VI SEMESTER
ENVIRONMENTAL SCIENCE AND ENGINEERING (2010-2011)
UNIT-I (Question & Answers)
PART-A (2 Marks)
1. Define the term environment.
Environment can be defined in a number of ways. Some of the definitions are:
1. The sum of all social, biological and physical or chemical factors which compose the surrounding of man.
2. Environment is the representative of physical and chemical components of the earth wherein man is the important factor influencing the surroundings.
3. The sum of all living and non-living factors makes the environment of an organism.
2. Define ecosystem.
Definition
According to Odum Ecosystem is the basic fundamental unit in ecology which includes both the organisms and the non-living environment, each influencing the properties of other and interact necessary for the maintenance of life.
3. Name the two broad classifications of the environment?
4. What do you mean by ecological pyramid?
Ecological Pyramid
In ecosystem food chain process starting from the producer the consumers a regular decrease in the properties or character (such as number, energy and biomass) of the organisms. Since energy is lost as heat in each steps becomes progressively sma1ler the top. This relationship is some times called ecological pyramid.
5. Define sustainable development.
Sustainable Development is defined as ‘the development to meet the needs of the present without compromising the ability of future generations to meet their own needs’. Sustainable Development must balance the needs of society, the economy and the environment.
6. Enumerate the structural and functional elements of ecosystem.
An ecosystem has two major components.
I. Abiotic components,
2. Biotic components.
7. Illustrate the interrelationship among the water, air and land
There exists an intimate relationship between the various components of environment such as air, land or soil and water. There is a constant and continuous exchange of essential elements between the living organisms and environment. The essential chemical elements such as Nitrogen, Oxygen, Carbon, Phosphorus and Sulphur
Example: biogeochemical cycles and photosynthetic mechanism.
8. Write the components of environment?
COMPONENTS OF ENVIRONMENT:
The life supporting environment of planet Earth (which is called as biosphere) is composed of the following three media.
1. Air (Atmosphere).
2. Water (Hydrosphere).
3. Land (Lithosphere).
9. Give one example for producers, consumers and decomposers in an ecosystem?
They are living organisms.
(a) Autotrophs Producers Mainly Green Plants
(b) Heterotrophs: Consumers Mainly animals
(c) Decomposer: Mainly bacteria and fungi
10. What are the four segments of earth’s environment?
The life supporting environment of planet Earth (which is called as biosphere) is composed of the following three media.
Air (Atmosphere).
Water (Hydrosphere).
Land (Lithosphere).
Biosphere
11. What are the major constituents of earth’s atmosphere?
The vertical structure of the atmosphere consists of the following layers.
1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere
5. Exosphere
12. Name the four important biogeochemical cycles in the ecosystem.
Ø Carbon cycle
Ø Nitrogencycle
Ø Sulphur
Ø Phosphorus cycle
13. What is food web and food chain?
FOOD CHAIN
The sequence of the eaters being eaten is called food chain
Food Web
Interlinking pattern of food chain is called “Food Web’
14. What is food chain? Give example.
FOOD CHAIN
In food chain, plants are the only link between the biotic and abiotic components of ecosystem. In any ecosystem a food chain usually starts with green plants. This sequence is called ‘Food chain’.
14. What is known as tropic level?
It is the lowermost layer of atmosphere. This portion extends about 8 km over the earth at poles and 16 km over the earth at the equator.
16. Define biogeochemical cycle.
The characteristic pathway of macro and micronutrients circulation between the organisms and its environment in the biosphere is called as biogeochemical cycles.
17. What are the functions of a hydrological cycle?
Hydrologic cycle is defined as the interchange of water between the atmosphere and the Earth’s surface.
Ø Photosynthesis
Ø Maintaining water level
Ø Flow of energy
18. Mention few natural calamities that affect the ecosystem.
a) Green house effect
b) Tsunami
c) Flood
d) Forest fire
19. What are consumers?
Heterotrophs are the organisms which depend directly or indirectly upon the autotrophs for their food and they are called Consumers.
20. Whether the energy flow is a reversible reaction?
Yes, the energy flow is a reversible reaction.
21. Define sustainable development.
The development to meet the needs of the present without compromising the ability of future generations to meet their own needs.
22. Give a few words about hydrological cycle.
Hydrologic cycle is defined as the interchange of water between the atmosphere and the Earth’s surface.
It’s mainly having three steps
· Evaporation
· Transpiration
· Precipitation
·
23. What is sedimentary cycle?
In these cycles the main reservoir is the soil and the sedimentary and other rocks of the earths crust. Eg: S and P cycle.
