BBA Environmental Studies Questions Unit 3

BBA Environmental Studies Questions Unit 3

BBA Environmental Studies Questions Unit 3

Q.1. Describe structure and functions of ecosystem (2011) 


Classify ecosystem. (2013)

Ans. The term ecosystem was coined by Tinsley (1935). Ecosystem is the structural and functional unit of biosphere, comprising living beings and their non-living environment.

The ecosystem may be temporary (rained pond) or permanent (forest). The size is also variable. It may be like a flowerpot (micro-ecosystem) or ocean (macro-ecosystem).

Structure : The components are of two types

  1. Biotic
  2. Abiotic

(a) Biotic Components : These plants, animals and microbes which are known producers, consumers and decomposers, respectively are known as biotic components.

(i) Producers : These are photo-autographs and chemoautotroph’s.

(ii) Photoautotroph : These are green plants, Euglena, green sulphur bacteria etc. They can perform photosynthesis and prepare food. They dominate terrestrial ecosystem. All animals and human beings are dependent on them for food.

(iii) Chemoautotroph : They are iron, sulphur bacteria which releases energy during chemical reaction and prepares organic food. This process is known as chemosynthesis.

Producers use CO2 and release 02. Hence, maintain CO2 – 02 balance in nature. They also convert radiant energy of sun into Ecosystem : Concept chemical energy and are known as transducers. This process is ecosystem, structure and fun known as transduction. an ecosystem, prod.

(b) Consumers : They are tropospheres and cannot produce food. These are of three types:

(i) Primary Consumers : These are called herbivores and eat ecological succession, too plants and their products e.g. cattle, goat, rabbit, rat, grasshopper (terrestrial ecosystem) and snails, tadpols, tortoise, (aquatic ecosystem) etc.

Elton used the term key industry animals for primary consumers as they convey plant material into animals material.

 (ii) Secondary Consumers : These are called carnivores Aquatic ecosystems which eat herbivores. Cats, dogs, foxes are examples of terrestrial streams, lakes, rivers, ecosystem. Hydra, water bug, frogs, small fish are examples of aquatic ecosystem.

(iii) Quaternary Consumers : These are largest carnivores e.g. lions/tigers on land and whales in aquatic ecosystem, these are also known as top carnivores.

(c) Decomposers (Saprophytes) : These are bacteria/fungi which derive their food from dead plants and animals and their waste products.These are also called micro consumers (reducers) due to their small size. They add inorganic materials to the environment and help in mineralization.

E. coli, Tapeworm etc are parasites or consumers which derive their food from dead plants and animals and their waste products. Some animals like frog is herbivore at tadpole stage and secondary consumer at adult stage. Man, ants, etc. are omnivores. BBA Environmental Studies Questions Unit 3

Insectivorous plants (Drosera) act as producer and consumer. Some animals like termites, vultures feed on dead organisms and are known as scavangers (detrivores).

2. Abiotic Components: These include non-living factors which affect the distribution/structure of organisms. These are as follows:

(a) Inorganic substances like carbon, oxygen, nitrogen, CO2, calcium, phosphorus, sulphur and micro-nutrients etc. which occur in form of compounds dissolved in water, in soil or in free state.

(b) Organic compounds like lipids, proteins, carbohydrate, nucleic acids, vitamins, humid substances on which all living beings are dependent for their sustenance.

(c) Temperature, light, water, gases, wind, humidity, soil, animals etc. are also the part of abiotic components.

Producers : Green plants (herbs, shrubs, trees) photosynthetic bacteria, cyanobacterias, phytoplankton includes the producers.

Macro-consumers: These are of four types. They eat or inject producers directly or indirectly.

Types of ecosystem
Types of ecosystem
Relationship among members of an ecosystem
Relationship among members of an ecosystem
  1. Primary consumers (herbivores)
  2. Rabbit, rat, deer, goat, grasshopper, cattle etc. (terrestrial ecosystem).
  3. Molluscs, Crustacean (Aquatic ecosystem).
  4. Secondary consumers : primary carnivores feed upon herbivores, snake, wild cat, foxes, frogs, centipedes etc.
  5. Tertiary consumers (secondary carnivores)-wolves etc.
  6. Quaternary consumers (tertiary carnivores)-tiger, lion etc.

The decomposers are essential as they secrete enzymes to digest organic compounds externally, help in mineral recycling and cleaning of environment, e.g. bacteria, fungi etc.

Functions of Ecosystem

The functions of ecosystem are :

  1. Production of food by autotrophs, chemo autotrophs.
  2. Use of solar energy by green plants
  3. Recycling of minerals.
  4. Helps in maintaining CO2/02 ratio in atmosphere.
  5. To maintain flow of energy
  6. Ecosystem is a discrete structural, functional and life sustaining environmental system.

