ASSIGNMENT No. 1

1. 1 Define the following terms in your own words.

• Geological Cycle

The geologic cycle is a collective term used to describe the complex interactions between the component sub-cycles of tectonic, hydrologic, rock, and the biological cycling of elements known as the biogeochemical cycle. These various subcycles influence each other and may produce natural hazards and processes important to environmental geology such as landslides, earthquakes, volcanic activity, flooding, groundwater flow, and weather. The rock cycle is influenced by all the other geologic subcycles. For example, tectonic processes provide the pressure and heat necessary to recrystalize some or all of the minerals in a rock and transform it from one rock type to another.

• Detritus

Detritus is dead particulate organic material, as distinguished from dissolved organic material. Detritus typically includes the bodies or fragments of bodies of dead organisms, and fecal material. Detritus typically hosts communities of microorganisms that colonize and decompose (i.e. remineralize) it. In terrestrial ecosystems it is present as leaf litter and other organic matter that is intermixed with soil, which is denominated “soil organic matter“. The detritus of aquatic ecosystems is organic material that is suspended in the water and accumulates in depositions on the floor of the body of water; when this floor is a seabed, such a deposition is denominated “marine snow“.

• Tectonic Cycle

A period of geologic history that is characterized by a certain sequence of tectonic and other geologic events. Such periods last for more than 100 million years. Tectonic cycles are evidenced most clearly in geosynclinal regions, where the cycle begins with the subsidence of the crust and the formation of deep marine basins. The first phase is characterized by the accumulation of thick layers of sediments, by submarine volcanism, and by the formation of basic and ultrabasic intrusive magmatic rocks

• Mountain range

A mountain range or hill range is a series of mountains or hills ranged in a line and connected by high ground. A mountain system or mountain belt is a group of mountain ranges with similarity in form, structure, and alignment that have arisen from the same cause, usually an orogeny.^[1] Mountain ranges are formed by a variety of geological processes, but most of the significant ones on Earth are the result of plate tectonics. Mountain ranges are also found on many planetary mass objects in the Solar System and are likely a feature of most terrestrial planets.

Mountain ranges are usually segmented by highlands or mountain passes and valleys. Individual mountains within the same mountain range do not necessarily have the same geologic structure or petrology. They may be a mix of different orogenic expressions and terranes, for example thrust sheets, uplifted blocks, fold mountains, and volcanic landforms resulting in a variety of rock types.

• Soil Erosion

Soil erosion is a gradual process that occurs when the impact of water or wind detaches and removes soil particles, causing the soil to deteriorate. Soil deterioration and low water quality due to erosion and surface runoff have become severe problems worldwide. The problem may become so severe that the land can no longer be cultivated and must be abandoned. Many agricultural civilizations have declined due to land and natural resource mismanagement, and the history of such civilizations is a good reminder to protect our natural resources.

Erosion is a serious problem for productive agricultural land and for water quality concerns. Controlling the sediment must be an integral part of any soil management system to improve water and soil quality.

• Environmental Science

Environmental science is an interdisciplinary academic field that integrates physics, biology, and geography (including ecology, chemistry, plant science, zoology, mineralogy, oceanography, limnology, soil science, geology and physical geography, and atmospheric science) to the study of the environment, and the solution of environmental problems. Environmental science emerged from the fields of natural history and medicine during the Enlightenment. oday it provides an integrated, quantitative, and interdisciplinary approach to the study of environmental systems. Environmental studies incorporates more of the social sciences for understanding human relationships, perceptions and policies towards the environment. Environmental engineering focuses on design and technology for improving environmental quality in every aspect.

• Air Pollution

Air pollution is contamination of the indoor or outdoor environment by any chemical, physical or biological agent that modifies the natural characteristics of the atmosphere. Household combustion devices, motor vehicles, industrial facilities and forest fires are common sources of air pollution. Pollutants of major public health concern include particulate matter, carbon monoxide, ozone, nitrogen dioxide and sulfur dioxide. Outdoor and indoor air pollution cause respiratory and other diseases and are important sources of morbidity and mortality.

• Infiltration

Infiltration is defined as the flow of water from aboveground into the subsurface. The topic of infiltration has received a great deal of attention because of its importance to topics as widely ranging as irrigation, contaminant transport, groundwater recharge, and ecosystem viability. More generally, a quantitative understanding of this process is vital to our ability to relate surface and subsurface processes in describing the hydrologic cycle.