24. Draw the nitrogen cycle.
NITROGEN CYCLE: Nitrogen (N constitutes 78% volume of air.)
25. Write the components of hydrosphere.
Components of hydrosphere:
Hydrogen and oxygen.
PART-B (12 Marks)
1. Discuss in detail about (a) Lithosphere (b) Hydrosphere (c) Atmosphere (d) Biosphere
COMPONENTS OF ENVIRONMENT:
The life supporting environment of planet Earth (which is called as biosphere) is composed of the following three media.
Air (Atmosphere).
Water (Hydrosphere).
Land (Lithosphere).
Atmosphere:
Ø Atmosphere is a thin layer of mixed gases covered over the earth. It is composed of mixed gases which make up the air we breathe.
Ø The main function of the atmosphere is to filter the sunlight reaching the earth. The atmosphere screens the dangerous UV radiations from the sun and allows radiations only in the range of 300nm to 2500nm (near UV to near IR) and radio waves.
Ø The atmosphere plays a major role in maintaining the heat balance of the Earth by absorbing the reemitted radiation from the earth.
Ø Atmosphere protects the earth from cosmic radiations and provides life sustaining Oxygen, the macronutrient N2 and CO2 needed for photosynthesis.
Ø The mass of the atmosphere amounts to about 5.7 x 1015 tonnes of air.
Ø Most of the biogeochemical cycles operate between the organisms and the atmosphere.
Ø The processes of evaporation, transpiration and precipitation of water occur between the atmosphere and Earth’s surface.
Composition of air:
COMPONENT % BY VOLUME
Nitrogen 78.08
Oxygen 20.93
Argon 0.93
Carbon dioxide 0.03
Miscellaneous 0.03
Small amounts of H2, He, O3, Ra, Ne, Xe, Kr, SO2, NH3, CH4, H2S etc are part of the miscellaneous components of the air.
Structure of atmosphere:
The vertical structure of the atmosphere consists of the following layers.
1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere
5. Exosphere
1. Troposphere:
Ø It is the lower most layer of the atmosphere.
Ø This portion extends about 8km over the Earth at the poles and 16km over the Earth at the Equator.
Ø Living organisms exists in this region and has strong air movement and cloud formation.
Ø The temperature in this region drops rapidly from -50 to -60oC.
Ø The variation of temperature in this region is inversely proportional to the altitude.
Ø Nitrogen (78.08%), Oxygen (20.93%) are the major composition of troposphere air.
Ø The pollutants in this region are easily diluted or removed by means of rainfall and settling.
Ø The narrow boundary of the troposphere is called as troposphere. The troposphere has constant temperature.
Ø
2. Stratosphere:
Ø The word stratosphere is related to ‘Stratification’ or ‘layering’.
Ø It has a fairly constant temperature of about 0oC.
Ø This region has sufficient amount of ozone. Hence it is also called as ozonosphere. The amount of ozone varies from time to time.
Ø The ozone layer absorbs short wavelength ultra violet solar radiation from the sun. That increases the temperature of the stratosphere with altitude.
Ø This region is free from clouds and airplanes usually fly in the lower zone.
Ø Unlike the troposphere, which cools with altitude, the stratosphere warms with altitude.
3. Mesosphere:
Ø It is the portion above the stratosphere.
Ø It extends about 90 to 100km above the Earth’s surface.
Ø In this portion the temperature decreases with altitude.
Ø This region has cold temperature and low atmospheric pressure.
Ø The temperature drops about -75oC.
Ø The outer portion is called as Mesopause.
4. Thermosphere:
Ø It extends about 500km above the Earth’s surface.
Ø This region has more temperature than the mesopause.
Ø In this portion the temperature increases with altitude.
Ø It contains mixture of N2 and O2 in the ratio of 1:1.
Ø The outer portion of the thermosphere is called as ionosphere.
Ø In the ionosphere, the temperature is about 2000oC and it is characterized by ionization of O2 molecules.
5. Exosphere:
Ø It is the upper most layer of the Earth’s atmosphere.
Ø It extends about 32000km from the surface of the Earth.
Ø In this region, the atoms and particles are away from each other and the collision of particles occurs vary rarely.
Ø The density of air is very low in this region.
Ø In this region of atmosphere, H2, He is the dominant element.
Lithosphere:
The Earth is a cooled, spherical, solid planet of solar system, which rotates on its own axis as well as revolves around the sun at a certain constant distance.
The solid component of the Earth is called Lithosphere. Land is major portion of the lithosphere.
