Ecology Notes For All Competitive Examination UPSC, PCS, SSC

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 Ecology Notes For All Competitive Examination:-
Ecology Notes For All Competitive Examination:-

 Ecology Notes For All Competitive Examination:-

The word Ecology has been made from two words-Oikas (living place) and logos (study), which impulses that Ecology means the study of the living place. Letter Haeckel defined it as below-

The branch of Biology under which organisms (living beings) and their mutual relationship with surroundings (atmosphere) are studied is called Ecology.

Broadly Ecology can be divided into the two groups-Autoecology and Synecology.


The branch of Ecology in which only one type of species of the organisms is studied.


The branch of Ecology in which the entire community of the organisms of any specific region is studied.

Ecological factors:

The factors of environment, which directly or indirectly interact with organisms (living beings) are called ecological factors. These are of two types-

A. Abiotic factors:

Under it, non-loving factors come into existence and the main abiotic factors are-

1. Light: The plants prepare their own food by the process of photosynthesis in the presence of light. The creatures directly depend on the plants for the food. Some other activities like locomotion activities in plants, seed sprouting, respiration, evaporation etc. are also affected by the light.

2. Temperature: The temperature directly affects the physiology of the organisms and their activities like reproduction etc. Also along with the alternation of the temperature, the day to day activities of the plants change. For the biotic activity, the average required temperature is 10-degree Celsius to 45-degree Celsius. The temperature dependent activities in the plants are called Photoperiodism and on increasing the temperature the rate of evaporation increases and vice-versa.

 Ecology Notes For All Competitive Examination:-

3. Humidity: Due to the presence of water-vapour the atmospheric air remains moist and humidity is directly related to the evaporation. If the humidity is low then evaporation is high and vice-versa.

4. Wind: The wid directly imparts its effect mainly in soil erosion, bending of plants, in pollination and in the scattering of the seeds etc.

5. Topographic: Topographical factors like the expansion of land, mountains, altitude, latitude etc affect the organisms too

6. Edaphic: Almost all vegetations directly interact with soil structure, soil-wind, soil-water etc.

7. Availability of food-stuffs: The availability of food-stuffs of various organisms has a direct relationship with their dwellings. It is generally observed that organisms reside those places where food-stuffs are easily available and adversely where these availabilities are not easy, they reside there in fewer number.

Ecology Notes For All Competitive Examination:-

B. Biotic factors: 

Biotic factors affect much more the organisms and various types of organisms have a better interaction with each other. These interactions are of various types given as below-

1.Symbiosis: In it, two organisms mutually interact positively and form another organism. The fungi and algae mutually interact and form Lichen which is an example of symbiosis.

2. Parasitism: Some organisms always depend on other especially for the nourishment and called parasite and dependents always damage the other. The fungi, bacteria, viruses etc are various parasitic microorganisms.

3. Commensalism: In this relation, organisms interact mutually in such a way that no loss or gain takes place between the organisms and up to some extent they mutually assist to each other. The example of this relation is Epiphytes.

4. Saprophytism: Some organisms depend on rotten substances especially for their nourishment. The microorganisms like fungi, erotic etc. are saprophytes.

Ecological succession:

The establishment of an ecological community in a specific region is called ecological succession. After the establishment of an ecological community at any specific place the process of evolution in it continues and on the basis of development, there are two types of ecological succession-

  1. Primary succession: When an ecological community is developed in the regions, where no ecological community was earlier found to be developed is then it called primary succession. The examples of this succession are sandy land, rocks of stone etc.

2. Secondary succession: When an ecological community is developed in the regions, where the ecological community was earlier present but whose existence has been destroyed is called secondary succession. The example of this succession is to destroy a forest through the fire but again reappearance ad development of a new forest community.


The word Ecosystem was firstly pronounced and used by Tansley in 1935. The mutual relationship of an organism with surroundings and another organism among the organisms of any particular place is called Ecosystem. This is of two types-

  1. Natural ecosystem: The ecosystem which exists naturally like forests, deserts, ponds, tundras etc form a natural ecosystem.
  2. Artificial ecosystem: The ma made ecosystem like gardens, crops, parks etc form an artificial ecosystem.