 

• Genetic diversity

Genetic Diversity refers to the range of different inherited traits within a species. In a species with high genetic diversity, there would be many individuals with a wide variety of different traits. Genetic diversity is critical for a population to adapt to changing environments. If a highly selected and low diversity strain, like fish populations grown for aquaculture, is introduced into the wild population, it will reduce the population’s ability to adapt to changes.

• Reservoirs

A reservoir is most commonly an enlarged natural or artificial lake created using a dam to store fresh water. Reservoirs can be created in a number of ways, including controlling a watercourse that drains an existing body of water, interrupting a watercourse to form an embayment within it, through excavation, or building any number of retaining walls or levees.Defined as a storage space for fluids, reservoirs may hold water or gasses, including hydrocarbons. Tank reservoirs store these in ground-level, elevated, or buried tanks.

1. 2 Differentiate between the following with examples
2. i) Lichens and Mycorrhiza

Lichen is a mutualistic relationship that exists between an algae/cyanobacterium and a fungus. In this association, one party is responsible for the production of food by photosynthesis while the other party is responsible for the absorption of water and providing shelter. Mycorrhiza is another example of a mutualistic relationship. It occurs between roots of a higher plant and a fungus. Fungus inhabits the roots of higher plant without harming the roots. The key difference between lichen and mycorrhizae is that lichen is a mutualistic association that exists between an algae/cyanobacterium and a fungus, while mycorrhiza is a type of mutualistic association occurring between roots of a higher plant and a fungus.

1. ii) Intrusive and Extrusive rocks

Igneous rocks are one of three main types of rocks (along with sedimentary and metamorphic), and they include both intrusive and extrusive rocks. The two main categories of igneous rocks are extrusive and intrusive. Extrusive rocks are formed on the surface of the Earth from lava, which is magma that has emerged from underground. Intrusive rocks are formed from magma that cools and solidifies within the crust of the planet.

         iii) Velamen and Host

Epiphytic plants are those small plants that grow on the stem or branches of large trees. They depend on the large plants just as a holding surface. Epiphytic plants have two types of roots;

·           The clinging roots; that helps the epiphytic plant to get fixed on the barks of the tree.

·           The epiphytic roots; that hangs freely in the air and absorbs moisture and stores it with the help of specialized tissue called velamen.

Whereas, Parasitic plants are those that solely depends on a host plant for the nutrition. Roots of the parasitic plants, called as Haustoria or sucking roots, are small and specialized so that to penetrate into and absorb water and nutrients from the host tissue.

1. iv) Grazing and Predation

A food chain where the energy is gained by the organisms is from photosynthesis; it is termed as the grazing food chain. n a detritus food chain, the main source of nutrition is dead plants or animals. The detritus food chain does not depend on solar energy. The organisms that gain their energy from the dead remains of the plants or animals are known as detrivores or decomposers. Grazing food chain is directly dependent on the flow of solar energy and thus, the gross production of plants might be oxidized during respiration or can be eaten by herbivores or they may die and decay. In the grazing food chain, sunlight energy serves as the primary source of energy. Energy for the detritus food chain is from the dead and decomposed matter known as detritus. Detritus food chain acquires energy from detritus, utilizing the detritus to its fullest, with minimum wastage. The grazing Food Chain helps in the fixation of inorganic nutrients.

1. v) Social and Economic man

Economic Man tends to be concerned primarily with producing goods and services, with quantitative problems. Social Man is more concerned with how goods and services are distributed among people, and with qualitative problems. Economic Man ex-presses values in money terms. Social Man ten’ ds to measure more readily in human terms. The driving force behind Economic Man is work and discipline in the tradition of the Puritan Ethic and in the environment of competition. The driving force behind Social Man is self-realization in an environment of cooperation.

1. 3
2. Define types and importance of Environmental Science.

Environmental science is an interdisciplinary academic field that integrates physical, biological and information sciences (including ecology, biology, physics, chemistry, plant science, zoology, mineralogy, oceanography, limnology, soil science, geology and physical geography, and atmospheric science) to the study of the environment, and the solution of environmental problems.