STRUCTURE OF EARTH:
The Earth consists of different layers. The main layers are
1) Crust
2) Mantle
3) Core
1. Core:
Ø It is the central fluid or vaporized sphere of lithosphere.
Ø Radius of the core is about 3440km from the centre of the Earth.
Ø Inner core and outer core are the two subdivisions of the core.
Ø The outer core is in liquid state and inner core is in solid state.
Ø The major components existing in this layer are Nickel and Iron.
Ø The inner core contains nearly pure iron, where as the outer core contains predominantly iron.
Ø The thickness of the outer core is about 2140km and the inner core is about 1300km.
2. Mantle:
Ø It extends about 2900km above the core.
Ø This is in molten state.
Ø It consists of three portions such as upper mantle (400km), transition zone (300km) and lower mantle (2200km).
Ø The density of the lower mantle is more or less equal to that of the upper mantle.
Ø The components of upper mantle are Olivine, Pyroxene and garnet, all are silicate materials.
Ø The transition zone consists of chemically modified forms of Olivine, Pyroxene and garnet.
Ø Oxygen is the most predominant element and silicon is the second most abundant element in the mantle.
Ø In the lower mantle, oxygen is available in oxides.
Ø The components of the lower mantle are silica (SiO2), Magnesium oxide (MgO) and iron oxide (FeO).
3. Crust:
Ø It is the outer most solid layer of the Earth. Its surface is covered with soil.
Ø It is the only part that is supporting rich and varied biotic communities.
Ø The crust and the upper mantle together constitute the lithosphere.
Ø It is about 30km above the mantle.
Ø Oxygen is the most predominant element and silicon is the second most abundant element.
Ø Silicates of Al, Ca, Fe, Mg, K and Na are abundantly available in the crust.
Hydrosphere:
Leonardo da Vinci said, “Water is the driver of life on the Earth”. The human body consists about 65% of water. Among many essential elements for the existence of living beings water is rated as the most important. cannot Being a universal solvent, it is the important factor in determining the structure, function and distribution of ecosystems.
The process of growth, respiratory mechanism and reproduction are the vital processes that are affected by water availability.
The original source of water is precipitation from the atmosphere. About 75% of the Earth’s surface is covered by hydrosphere.
Hydrologic cycle:
Hydrologic cycle is defined as the interchange of water between the atmosphere and the Earth’s surface.
Evaporation of water from water bodies (like oceans and lakes) and transpiration of water from green plants form clouds in the atmosphere. By cooling of the clouds, precipitation of the water is produced. It makes runoff over the Earth’s surface. The runoff is taken by the soil ands the plants for photosynthesis and the excess water flows in to the streams, rivers, lakes and oceans. Approximately about 2/3 of the precipitation evaporates quickly or transpired by vegetations. Flood and drought are caused by natural variations in precipitation.
Fresh water Environment:
Fresh water is the home for numerous organisms and it can be divided into two groups.
1. Standing water (or) Lentic water. Eg: Lake , pond, swamp etc.
2. Running water (or) Lotic water. Eg: Spring, stream, river etc.
Zones of Aquatic environment:
The aquatic environment can be divided into three zones.
1. Littoral zone.
2. Limnetic zone.
3. Profundal zone.
1. Littoral zone:
It is the top layer of the lake. Light can reach up to the bottom of this layer. Rooted plants occupy this portion and they have projected leaves above the water surface for photosynthesis. Mesophytic plants and phytoplanktons are usually found in this zone. In this region frog, turtles and water snakes are also found.
2. Limnetic zone:
This is the intermediate zone of a lake. The depth of this zone is up to the depth of effective light penetration. Plankton, nektons and neustons are the biotic community in this zone. This zone includes floating hydrophytes and submerged hydrophytes. The primary produces of this zone are hydrophytes and phytoplanktons. The consumers of this zone are zooplankton, fish and others.
3. Profundal zone: it is the bottom and deep most portion of the lake. The sunlight does not penetrate in this zone. Hence producer organisms are present in this zone. The organisms living in the bottom sediments are called as benthos.
Fresh water organisms:
Benthos → organisms living in bottom sediments.
Periphyton → organisms living on stems and leaves.
Plankton → organisms flying with the water current.
Nekton → organisms swimming and navigating in water.
Neuston → organisms resting or swimming on the water surface.
2. With typical examples explain the interrelationship between the components and subcomponents of the environment.
There exists an intimate relationship between the various components of environment such as air, land or soil and water. There is a constant and continuous exchange of essential elements between the living organisms and environment. The essential chemical elements such as Nitrogen, Oxygen, Carbon, Phosphorus and Sulphur
Example: biogeochemical cycles and photosynthetic mechanism.