Q.2. Describe ecological pyramids. (2013)


Effect of ecological pyramid. (2013)

Ans. Ecological Pyramids: The relationship between the various trophic levels of a food chain can be expressed in terms of number/biomass and energy by graphic diagrams, called ecological pyramids.

These were first divided by C.Elton in 1927 and are called as eltonian pyramids

Fig.(a) Pyramid of biomass (i) upright interstitial ecosystem (ii) inverted in aquatic ecosystem. Fig. (b) Pyramid of number (i) tree; (ii) grassland
Fig.(a) Pyramid of biomass (i) upright interstitial ecosystem (ii) inverted in aquatic ecosystem. Fig. (b) Pyramid of number (i) tree; (ii) grassland

Pyramid of Numbers: It is the graphic representation of the number of individuals or various trophic levels of food chain/unit area at any time. The base is represented by number of producers and apex is represented by the number of top carnivores. The intermediate consumers are placed in between the two depending upon their relationship in food chain. The number of individuals goes on decreasing from base to top.

(c) Pyramid of energ
(c) Pyramid of energy

Pyramid of Biomass : The amound of living material present in an organism is called biomass. In terrestrial ecosystem, biomass of producers is maximum. The biomass of herbiovers is less but their number may be more. The biomass of carnivores shows further decrease toward top. So, the pyramid is always upright.

Pyramid of Energy : It is always upright, producers represent maximum energy content. They obtain energy from sun and manufacture food. Herbivores contain less energy as compared to producers, secondary consumers contain still smaller amount of energy and so on.

There is gradual decrease in energy at successive trophic levels. Energy is maximum at producer level and decreases as one moves to subsequent trophic levels.

Q.3. Write an essay on functional aspect of ecosystems.

Ans. Periodism: In order to discuss vegetational structures, essential and characteristic features were abstracted to a kind of static model. But in this the dynamic, ever changing aspect of physiognomy and compostition is missing. There is a sharp difference between vegetation on the North and South slopes of mountain. The North slope is rather cooler and moist, many herbs are about to bloom or one in bloom or fruit by late spring. The maximum period of herbaceous activity dries and warms south slope is found during early summer. The vegetational difference between the slopes is large due to relative density, frequency and cover and not due to the exclusive presence of slopes in one area and absence in the other. The difference in flowering activity is because of both subtle physiological variations within each species and by subtle but real microclimatological differences between the slopes. Each species has its own characteristic pattern of sequential development and flowering which is attributed to and regulated by the major environmental climatic gradients. BBA Environmental Studies Questions Unit 3

In a deciduous forest, biome spring brings release from dormancy and a resurgence of vegetative activity culminating in leafing out in deciduous trees. Leaf fall brings the onset of dormancy and curtailment of activity manifested in leaf colour change and fall. The natural geophysical phenomenon reach at different intervals and as different species respond differentially to such stimuli, different rhythms would be expected, a prior, among different communities. Photoperiods have major effect on plant behavior. We may observe it as follows:

(a) The regulatory effect of photoperiodism on growth, development and flowering of a single species and there by of the community of which it is a part.

(b) The variation existing within widely distributed species regarding the response to photoperiodism and the conconitant effect on the ecosystem of which they are a part.

(c) The diurnal metabolic pattern of an ecosystem.

Photoperiodism and Ecotypes

The species has a specific physiological response to photoperiodism as it has a specific morphological adaptation to another environmental parameter. Charles Olmsted demonstrated that different population of a common prairie grass known as side-oats grama (Bouteloua curtipendual) did not have indentical response to given photoperiods. Long day plants demonstrate normal vegetative and flowering behaviour only with photoperiods of 14 hours or longer. Short day plants, functions normally under 13 hours of light but failing to bear flower on photoperiods longer than 14 hours. Alpine sorrel (Oxyria digyna) requires 15 hours of light for flowering. There is physiological difference in population at different latitudes. Northern populations have more chlorophyll, higher respiratory rates at the same termperature and an attainment of peak photosynthesis at lower temperature.

The ecological races or ecotypes may show little or no morphological difference.

Photoperiodism and Temperature Effects

On a divernal basis, a number of significant periodic phenomenon affect the function of a community. The desert shrubs are differentially adapted to withstand daily changes of 55°C at the 

The forces in the series of changes involve the changes in density of water with temperature and the action at wind. Because water is most dense at 4°C. warmer and colder water will float on top of a layer at this temperature. After the ice melts the surface water warms to less dense layer immediately beneath it. This overtiming of water in the absence of wind, will occur at 4°C ultimately resunsa temperature that is uniform from top to bottom. Subsequent heating of surface water wonen accompanied by a corresponding decrease in density, results in warmer water at the sunlar. w action results in stirring of the surface water, mixing them to depths according to the sun and direction of wind and relative to exposure or orientation of the system.