  Ecology Notes For All Competitive Examination:-

Components of Ecosystem: There are two components of the Ecosystem and these are-

  1. Biotic components: The plants and creatures form abiotic component and it is of three types-

A. Producer: The biotic component which prepares its own food comes under the category of producer and the ratio of carbon dioxide and Oxygen is also maintained up to a fixed proportion to remain the ecosystem intact. Almost all green plants are examples of a producer.

B. Consumer: The biotic component which consumes or utilizes the food prepared by the producer is called the consumer and it is of three types:

a. Primary consumers: Under it, those creatures come who consume green plants or their any part are called primary consumers. The animals’ like a cow, buffalo, goat etc are primary consumers.

b. Secondary consumers: Under it those creatures come who consume the primary consumers in the form of food like cat, sheep, peacock etc are called secondary consumers.

c. Tertiary consumers: Under it, those creatures come who consume the secondary consumers in the form of food, called tertiary consumers.

The animals like tiger, lion, leopard etc are tertiary consumers.

C. Decomposers: Under it, bacteria and fungi come which are frequent and main decomposers of almost all consumers and producers and diffuse them in the form of inorganic elements in the atmosphere. These decomposed residues easily mix up in the physical environment, consequently, green plants absorb these residues which are transformed into food. Again these green plants are consumed by the primary consumers and the cycle is continued.

 Ecology Notes For All Competitive Examination:-

2. Abiotic components: Under it, organic substances, inorganic substances, water, temperature, light etc have been kept.

Ecological classification of plants: E. Warming classified ecologically the plants into five groups given as below-

A. Hydrophytes

B. Mesophytes

C. Geophytes

D. Plants of Physical dryness in the soil

E. Plants of active dryness in the soil.

Speciality in plants:

Eremophytes-               The plants growing in dessert or step.

Lithophytes-                  The plants growing on the rocks.

Psammophytes-             The plants growing in the sand.

Sclerophytes-                Woods bush plants.

Halophytes-                   The plants growing in the soil of more concentration.

Oxylophytes-                  The plants growing in acidic soil.

Helophytes-                    The plants growing in the swamp.


The occurrence of unwanted physical, chemical and biotic changes which generally cause an imbalance in our ecology or environment through the air, land or water is called environmental pollution. The pollution may be either natural or artificial (man-made). The substances or factors through which changes occur are called pollutants generally pollutants have been divided into two groups-

Biodegradable pollutants: The pollutants of this group are decomposed by various microorganisms like bacteria, fungi etc. and the decomposed substance enters into a bio-geo-chemical cycle. These decomposed substances become the part of pollution (pollutants), whenever such substances are excessively produced then these are not absorbed. A various substance like residues of domestic kitchen, Faeces (stools) and urine, agricultural residues in the form of by-product paper, wood, clothes etc. are the examples of biodegradable pollutants. Non-biodegradable pollutants: The pollutants of this group do not decompose (reduce) into the simpler products and these pollutants are generally toxics and enter into the chain of food of the organisms and pose them. The substances like DDT, pesticide, insecticide, mercury, lead, arsenic, aluminium, plastic, radioactive substances, wastes etc are examples of non-biodegradable pollutants.

Types of pollution: On the basis of the pollution spread various types of pollution of our environment can be classified in the following groups- air pollution, water pollution, sound pollution and radiation (radioactive) pollution.

A. Air pollution: The air is basically a mixture of oxygen, nitrogen, carbon dioxide etc and these gases have a definite ratio and the occurrence of imbalance in their ratio produces air pollution.


The source of pollution can be classified into two groups-

  1. Natural source: The natural source of air pollution are a forest fire, ashes of a volcano, dessert sandy storm, decomposition of an organic substance, flying pollen grains in air etc.

  2. Artificial (man-made) source: Various components like population explosion, deforestation, urbanization, industrialization etc. are the artificial (man-made) source of air pollution. Also through various human activities like man-made gases-carbon monoxide, sulfur dioxide, hydrocarbon, nitrogenous oxides and some others like lead, arsenic, asbestos, dust particles, radioactive substances etc. are major air pollutants which spread air pollution rapidly.