BIOGEOCHEMICAL CYCLES
The characteristic pathway of macro and micronutrients circulation between the organisms and its environment in the biosphere is called as biogeochemical cycles.
Examples:
CARBON CYCLE
In all the organic compounds, carbon is the basic component. It is consent in the food components as carbohydrates, proteins, fats and amino acids.
Carbon cycle is an example of gaseous cycle.
The main steps of carbon cycle are,
1. During photosynthesis process plants utilize carbon dioxide to prepare carbohydrates and liberate oxygen in the presence of sun light. This oxygen is utilized by animals.
2.The green plants are eaten by animal as food. So carbon in the form of plant carbohydrates passes as food to animals.
3. When plant and animals respiration process liberates CO in the atmosphere
4. Combustion of coal and weathering of rocks also release CO to the reservoir pool.
5. Some of the dead plants and animals when this fuel CO is added to the atmosphere.
6. Volcanic eruptions also release CO in atmosphere.
7. The carbon of CO is used again and again by living goes on continuously.
NITROGEN CYCLE: Nitrogen (N constitutes 78% volume of air.
1. Natural Fixation
(a) Gaseous nitrogen which is converted into nitrates by fixing bacteria and certain blue green algae.
(b) Lightning also converts gaseous nitrogen and convert the same into nitrates.
2. The nitrogen containing proteins foods are passed to animals.
3. The decomposition of dead plants and animals releases ammonia by the
process called ammonification.
4. Ammonia becomes converted into nitrates or free nitrogen.
These processes are done by bacterial activities.
Photosynthesis:
The biochemical mechanism involving the formation of starch in green plants in the presence of chlorophyll pigments and sunlight is called photosynthesis.
CO2 + H2O Sunlight Starch + O2 ↑Chlorophyll
The repeated sequences of both light and dark reactions result in the subsequent generation of starch as final source of energy for the green plants.
3. Describe the various components of ecosystem structure.
ECOSYSTEM
The term eco means ‘environment’ and system means ‘coordinated complex’. The ecosystem is the basic functional unit in ecology.
It consists of living organisms (biotic) and non-living substances (Abiotic) and their interactions.
Definition
According to Odum Ecosystem is the basic fundamental unit in ecology which includes both the organisms and the non-living environment, each influencing the properties of other and interact necessary for the maintenance of life.
Ecosystem is broadly classified into 2 major types Natural and artificial. Natural ecosystem is the one which is formed by the nature without the dependence of man. It is further divided in to two categories: Terrestrial Ecosystem and Aquatic system. Artificial ecosystem is the one which is formed by the activity of man based on their needs.
Eg: Crop fields and Gardens.
Ecosystem |
Natural Artificial
E.g. cropping of lands
Terrestrial Aquatic E.g. Forest ,
Grassland,
Desert
Fresh water Marine water |
Lentic Lotic
(Stagnant) (Free flowing)
Terrestrial Ecosystem
It is the study of the ecosystem on the land area. Eg: Grassland ecosystem, Desert ecosystem, forest ecosystem.
Aquatic Ecosystem
It is the study of the ecosystem on water. It is further classified into the following two types on the basis salt contents in water.
1. Fresh water ecosystem, e.g., Pond, Lake , River.
2. Marine or Oceanic ecosystem e.g., Ocean ecosystem
STRUCTURE OF AN ECOSYSTEM
An ecosystem has two major components.
I. Abiotic components,
2. Biotic components.
1. ABIOTIC COMPONENTS
They are non-living components composed of inorganic substances such as water, oxygen, carbon dioxide, hydrogen, nitrogen, phosphorus, calcium, etc. and the organic substances like proteins, carbohydrates, fats, amino acids, and the physical factors like light, temperature, wind and humidity.
2. BIOTIC COMPONENTS
They are living organisms.
(a) Autotrophs Producers Mainly Green Plants
(b) Heterotrophs: Consumers Mainly animals
(c) Decomposer: Mainly bacteria and fungi
a) AUTOTROPHS (or) PRODUCERS:
Producers are autotrophic organisms like chemosynthetic and Photosynthetic bacteria, blue green algae, and other green plants. These organisms capture solar energy from sunlight and with the help of the abiotic factors they will prepare the food materials in the form of carbohydrate, proteins, lipids and fats by the process of photosynthesis.
b) HETEROTROPHS (or) CONSUMERS
Heterotrophs are the organisms which depend directly or indirectly upon the autotrophs for their food and they are called Consumers. They are again further subdivided in to three types. They are
(a) Primary Consumers
They are Herbivorous animals that depend directly on green plants for their food. e.g., rabbit, goat, deer, cow, horse.
