cracks and crevices on the tree. Many birds visit the tree to feed on such insects. There are many bird species that live in the hollow of the tree. Garden lizards, chameleons, snakes are the different reptiles seen associated with the tree ecosystem.

Squirrels, rabbits, bats are the mammals which take shelter in and around the trees, also inhabit a tree variety of fungi, lichens, mosses and epiphytic plants like orchids survive on the huge trees. Many food chains and complicated food webs are formed with the support of the tree. Thus one can say that a tree is an independent ecosystem.

The structure which is formed due to interactions between abiotic and biotic factors is called an ecosystem.

(i) Longer summer and limited rain develop dwarf plants in the grassland ecosystem.

(ii) 71 % of the earth surface is covered by water and only 29 % has land on it.

(iii) Dams lessen the water current in lower area.

All plants produce food through photosynthesis and are categorised as self food producers i.e. these are autotrophs. There are plant eating animals called herbivores as Rabbits, deers, pigeons, cows, buffaloes etc. and insects like grasshoppers, bees, butterflies and crickets also eat plants or plant products as fruits, flowers, pollen grains and plant juices. Such animals are called primary consumers. Animals like tigers, lions, wolves, lizards, frogs eat the primary consumers. Birds vultures, kites, eagles eat the primary consumer, (i.e. These birds are well eat the flesh of many birds like pigeons, sparrows.) These animals or birds are called secondary consumers. 

Animals like snakes are eaten by the peacocks, they eat the secondary consumers and are called tertiary consumers. Owls, eagle are top carnivore. So it is quaternary consumer.

(i) Primary, secondary, tertiary consumers are the biotic factors of the ecosystem.

(ii) Most of the ecosystems are complex.

(iii) The word ecosystem was brought in the use by A.G. Tansle.

(iv) Specific ecosystem developed in a vast area is called a biomes.

(a) Snakes are primary consumers (F)  No the snakes are not primary consumers as snakes eat rats and frogs as these are  primary consumers which eat plant products. As snakes eat the primary consumers so  the snakes are secondary consumers.

(b) Some humans are strictly primary consumers and some others are of other  types of consumers also (T)  It is true that humans are vegetarians and eat plants or plant products. So these  humans are vegetariBut there are certain humans which eat the flesh or eggs of other  animals. These are carnivores and humans living plants are called Herbivores.  

(c) No ecosystem can survive without light (T)  The plants and animals and micro-organisms present at a place and interacting with the  atmosphere like sun light, air, water, soil and warmth and dwelling at a place like, pond,  desert, forest, rock form the ecosystem as pond ecosystem, desert ecosystem forest  ecosystem. So ecosystem cannot survive without the presence of light. As the flora  (plants) living in that ecosystem can only make food in the presence of light and the  animals (Fauna) living in that ecosystem get the food from the plants of that ecosystem.  So flora in that area cannot survive in that area without light and animals living in that  area will not get the food and the plants and animals will perish and the ecosystem  cannot survive.  

(d) Cattle go to ponds for drinking water, so they are a constituent of pond  ecosystem (F)  Cattles likes tigers, lions, cows, deers, buffaloes, go to take water from the pond and  return to their dwellings as tigers, deers etc. come to the forest so they form a forest  ecosystem. But plants like hydrilla, vallineria, lotus etc. and animals like frogs, beetles,  fish live in the pond and form the pond ecosystem. But animals like buffalo which come  only to take~water cannot form a part of the pond ecosystem.

Ecosystem is the structure formed by the interrelationships between the living organisms and non-living components in their surrounding habitats. Living organisms are also called biotic factors while the non-living components are called abiotic factors. The abiotic and biotic factors have a reciprocal relationship with each other. The ecosystem has plants as producers, animals as consumers and microbes as decomposers.

The decomposers return the substances back to the nature by process of decomposition in which the organic complex molecules are reduced to their inorganic constituents. Thus the dead remains of plants and animals are once again recycled back to the nature in any healthy ecosystem.

Food Web:

• Web means “network” . So, food web is a network of food chains. 
• In a food web many food chains are inter connected, where different types of organisms are connected at different tropic levels. 
• So,food web is the natural interconnection of food chains and a graphical representation of what-eats-what in an ecological community. 
• Another name for food web is consumer-resource system.

This food web shows many linear food chains . These linear food chains are inter connected with other food chains operating in the eco system to form a food web. The grazing food chains are as follows:

The complex feeding relationships form a food web. In nature in any ecosystem, the food chains are not straight and linear. But these are quite complex. A prey is consumed by a predator but this predator can itself be a prey to some other predator. E.g. Frog is a predator for variety of insects but frog is preyed upon by snake and the snake can be eaten by a bird. The same bird can also feed on insects or frog. The interrelationships between different biotic components of any ecosystem thus form the complicated food web.