    Losses through air pollution:

    a. The presence of a larger amount of carbon monoxide in air causes, harassment, irritation, headache, chronic mental sickness, uncomfortable surrounding etc. The haemoglobin of the blood directly reacts with carbon monoxide and forms a complex carboxy1 haemoglobin stable compound, which is deadly poisonous (toxic). In human beings, it causes too much suffocation and in few cases sometimes demise (death) occurs.

    b. Ultraviolet rays are appearing on the earth’s surface in an excess amount due to the depletion of the ozone layer. The human eyes and their immune system can damage through ultraviolet rays and even skin cancer may have happened through it especially to white people. Indirectly it causes global acid rain, ecological imbalance non-availability of the global edible oils etc.

    c. Acid rain is caused by air pollution and it appears in the presence of nitrogen and sulfur dioxide which are damaging the historical monument, buildings, idols etc. The acid rain makes the soil acidic and fertility of the soil start to spoil which adversely affects the agricultural productivities.

    d. through the smoke emission pipe of the motor vehicles free lead releases in the open atmospheric air which causes disease like anthrax, eczema etc. in the human beings.

    e. Some pesticides also produce pollution by entering inside the food chain of the organisms and increase their concentration in the organisms. This process is called Bio-magnification and because of it in kidney, brain and in the circulatory system various types of disorders (defects) appear.

    f. Arsenic makes the plants poisonous which causes the animals death on eating the plants.

    g. Fossil fuels (coal, petroleum etc) When brunt then carbon dioxide and methane gases are produced and they prevent the thermal radiations emitting from the earth’s surface to go outside from the atmosphere. Thus the temperature of the earth increases and consequently the weather abruptly changes and sea level also increases. Thus a substantial increase in temperature may cause to melt the glaciers and ice floated peaks and a devastating flood may appear.

    h. The emergent sulfur dioxide gas from the outlets of factories may produce severe pain in the respiratory tracks and can damage the lungs of human beings.

    Chloro Floro Carbon (CFC) is the chief depleter of the ozone layer which is released from the fire extinguisher, refrigerator, and aerosols.

     Ecology Notes For All Competitive Examination:-

    Greenhouse effect: The emergent gases like carbon dioxide, carbon monoxide sulfur dioxide etc. by various artificial processes pollute the atmospheric air and prevent the infrared rays (thermal radiations) reflected from the earth’s surface and thus an abrupt increase in temperature takes place. This defect is called greenhouse effect.

    B. Water pollution: When the certain physical, chemical and biotic change take place in the water in such a way which make the water toxic and becomes unuseful for the organisms (living beings) then it is called water pollution.

    Source: The sources of pollution can be classified into two groups-

    1. Point source: The powerhouse, underground coal mines, oils well etc confined and located near the water source are the examples of point sources. Such type of sources directly supply the pollutants to the water.

    2. Non-Point source: Such type of sources are scattered at various places and in the water from one point or from a definite place it doesn’t flow. The water flowing from fields, gardens, construction places, road and streets etc come under non-point sources.

    Water pollutants: Various compounds of calcium and magnesium and some other substances are dissolved in the natural sources of water and make the water impure. Some microorganisms like protozoa, bacteria, and other microbes also pollute the water. The oil in water, heavy metals, d.5etergents, domestic wastes, radioactive wastes etc come under the category of the water pollutants.

    Losses through water pollution:

    1. The disease like Typhoid, Cholera, Hepatitis, jaundice etc. spread due to water pollution.
    2. The acid and alkali present in the water can destroy microorganism and in it, self-purification process of the water of rivers is also disrupted.
    3. The mercury, arsenic, and lead present in the polluted water exhibit the toxic activities for the organisms (living beings).
    4. Exterior flowing excreta (faeces) or stools mixes with water promotes the growth of the algae and it spreads on the surface of the water. Whenever algae die these start to decompose and there exists the deficiency of oxygen in the water, consequently aquatic creatures begin to die.

    5. The pollutants chromium and cadmium are the main components of the marine water pollution and sometimes marine organisms (living beings) die.

      C. Sound pollution:

      The unwanted loud voices or noises listened all around the surroundings by the human beings from the sound pollution.

      Source: The chief source of the sound pollution is loudness or sharp noises, whatever be the process of generation, it doesn’t matter. There are so many examples like cooler, scooter, TV, car, train, rocket, domestic equipment, aircrafts, loudspeaker, washing machine etc. are the sources musical instruments, like from guitar, harmonium etc. which are sweeter and joyful for the heart, mind, and soul are not the part of sound pollution.