(b) Secondary Consumers
They are Carnivores which feed on the primary consumers. They are chiefly insects, beetles, mites, termites and fish.
(c) Tertiary Consumers
These are the top carnivores which feed upon the secondary consumer for their food. e.g., lion, tiger.
c) DECOMPOSERS
Bacteria and fungi are the prime factors of this decomposition process. Enzymes are secreted from plant and animal debris. The enzymes convert the complex form of the dead organism into small molecules which can be absorbed by the fungi. Finally organic and inorganic salts are the final end product of this decomposition process and it is again taken up by the plants for photosynthesis.
4. Write a detailed note on development and evolution of ecosystem.
DEVELOPMENT AND EVOLUTION OF ECOSYSTEM
Ecosystem development refers to the gradual changes in structure of species and community processes within an environment. It is also termed as ecological succession. An unstable community with in a specific environment changes into other forms of communities from time to time. Conversion of pond community into marshy – land community is an example for ecological succession.
Basically there are two types of ecological succession:
1) When the changes are caused and induced by the internal factors, the process is called autogenic succession.
2) When eternal factors outside environment such as storms and fires, force the changes, the process is called allogenic succession.
In terms of communities, succession is grouped in to two categories.
1) Primary Succession: when a new community develops on a sterile area that has not been previously occupied, it is called primary succession.
2) Secondary succession: When a community starts developing on areas which are already inhabited by well known communities, it is called secondary succession.
Various developmental stages involved in the development and succession of a community are called sere. Each of these developmental stages is called serial stage. The stable community that is finally formed is called climax community. The first groups of organisms that initiate the sequences of changes of ecosystem development or succession are known as pioneer species.
Internal and external influences:
Inflow of materials and energy, geological forces and human disturbances are found to cause serious alterations on the development of an ecosystem. When nutrients and soil materials enter the lake from outside such as watershed, the process of eutrophication of Lake Ecosystem
Periodical disturbances would definitely affect successional process when the ecosystem development occurs for a long duration of time as in the case of forest development from a bare ground. Abundant storage of nutrient materials and an enhanced nutrient cycling are very important for the development of an ecosystem.
Evolution of biosphere:
The long termed evolution of ecosystem as biosphere is mostly determined by external forces called allogenic forces such as geological and climatic changes and internal processes called autogenic processes that are formed by the activities of the organisms of the ecosystem. The primitive ecosystems that originated 3 billion years ago contained mostly anaerobic heterotrophs which depend on the organic matter synthesized from abiotic processes. This was followed by the massive evolution of algal autotrophs which converted a reduced atmosphere in to an oxygenic one. From that time onwards, there has been a steady evolution of organisms with complex and diverse systems comprising highly organized multicellular bodies.
When life first originated on earth before 3 billion years ago, nitrogen, ammonia, hydrogen, carbon monoxide, methane and water vapour were the important atmospheric constituents and there was no availability of any free oxygen resulted in the lacking of ozone layer and the UV radiation directly diffused into the terrestrial and aquatic surfaces. Surprisingly, the dissociation of water vapour formed from small amount of non-biological oxygen molecules, formed the ozone shield to absorb UV radiation from reaching Earth surface. This chemical evolution resulted in the generation of amino acids and other basic organic molecules for the origin of primitive life.
The aquatic yeast anaerobic organisms were the first living organisms to have evolved and derived their energy source from the anaerobic respiration. Because of non availability of an effective oxidative respiratory mechanism, primitive life could evolve into only non nucleated prokaryotes. This could further reveal the existence of life in a precarious condition for several millions of years. In 1966, Marshall
Various evolutionary data appears to confirm the fact that first multicellular organisms called metazoans originated about 700 million ago, when the atmospheric oxygen content reached about 8%. Subsequent evolution and development of green plants tremendously increased the sources of oxygen supply that increased the population of living organisms over the Earth and also favored the evolution of giant sized dinosaurs, mammals and humans.
5. Explain with a neat diagram of different zones of the earth’s atmosphere and
their characteristics.
Structure of atmosphere:
The vertical structure of the atmosphere consists of the following layers.
1. Troposphere
2. Stratosphere
3. Mesosphere
4. Thermosphere
5. Exosphere
1.Troposphere:
Ø It is the lower most layer of the atmosphere.
Ø This portion extends about 8km over the Earth at the poles and 16km over the Earth at the Equator.
Ø Living organisms exists in this region and has strong air movement and cloud formation.