The environment is an evergreen subject because it matters a lot to our daily lives. It’s where we live, eat, breathe, and bring up our children. Our life support systems entirely rely on the well-being of every organism living on planet earth. This is why a lot has been written and spoken about the protection and conservation of the environment. There are even high-value courses dedicated to the study of the environment. A typical example is an environmental science.

Environmental science is a field that deals with the study of the interaction between human systems and natural systems. Natural systems involve the earth itself and life. Human systems are primarily the populations of the earth.

Components of Environmental Science

1. Ecology

Ecology is the study of organisms and the environment interacting with one another. Ecologists, who make up a part of environmental scientists, try to find relations between the status of the environment and the population of a particular species within that environment, and if there are any correlations to be drawn between the two.

Geoscience

Geoscience concerns the study of geology, soil science, volcanoes, and the Earth’s crust as they relate to the environment. As an example, scientists may study the erosion of the Earth’s surface in a particular area. Soil scientists, physicists, biologists, and geomorphologists would all take part in the study.

Geomorphologists would study the movement of solid particles (sediments), biologists would study the impacts of the study to the plants and animals of the immediate environment, physicists would study the light transmission changes in the water causing the erosion, and the soil scientists would make the final calculations on the flow of the water when it infiltrates the soil to full capacity causing the erosion in the first place.

Atmospheric Science

Atmospheric science is the study of the Earth’s atmosphere. It analyzes the relation of the Earth’s atmosphere to the atmospheres of other systems. This encompasses a wide variety of scientific studies relating to space, astrology, and the Earth’s atmosphere: meteorology, pollution, gas emissions, and airborne contaminants.

An example of atmospheric science is where physicists study the atmospheric circulation of a part of the atmosphere, chemists would study the chemicals existent in this part and their relationships with the environment, meteorologists study the dynamics of the atmosphere, and biologists study how the plants and animals have affected and their relationship with the environment.

 Environmental Chemistry

Environmental Chemistry is the study of the changes chemicals make in the environment, such as contamination of the soil, pollution of the water, degradation of chemicals, and the transport of chemicals upon the plants and animals of the immediate environment.

Importance of Environmental Science

To Realize That Environmental Problems are Global

Environmental science lets you recognize that environmental problems such as climate change, global warming, ozone layer depletion, acid rains, and impacts on biodiversity and marine life are not just national problems, but global problems as well. So, concerted effort from across the world is needed to tackle these problems.

To Understand the Impacts of Development on the Environment

It’s well documented and quantified that development results in Industrial growth, urbanization, expansion of telecommunication and transport systems, hi-tech agriculture, and expansion of housing. Environmental science seeks to teach the general population about the need for decentralization of industries to reduce congestion in urban areas. Decentralization means many people will move out of urban centers to reduce pollution resulting from overpopulation.

The goal is to achieve all this sustainably without compromising the future generation’s ability to satisfy their own needs.

To Discover Sustainable Ways of Living

Environmental science is more concerned with discovering ways to live more sustainably. This means utilizing present resources in a manner that conserves their supplies for the future.

Environmental sustainability doesn’t have to outlaw living luxuriously, but it advocates for creating awareness about the consumption of resources and minimizing unnecessary waste.

This includes minimizing household energy consumption, using disposals to dispose of waste, eating locally, recycling more, growing your own food, drinking from the tap, conserving household water, and driving your car less.

To Utilize Natural Resources Efficiently

Natural resources bring a whole lot of benefits to a country. A country’s natural resources may not be utilized efficiently because of low-level training and a lack of management skills.

To Learn and Create Awareness about Environmental Problems at Local, National and International Levels

Environmental problems at local, national, and international levels mostly occur due to lack of awareness. Environmental science aims to educate and equip learners with the necessary environmental skills to pass to the community in order to create awareness.