      Lesses through sound pollution:

      1. A longer duration of loudness or noise may adversely affect the audibility ability and sometimes human beings may become deaf.
      2. Sometimes too noisy voices cause the activities like irritation, ill- temperateness, headache, sleeping disorder etc.
      3. Also due to the sharp loudness blood pressure and heartbeat of the human bodies abruptly increase.
      4. Sound pollution sometimes causes accumulation of cholesterol inside the arteries and consequently blood pressure increases. Thus ill-temperateness, anger, frustration, excitement etc. appear. If human beings remain in the sharp loudness for a longer duration then laziness and stupid come into existence.

      5. Also, a sharper loudness causes the secretion of the hormone adrenal which becomes more frequent.
      6. The reproductive and metabolic activities are adversely affected if human beings continuously remain in a loud sound for a longer duration.
      7. Sound pollution causes feeble sense organs and nervous system.

         Ecology Notes For All Competitive Examination:-

        D. Soil pollution:

        The deformed structure of the land of soil which is mainly caused by solid waste substances is called soil pollution. The solid (waste) substances usually come from homes, animal houses, industries, agriculture and from some other places. The heap of these waste substances comprises ashes, glasses, the residues of fruits and green vegetables, paper, cloths, plastic, rubber, leather, bricks, sands, metals, residues of animal houses etc. Also, various chemicals like compounds of sulfur and lead spread in the air are appeared on the land and mixed up with soil and the soil is polluted. Also to enhance (increase) the soil fertility, various types of pesticides, insecticides, germicides etc. are utilized and these chemical substances collectively pollute the soil. These chemical substances adversely affect the fertility of the soil slowly and steadily and enter into the food chain of almost all organisms.

        The heap of solid wastes not only deforms the natural beauty of the ecosystem but also damages our surroundings. Also, pigs, dogs, rats, flies, mosquitoes etc frequently and randomly move and spread bad smell through these heap of wastes. Non-biodegradable wastes disrupt the water supply and contaminate the water up to some extent and it becomes the ultimate destination of the reproductive activities of the mosquitoes and flies. The mosquitoes are the vectors of various diseases like Dengue, Malaria, Kalazar etc which usually reside in the polluted water.

         Ecology Notes For All Competitive Examination:-

        E. Radioactive pollution:

        The radiative or radioactive pollution mainly causes by the radioactive rays x-rays etc also by the ultraviolet radiations of the sun which are too much harm to the living beings (organisms).

        Source: There are various sources of radiative pollution-

        1. The pollution obtained from the rays used in medical science.
        2. The pollution produced from the fuels used in the nuclear furnaces.
        3. pollution produced from the residues of the nuclear powerhouses.
        4. The pollution produced by the radioactive substances involved in the research and development activities.
        5. The pollution produced through the fission of the radioactive substances present on the earth’s surface, ultraviolet rays coming from the sun, cosmic rays coming from space etc.

        Losses through radioactive pollution:

        1. By the effect of radioactive pollution, mutation takes place in the genes of the germinal cells of the organisms and due to its deformed, stupid and handicapped offsprings born.

        2. Due to the radioactive radiations, the immune system of the human body damages up to a large extent and the human body becomes the disease prone and any disease may easily enter inside the body.

        3. Through the radiative pollution the diseases like leukaemia and bone cancer etc. appear.
        4. Due to the radiative effect, the reproductive ability of human beings is adversely affected and the old age like situation appears.
        5. Due to the radiative effect on the human bodies skin irritation takes a plane and sometimes the wound appears on the skin. Sometimes pain, irritation swelling in the human organs also appear.

        Pollution controlling measures:

        To control the pollution complex chemical substance should not be supplied to the rivers, ponds, and ditches. The basic norms of gaseous emission from the automobile vehicles should be followed properly so that unwanted smokes should be avoided or minimized. The emergent gases from the outlets of various factories before the emission should be filtered. Also the spraying work of pesticides, germicides, insecticides etc. should be according to a standard norm but deforestation work should be banned and o the extensive level afforestation programme the amount of oxygen in the atmosphere can be abundantly increased and correspondingly emerging carbon dioxide can be regulated.

This is All about Ecology Notes For All Competitive Examination UPSC, PCS, SSC

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