Q.5. Describe flow of energy in the living world.

Ans.       Flow of energy in the Living World

The radiant energy that originates in thermonuclear reactions in the sun reaches to earth in the form of light (and other forms of radiation) and sustains all living organisms. Over the entire globe about 25% of the incoming solar radiation is scattered or reflected by the atmosphere back into the back into the space. This fraction of arriving solar radiation is lost to the earth. Another 25% is absorbed by the atmosphere. The remaining 50% that manages to reach the earth surface, some 45% of the total is absorbed as heat by lands or oceans; 5% (of the total) is reflected back into space; 24% 1s consumed in promoting water evaporation and related meteorological (weather) phenomena. A very small fraction drives the winds and waves. An even ‘smaller fraction is captured by the leaves of green plants. Indeed, the total solar energy reaching on earth per year is said to equal1,73,000 X10 watts.

Of this, only 40 x1012 Watts is used in photosynthesis.

It is noteworthy that both the atmosphere and earth surface reflects a significant fraction of the incoming solar radiation. Bare ground and rocks reflect a much larger portion of the incident radiation than green fields and forests, which are more absorbent. Recently satellite engineers have acquired the capacity to estimate on a global scale the total mass of green plants and by inference terrestrial photosynthesis with a high level of resolution. BBA Environmental Studies Questions Unit 3

Distribution of the radiation reaching on earth
Distribution of the radiation reaching on earth
Vertical Zones
  1. Euphoric Zone (Phobic zone): It extends to 200 mts. from the surface. It is a thin zone through which light can pass.
  2. Aphetic Zone : It ranges from 200-2000 mts. and gets less light comparatively but photosynthesis is possible
  3. Abyssal Zone: It is a dark region lying below 2000 mts.
  1. The Littoral Zone: It represents an area from shore to edge of continental shelf. It is euphoric zone.
  2. Benthic Zone: It is formed by continental slope extending into the ocean floor. It includes aphetic and abyssal zone.
  3. The Pelagic Zone : It constitutes the open sea and has variety of flora and fauna. It has euphoric, aphetic and abyssal zone.
Different zone in ocean.
Different zone in ocean.

Q.7. Give an account of food chain and food web.

Ans. Food Chain : It is a serias of populations through which food and energy passes into an ecosystem. The various steps in the passage of food are called trophic levels.


(i) Predator food chain. (ii) Parasite food chain. (iii) Saprophyte food chain

Land Food Chain

 Grass→ cattle + man

Vegetation → bees bear

Vegetation → insect frog → snake → peacock

 Pond Food Chain

Diatomas/algae-zooplankton small crustaceons → insects → fish crocodile kingfisher

Detritus Food Chain

Dead organic matter termites/worms/bacteria (detrivores) → Fungi/Bacteria/Actinomycetes (decomposer)

  1. The food chain is always straight.
  2. Energy flow is unidirectional, i.e. sun producer consumers.
  3. food chain, the successive members are larger in size but lower in number.
Food chain
Food chain

Food Web: A complex of inter-related foodchains is called food web. In nature food chains do not operate in isolation and are interconnected forming a sort of interlocking pattern.

  1. Food webs are never straight.
  2. Food webs are formed by interlocking of food chains.
  3. Food web provides alternative pathways of food availability.
  4. Food webs make ecosystem more stable.
  5. Food webs check over population of organisms.
  6. Also helps in development of ecosystems.
Food Web.
Food Web.

Q.8. Describe the sulphur cycle.

Ans. Sulphur Cycle:   Sulphuris an important part of some amino acids. It is absorbed by plants as suphates. Its main source is earth’s crust.

The sulphur is released back to soil by decomposition. Microbes convert sulphates. sulphates. In marshes under anaerobic conditions, sulphur may be converted to sulphides by bacteria. Sulphides may be oxidized to sulphates. Sulphur may be added to atmosphere as oxides (SO2) due to the burning of fossil fuels or by volcanic activities or smelting of sulphur ores and factories. BBA Environmental Studies Questions Unit 3

Sulphur cycle
Sulphur cycle

Q.9. Describe oxygen cycle.

Ans. Oxygen Cycle Oxygen is an essential element. It is found as O2 in atmosphere and as compounds like H20 and CO2

Utilization : o2 is used by animals for respiration. Oxygen is utilized during combustion and oxidative weathering of rocks.