Ø The temperature in this region drops rapidly from -50 to -60oC.
Ø The variation of temperature in this region is inversely proportional to the altitude.
Ø Nitrogen (78.08%), Oxygen (20.93%) are the major composition of troposphere air.
Ø The pollutants in this region are easily diluted or removed by means of rainfall and settling.
Ø The narrow boundary of the troposphere is called as troposphere. The troposphere has constant temperature.
2.Stratosphere:
Ø The word stratosphere is related to ‘Stratification’ or ‘layering’.
Ø It has a fairly constant temperature of about 0oC.
Ø This region has sufficient amount of ozone. Hence it is also called as ozonosphere. The amount of ozone varies from time to time.
Ø The ozone layer absorbs short wavelength ultra violet solar radiation from the sun. That increases the temperature of the stratosphere with altitude.
Ø This region is free from clouds and airplanes usually fly in the lower zone.
Ø Unlike the troposphere, which cools with altitude, the stratosphere warms with altitude.
3.Mesosphere:
Ø It is the portion above the stratosphere.
Ø It extends about 90 to 100km above the Earth’s surface.
Ø In this portion the temperature decreases with altitude.
Ø This region has cold temperature and low atmospheric pressure.
Ø The temperature drops about -75oC.
Ø The outer portion is called as Mesopause.
4.Thermosphere:
Ø It extends about 500km above the Earth’s surface.
Ø This region has more temperature than the mesopause.
Ø In this portion the temperature increases with altitude.
Ø It contains mixture of N2 and O2 in the ratio of 1:1.
Ø The outer portion of the thermosphere is called as ionosphere.
Ø In the ionosphere, the temperature is about 2000oC and it is characterized by ionization of O2 molecules.
5.Exosphere:
Ø It is the upper most layer of the Earth’s atmosphere.
Ø It extends about 32000km from the surface of the Earth.
Ø In this region, the atoms and particles are away from each other and the collision of particles occurs vary rarely.
Ø The density of air is very low in this region.
Ø In this region of atmosphere, H2, He is the dominant element.
6. Explain carbon and nitrogen cycles as applicable to ecosystem.
CARBON CYCLE
In all the organic compounds, carbon is the basic component. It is consent in the food components as carbohydrates, proteins, fats and amino acids.
Carbon cycle is an example of gaseous cycle.
The main steps of carbon cycle are,
1. During photosynthesis process plants utilize carbon dioxide to prepare carbohydrates and liberate oxygen in the presence of sun light. This oxygen is utilized by animals.
2.The green plants are eaten by animal as food. So carbon in the form of plant carbohydrates passes as food to animals.
3. When plant and animals respiration process liberates CO in the atmosphere
4. Combustion of coal and weathering of rocks also release CO to the reservoir pool.
5. Some of the dead plants and animals when this fuel CO is added to the atmosphere.
6. Volcanic eruptions also release CO in atmosphere.
7. The carbon of CO is used again and again by living goes on continuously.
NITROGEN CYCLE: Nitrogen (N constitutes 78% volume of air.
1. Natural Fixation
(a) Gaseous nitrogen which is converted into nitrates by fixing bacteria and certain blue green algae.
(b) Lightning also converts gaseous nitrogen and convert the same into nitrates.
2. The nitrogen containing proteins foods are passed to animals.
3. The decomposition of dead plants and animals releases ammonia by the
process called ammonification.
4. Ammonia becomes converted into nitrates or free nitrogen.
These processes are done by bacterial activities.
7. State and explain in detail about the various human activities and their impact on the environment.
Impacts of Man made sources of pollution:
The pollution of water, air and land are created and developed every day. They are made more complicated due to rapid growth of industries and population. Some of the anthropogenic sources of pollution are
1. Industrial development
2. Rapid growth of Automobiles
3. Uncontrolled population growth
4. Deforestation
5. Over exploitation of natural resources
6. Use of fertilizers, pesticides etc., in agricultural activities
7. Mining activities
8. Nuclear explosions
Impacts on Atmosphere:
Ø The dust and carbon particle make our cities dirty, spoil our material goods.
Ø Coal smog reduces visibility and is a major cause of traffic accidents.
Ø Inhalation of asbestos fibers causes a serious occupational and health problem (asbestosis), which leads to cancer and even death.
Ø The exhaust gas of automobiles contains more amount of unburnt fuel with more carbon monoxide. Inhalation of carbon monoxide in human beings leads to carboxy hemoglobin, which carries the oxygen carrying capacity of blood.
Ø The emissions from various types of industries and automobiles contain Sulphur-dioxide and nitrogen oxides. These gases combine with rain, smog and fog form acid rain.