Biomes are a larger collection of small ecosystems which are similar in their structure. In a particular biome there are same climatic, abiotic factors and similar living organisms. Biomes are of two main types, land biomes and aquatic biomes. The land biomes exist only on land. Land biomes are of following subtypes based on the abiotic factors. E.g. Grasslands, evergreen forests, deserts, Tundra ecosystem, ecosystems in Taiga, tropical rainforests, etc. Aquatic biomes include freshwater ecosystem, marine ecosystem and brackish water ecosystem found in the creeks.

Correct option is (d) Desert

Earth’s 71 % of surface is covered over by aquatic ecosystems. They are of three main types, viz. fresh water ecosystem, marine ecosystem and brackish water ecosystem. Rivers, lakes and ponds and streams are some of the fresh water ecosystem. Fresh water contains less salt and hence it is potable. Marine water has more salinity, i.e. its salt content is high. Brackish water ecosystem is present in the creeks. Here the saline and fresh water mix together.

Hence salinity here is lesser than that of the marine water.

Are cut down causing deforestation. The wild animals lose their habitat. Many of them become extinct. There is great loss of flora and fauna due to construction of large dams. There is undue pressure on the land surface caused due to stored water column. This may cause earthquakes. The human settlements are removed as their houses and farms are immersed under water. In all the above ways large dams destroy the ecosystems.

(a) Grass → Grasshopper → Frog → Snake

(b) Grass → Deer → Tiger

(c) Wheat → Rat → Snake → Peacock

(i) Biotic community is another name Biotic for ecosystem.

(ii) Microbes in an ecosystem are decomposers.

(iii) Many types of ecosystems are found in biosphere.

(iv) Taiga is a type of grassland ecosystem.

(v) Gir forest in Gujarat is the only habitat shelter for the spectacular Asiatic lion.

Man tries to use grasslands for agricultural purpose. This transformation causes loss of natural ecosystem. Many animals from grasslands are killed by hunting and poaching. Though now Wildlife Act has protected these animals, many wildlife species are already extinct. There are chances of forest fires which is the greatest threat to grasslands. The global warming may also cause grasslands to become a desert.

When British ruled India, Asian Cheetah was hunted to a great extent. The kings and British rulers did rampant hunting. The forest lands were also reduced due to encroachment by humans to build their settlements. Dams were constructed. Mega highways, bridges and roads caused loss of habitat for Asian Cheetah. Cheetah needs large thickly forested territory. This was lost due to all man-made activities. All these reasons made Asian Cheetah extinct in last century.

Microbes play the role of decomposers in the above interactions.

Consumers get their food from producers and other consumers.

Cheetah is the fastest running feline animal on the earth. Though from Asian regions it is said to be extinct, in African grasslands, its occurrence is still there. But it is endangered animal. By 2016, the global cheetah population is estimated at approximately 7,100 individuals in the wild. Several African countries have taken steps to improve cheetah conservation measures.

Cheetah has a slender body, deep chest, spotted coat. Its head is small rounded and on the face there is black tear-like streaks. It has long thin legs and a long spotted tail. Cheetah in India were tamed during Moghul period for assisting in hunting. Stories about such episodes are commonly told. 

However, the last Cheetah in India was spotted in Bastar, M.P. in 1948.

Producers obtain solar energy from sunlight. The other nutrients are obtained from soil, water and air.

In our surroundings there are abiotic and biotic factors. The biotic factors are animals and plants in the surroundings. The invisible bacteria and fungi also have important role in the ecosystem as decomposers. Important abiotic factors are air, water, land, sunlight, etc.

We are directly or indirectly connected to every single factor in the surrounding in which we reside. For the requirement of food, we are dependent on plants and animals. For our survival we continuously need oxygen, water and other minerals, etc.

The picture no. 1 is showing desert ecosystem, while the picture no. 2 is showing a forest ecosystem where a wetland (a lake) is also shown. In desert ecosystem, the producers are green cactus and a palm tree. Since in desert there are scanty rains, the vegetation is very less. The soil is sandy soil. The consumers of the desert are also limited.

In the above picture camel is shown which is a primary consumer in the desert ecosystem. Camel is very well adapted for desert life. There is also the scarcity of water in desert and hence cactus shows xerophytic (suitable to survive in desert) adaptations.

In second picture, the forest ecosystem is shown because we can see elephant and tiger in the picture. Also, giant hornbill is sitting on the tree. This forest must be tropical evergreen forest. The rainfall is heavy in such areas and hence different types of wetlands can be seen in forests. Wetlands support variety of life. A separate aquatic ecosystem does exist here which is closely interconnected with the terrestrial ecosystems through food chains and food web.