Release of Oxygen

  1. Oxygen is released during photosynthesis.
  2. Oxygen is released as CO2 during decay of dead organic matter by microbes.
  3. Oxygen and carbon cycles are completely dependent on one another.
  4. Oxygen is converted to 03 (ozone) and protects earth from ultraviolet rays.
Oxygen Cycle
Oxygen Cycle

Q.10. Describe Nitrogen Cycle.

Nitrogen Cycle
Nitrogen Cycle

Nitrogen is an important constituent of proteins, nucleic acids etc.

Nitrogen Fixation: a Largest reservoir of nitrogen (79%) is atmosphere but it cannot be utilized by plants directly unless it is fixed. 150-750. Mg/m2 / nitrogen is usually fixed by Rhizabium, Azotobacter, Clostridium, Anabaena, Tolypothrix. Some amount of nitrogen is fixed by electro-chemical and photochemical methods (35 mg/m2 yr. ) Some nitrogen is fixed by chemical fertilizer factors (Haber’s process).

Uses of Nitrogen : Plants take nitrates from soil. Animals eat plants and proteins are converted into animal proteins. The breakdown of proteins is done into urea, uric acid or ammonium compounds. In soil or water decomposition of wastes takes place and nitrogen is changed to free nitrogen.

Decomposition: It takes place by actinomycetes, ammonifying bacteria, nitrifying bacteria (Nitrosomonas, Nitrobacter) and denitrifying bacteria (Pseudomonas).

Q.11. Describe Water Cycle.

Ans. Water Cycle : Water is an important constituent of living cells. Water may exist in gaseous, liquid or solid state.

In global water cycle, water evaporates from water bodies (oceans, rivers, lakes) and on clouds. The water vapour in clouds cools and condenses to form rain or snow.

The water may fall directly into oceans or may flow to oceans through rivers or underground water. Some water of landmass may seep in as ground water. Some water may remain as perennial snow on mountain peaks or in polar regions.

In smaller cycle, the environmental water moves in living organisms and back to environment. Aquatic animals take water directly and give it back through excretion etc. Land animals take water directly or as food from plants or other animals. In case of plants, water is absorbed by roots and returned to atmosphere through transpiration.

Water Cycle
Water Cycle

Q.12. Define primary and secondary successions.

 Ans. Primary Succession: The primary succession takes place in the barren, soilless uninhabited regions like igneous rock emerged from the sea or a pile of rocks left when a mountain side caves in or areas exposed by a retreating glacier or lake, sand dunes, lava deposites, submerged area. It takes long time usually 1000 years or even more.

Secondary Succession: The secondary succession takes place in the previously inhabited but some how disturbed area burning, grazing, falling of trees, development of industries or roads. It takes less time comparatively, about 50-200 years.

Q.13. Write main differences between primary and secondary succession.

Difference between Primary Succession and Secondary Succession

Q.14. Write main differences between nitrification and denitrification.

Difference between Nitrification and Denitrification

Q.15. Write a short note on “Efforts of eco-development is India”.


Ans. Efforts of Eco-development in India: In Indian context, the exclusivity of Protected Areas (PA), as envisaged in the developed countries is not possible, due to human dominated landscapes in and around them. The population is largely rural that draws on the resources of the PA for subsistence. A participatory management strategy of protected areas, eco-development aims at conserving the bio-diversity by addressing both the impact of local people on the protected areas and the impact of the protected areas on local people. In response to the changed paradigm of partnership, Eco-development Committees (EDCs) emerged around many PAs. The National Afforestation and Eco-Development Board (NAEB), set up in August 1992, is responsible for promoting A forestation and Eco-development committees (NAEB), set up in August 1992, is responsible for promoting afforestation, free planting, ecological restoration and eco-development activities in the country, with special attention to the degraded forest areas and lands adjoining the forest areas, national parks, sanctuaries and other protected areas as well as the ecological fragile areas like the Western Himalayas, Aravallis, Western Ghats etc. The detailed role and functions of the NAEB are given below. BBA Environmental Studies Questions Unit 3

Goal: The goal of the project is conservation of bio-deversity through people’s participation.

Objectives: These are as follows:

  1. To improve capacity of PA management to conserve bio-diversity and increase opportunities for local participation in PA management
  2. To reduce negative impact of local people on biodiversity, reduce negative impact of PA on local people, and increase collaboration of local people in conservation efforts.
  3. To develop more effective and extensive support for community development activities.
  4. Evolve mechanisms for ecological restoration of degraded forest areas and adjoining lands through systematic planning and implementation, in a cost effective manner;
  5. Restore through natural regeneration or appropriate intervention the forest cover in the country for ecological security and to meet the fuel wood, fodder and other needs of the rural
  6. Restore fuel wood, fodder, timber and other forest produce on the degraded forest and adjoining lands in order to meet the demands for these items.

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