Ø Release of CFC into the atmosphere causes depletion of ozone layer. That makes more health problems such as skin cancer and eye disorders in human beings.
Ø The release of air pollutants into the atmosphere increase the atmospheric temperature, known as global warming. The major effects are melting of ice caps, rising in sea levels and variation in seasons.
Impacts on Land:
Ø Disposal of industrial effluents and domestic wastes on land causes loss of its fertility.
Ø Removal of the top soil of land causes low fertility for crop production.
Ø Deforestation, the process of changing land use from forestry to a non forest use, is threatening the existence of many species.
Impacts on Water:
Ø Change in colour will affect the usage of water and growth of plants and organism of water.
Ø The dissolved oxygen content of the water body is reduced by organic substances.
Ø The water becomes unfit for drinking and other purposes because of inorganic substances.
Ø Oil and other lubricants will affect the self purification of the water body.
Ø Enrichment of nutrients (Eutrophication) from surrounding watershed affects the penetration of light through the water, causing damage to the characteristics of that water and aquatic life.
Ø Sewage disposed into water bodies’ results in many water borne infectious diseases to the human beings. The different types of organisms and water borne diseases are
Water Borne Diseases | Responsible Organism |
Typhoid, paratyphoid, Diarrhoea, Cholera, Bacillary dysentery | Bacteria |
Amoebiasis, Giardiasis | Protozoa |
ViralHepatitis (Jaundice), Poliomyelitis | Virus |
Round worm, hookworm, threadworm | Helminths |
Ø Disposal of coolant water used in industries increase the temperature of the surface water. This increase in temperature affects the aquatic ecosystem.
Ø More amounts of nitrates in water due to the application of artificial fertilizer in agricultural lands can cause methemoglobinemia known as blue baby disease.
8. Briefly explain how natural calamities disturb the environment.
Natural calamites:
i) Forest fires produce more smoke and trace gases into the atmosphere.
Ø The dust and carbon particle make our cities dirty, spoil our material goods.
Ø Coal smog reduces visibility and is a major cause of traffic accidents
Ø Inhalation of asbestos fibers causes a serious occupational and health problem (asbestosis), which leads to cancer and even death
Ø Inhalation of carbon monoxide in human beings leads to carboxy hemoglobin, which carries the oxygen carrying capacity of blood.
Ø The release of air pollutants into the atmosphere increase the atmospheric temperature, known as global warming. The major effects are melting of ice caps, rising in sea levels and variation in seasons.
ii) Explosive Volcanic eruptions can inject more SO2, smoke, particulate matter and trace gases.
Ø Sulphur-dioxide and nitrogen oxide gases combine with rain, smog and fog form acid rain.
Impacts of acid rain:
· It damages to building and structural materials.
· Acidifies soil leading to reduced productivity of crops.
· Destroys plant tissues.
· Affects aquatic system.
iii) Dust storms are the main cause for wind blow dust in the air.
iv) Natural contaminants present in the air like bacteria, spores, cysts and pollens are more dangerous when inhaled.
v) Carbon monoxide will be produced from the breakdown of methane gas in the marsh lands.
vi) Spraying of salts from oceans.
vii) Electrical storms produce oxides of nitrogen in the atmosphere which leads to ozone depletion.
Effects:
· It damages immune system in human beings and causes.
· It causes skin cancer and sun burns.
· It is now revealed that excessive exposure to UV rays causes leukemia and breast cancer.
· It causes cataract.
· It destroys plant proteins.
viii) Flood - Unusual great quantity of water flowing in an area is called flood.
It causes soil erosion, landslides, overflow of water in their river banks and submerging of surrounding areas.
ix) Earthquakes – is a sudden shaking of the earth.
· tectonic plates of solid rocks moving across their boundaries
· resulting sudden fractures across the boundaries of the plates
· damage the building structures.
9. Explain the structure and functional components of an ecosystem in a brief manner.
STRUCTURE AND FUNCTION OF AN ECOSYSTEM
An ecosystem has two major components.
I. Abiotic components,
2. Biotic components.
1. ABIOTIC COMPONENTS
They are non-living components composed of inorganic substances such as water, oxygen, carbon dioxide, hydrogen, nitrogen, phosphorus, calcium, etc. and the organic substances like proteins, carbohydrates, fats, amino acids, and the physical factors like light, temperature, wind and humidity.
2. BIOTIC COMPONENTS
They are living organisms.