The birds utilize the fish as their prey. The wild animals come to wetlands to quench their thirst. In this picture the plants, grass, etc. are producers, small fishes in the lake are primary consumers. They will be eaten by larger fishes which are secondary consumer in the aquatic ecosystem. The elephant is herbivorous animal and hence it is primary consumer. Snake is the secondary consumer while the birds of prey (eagle that is flying) and tiger are tertiary consumers.

(i) Air, water, minerals, soil are physical factors of an ecosystem.

(ii) River, ponds, ocean are aquatic ecosystems.

(iii) Man is consumer in an ecosystem.

(i) Dipterocarpus. (All others are aquatic plants.)

(ii) Parthenium. (All others are forest trees.)

(iii) Cheetah.. (All others are surviving grassland animals, Cheetah is a forest animal that is extinct from Asia.)

Honey bees provide us with honey and bee-wax. Both of these are commercial products. But more than that the role played by honey bees in the pollination of flowers is very important. Due to their nectar collecting behaviour, they bring about pollination of the flowers.

Presence of honey bees is thus very essential for the agriculture and horticulture. Without honey bees, the growth of fruits and grains will not be possible, if pollination and subsequent fertilization does not take place in nature. This will create famine-like conditions. Therefore, honey bees’ position in the nature is very important.

Correct option is (b) Ambient temperature

(i) Hyena. (All others are primary consumers, Hyena is tertiary consumer.)

(ii) Leptocorsia. (All others are decomposers, Leptocorsia is primary consumer.)

Decomposition is the process in which the organic compounds are broken down to their inorganic constituents. The organic substances such as carbohydrates, proteins and lipids which are locked in the dead remains of plants and animals are converted into hydrogen, oxygen, calcium, iron, sodium, potassium, etc. by microbes. Therefore, microbes are called decomposers.

Correct option is (c) Salinity

(i) Animals

(ii) Kite/Lion/Hyena

(iii) Forest ecosystem

(iv) Aquatic biome

(v) Excessive rain.

Correct option is (a) Humidity

Correct option is (b) Creek water is less salty than the river water.

Flora: Plants occurring in a particular is called flora of that area i.e. vegetative growth  forms flora. Flora deals with plants. 

Fauna: The animals occurring in a area form the  fauna of that area.  Fauna deals with animals.  Flora and fauna of an area is the plants and animals found in that area.

The aquatic flora (plants) and fauna (animals) are well adapted to their habitats. The running water ecosystems are known as lotic ecosystems. The nonmoving waters on the contrary create lentic ecosystems. Lotic ecosystems provide special adaptations to the plants and animals living therein. Plants are mostly in the form of freely floating algae and phytoplankton. Animals are well adapted for swimming in the currents of water. The fishes especially show a stream-lined body, fins for swimming, and gills to take up dissolved oxygen in the water. The other animals are also well adapted to the currents of water.

The biotic factors include plants, animals and humans. Lot of vegetation is submerged from the place where dam is constructed. The forests are wiped out. Large scale deforestation takes place in the proposed dam area. Wildlife is destroyed completely. The resident animals whose habitat are there either migrate away or are killed due to lack of their food and shelter. Many instances of animalhuman conflicts arise when the wild animals drift to the neighbouring human settlements.

If human settlements are shifted, people are displaced. They lose their houses and agricultural land. Though compensation is given to them, there is great change for the people. Water current in lower area of the dam is reduced due to construction of dam-walls. Therefore, the original lotic (running 5 water) ecosystems that were present are destroyed after the construction of dam.

(a) Symbiosis: It refers to relationships between organisms of different species that  show on intimate association with each other. Symbiotic relationships provide atleast  one of the participating species with a nutritional advantage.  Examples of Symbiosis Relationships are of Fungus and photosynthestic alga and  Microbes and cattle.  

(b) Parasitism: Parasitism is a type of symbiotic relationship between organisms of  different species where one organism, the parasite, benefits at the expense of the other,  the host. Examples of Parasitism are 4 tapeworms, flukes, the plasmodium species and  mosquitoes.  

(c) Predation: A predator is any consumer that kills and eats another living organism in  order to obtain energy. The organism being eaten is called the prey.  Examples are Lions, Deer, Wolves, Eagles.

1. The abiotic factors such as air, water, soil, sunlight, temperature, humidity, etc. affect the biotic factors, i.e. the surviving plants, animals and microbes in the ecosystem. 

2. The type of abiotic factors in an ecosystem determine the survival of biotic factors. The population of these biotic factors is also dependent on the quality of abiotic factors. 

3. The proportion of abiotic factors in an ecosystem fluctuates as biotic factors use up or release particular abiotic factors. 

4. Every biotic factor also interacts with its necessary abiotic factors as well as other biotic factors around it.

The position of any living organism with reference to other living organisms and the role played by that organism is called ecological niche.

Grasslands, evergreen forests, deserts, Tundra or polar ecosystem, ecosystems in Taiga, tropical rainforests, etc. are land biomes.