(a) Autotrophs Producers Mainly Green Plants
(b) Heterotrophs: Consumers Mainly animals
(c) Decomposer: Mainly bacteria and fungi
b) AUTOTROPHS (or) PRODUCERS:
Producers are autotrophic organisms like chemosynthetic and Photosynthetic bacteria, blue green algae, and other green plants. These organisms capture solar energy from sunlight and with the help of the abiotic factors they will prepare the food materials in the form of carbohydrate, proteins, lipids and fats by the process of photosynthesis.
b) HETEROTROPHS (or) CONSUMERS
Heterotrophs are the organisms which depend directly or indirectly upon the autotrophs for their food and they are called Consumers. They are again further subdivided in to three types. They are
(a) Primary Consumers
They are Herbivorous animals that depend directly on green plants for their food. e.g., rabbit, goat, deer, cow, horse.
(b) Secondary Consumers
They are Carnivores which feed on the primary consumers. They are chiefly insects, beetles, mites, termites and fish.
(c) Tertiary Consumers
These are the top carnivores which feed upon the secondary consumer for their food. e.g., lion, tiger.
c) DECOMPOSERS
Bacteria and fungi are the prime factors of this decomposition process. Enzymes are secreted from plant and animal debris. The enzymes convert the complex form of the dead organism into small molecules which can be absorbed by the fungi. Finally organic and inorganic salts are the final end product of this decomposition process and it is again taken up by the plants for photosynthesis.
FUNCTIONS OF AN ECOSYSTEM
1. In the ecosystem, biotic components and other materials like N2, C, H2, P and S circulated within and outside of the system.
2. The energy is transferred from one trophic level to the other in the form of a chain called as food chain.
3. The important source of energy is the sun.
4. Some factors which are responsible for high productivity are high temperature, rainfall and decomposition of dead organic matter.
5. Climatic changes on functioning of ecosystems.
6. Production, consumption, and Decomposition are functions of ecosystem.
10. Describe the energy flow in ecosystem and the factors which are controlling it.
ENERGY FLOW
Energy is defined as the capacity to do work. Biological activity requires neutralization of energy which ultimately comes from the sun. a fraction is about 1/50millionth of the total radiation reaches the Earth’s atmosphere. Solar radiation travels through the space in the form of waves, most radiations are lost in space.
In ecological energetics, we study
(i) Quantity of solar energy reaching an ecosystem.
(ii) Quantity of energy used by green pants for photosynthesis.
(iii) Quantity and path of energy flow from producers to consumers.
About 34% of the sunlight reaching the earth’s atmosphere is reflected back into its atmosphere, 10% is held by ozone layer, water vapour and other atmospheric gases. The rest 56% reaches the earth’s surface.
Only a fraction of this energy reaches the earth’s surface is used by green plants for photosynthesis and the rest is absorbed as heat by ground vegetation or water. Infact, only about 0.02% of the sunlight reaching the atmosphere is used in photosynthesis. Nevertheless, it is this small fraction on which all the organisms of the ecosystem depend.
The green plants convert the radiant energy received in the form of electromagnetic waves released from the sun during the transmutation of H2 and He. The light energy is fixed by the green plants through their chlorophyll pigments by the process of photosynthesis.
6CO2 + 12H2O chlorophyll C6H12O6+ 6H2OIn the process of photosynthesis 673k.cal energy is fixed for the synthesis of each molecule of carbohydrate. This is the first step in the production of food and is called as Gross primary productivity or Gross photosynthesis. Out of the total amount of energy fixed by the plants, some is released again in respiration. The remaining energy is used in building up of the tissue and organs. It is called Net primary production or Net photosynthesis. The chemical energy is stored in the plants are then transfers to subsequent consumers through the food chain and food web by ‘eating’ and ‘eaten process’. The behavior of energy in an ecosystem can be termed as energy flow.
The flow of energy is always unidirectional and described by two basic principles of thermodynamics.
1. Energy can neither be created nor be destroyed but can only be transformed from one form to another. This is known as the first law of thermodynamics. The conclusion of this law is energy flow is unidirectional. i.e. the energy captured by autotrophs does not revert to the solar input. Due to the one way flow of energy, the system would collapse if the primary source, the sun were cut off.
2. Energy transfer is always accompanied by dispersion of energy into unavailable heat (i.e. entropy). This law is known as the second law of thermodynamics or the law of entropy. From this law, there is a progressive decrease in energy content at each trophic level. This happens due to dissipation of heat in metabolic activities and is measured as respiration coupled with unutilized energy.
Energy flow diagram for a lake (Fresh water Ecosystem) in gcal/cm2/yr (Odum, 1972)
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Solar radiation 118.872
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