Environmental awareness can be created through social media, creating a blog dedicated to creating awareness, community-centered green clubs, women forums, and religious podiums.

b       Write down note on the following:

                  i        Elements of Environment

The three main components of the environment are the lithosphere, the atmosphere and the hydrosphere. The lithosphere is the solid portion of the earth. The gaseous layers that surround the earth is the atmosphere. The atmosphere is made up of oxygen, nitrogen, carbon dioxide and other gases. The hydrosphere refers to the big area of water that covers the earth’s surface. This water is in the forms of ice, water and water vapour.

                  ii       Ecological Pyramid

An ecological pyramid (also trophic pyramid, Eltonian pyramid, energy pyramid, or sometimes food pyramid) is a graphical representation designed to show the biomass or bioproductivity at each trophic level in a given ecosystem. A pyramid of energy shows how much energy is retained in the form of new biomass at each trophic level, while a pyramid of biomass shows how much biomass (the amount of living or organic matter present in an organism) is present in the organisms. There is also a pyramid of numbers representing the number of individual organisms at each trophic level. Pyramids of energy are normally upright, but other pyramids can be inverted or take other shapes. Ecological pyramids begin with producers on the bottom (such as plants) and proceed through the various trophic levels (such as herbivores that eat plants, then carnivores that eat flesh, then omnivores that eat both plants and flesh, and so on). The highest level is the top of the food chain.

         iii      Structure of Atmosphere

The atmosphere can be divided into layers based on its temperature, as shown in the figure below. These layers are the troposphere, the stratosphere, the mesosphere and the thermosphere. A further region, beginning about 500 km above the Earth’s surface, is called the exosphere.

The Troposphere

This is the lowest part of the atmosphere – the part we live in. It contains most of our weather – clouds, rain, snow. In this part of the atmosphere the temperature gets colder as the distance above the earth increases, by about 6.5°C per kilometer.

The Stratosphere

This extends upwards from the troposphere to about 50 km. It contains much of the ozone in the atmosphere. The increase in temperature with height occurs because of absorption of ultraviolet (UV) radiation from the sun by this ozone.

The Mesosphere

The region above the stratosphere is called the mesosphere. Here the temperature again decreases with height, reaching a minimum of about -90°C at the “mesosphere “.

The Exosphere

The region above about 500 km is called the exosphere. It contains mainly oxygen and hydrogen atoms, but there are so few of them that they rarely collide – they follow “ballistic” trajectories under the influence of gravity, and some of them escape right out into space.

         iv      Koppen Climate Classification System

The Köppen climate classification system categorizes climate zones throughout the world based on local vegetation. Wladimir Köppen, a German botanist and climatologist, first developed this system at the end of the 19th century, basing it on the earlier biome research conducted by scientists. These scientists learned that vegetation and climate are intricately linked. The vegetation that grows in a region is dependent on the temperature and precipitation there, which are two key factors of climate. Areas with more rainfall and higher temperatures contain more forests while regions with less rainfall tend to be deserts. The Köppen climate classification system has been enhanced and modified several times since it was first published.

The system divides the world into five climate zones based on criteria, usually temperature, which allows for different vegetation growth. Köppen’s map used different colors and shades to represent the different climate zones of the world. While most of the zones are organized based on the temperature of a region, Zone B focuses on the aridity of a region. The zones are as follows:

Zone A: tropical or equatorial zone (represented by blue colors on most maps)

Zone B: arid or dry zone (represented by red, pink, and orange colors on most maps)

Zone C: warm/mild temperate zone (represented by green colors on most maps)

Zone D: continental zone (represented by purple, violet, and light blue colors on most maps)

Zone E: polar zone (represented by gray colors on most maps)

Each zone is further subdivided based on temperature or dryness.

1. 4 What is Positive and Negative Interaction? Explain them briefly with examples.

Most of the ecologists are in favour of the use of the term symbiosis, which literally means ‘living together’, in its broader sense. Odum (1971) used the term ‘symbiosis’ in its broader sense and preferred to group all the types of symbiotic interactions into two major groups. These are:

1. Positive Interactions

A type of interaction, where populations help one another, the interaction being either one-way or reciprocal. Their benefit may be in respect of food, shelter, substratum, transport etc. These include (i) commensalisms (ii) Protocooperation and (iii) Mutualism.

2. Negative Interactions

Where members of one population may live at the expense of members of the other population compete for foods, excrete harmful wastes, etc. These include

(i) Competition, (ii) Predation,  (iii) Parasitism, and (iv) Antibiosis.

Positive Interactions

1) Mutualism

Here both the species derive benefit. The two populations enter into some sort of physiological exchange. The following are some common examples of mutualism.

1. i) Symbiotic Nitrogen fixers

This is a well-known example of mutualism, where the bacterium Rhizobium form nodules in the roots of leguminous plants, and lives symbiotically with the host. Bacteria obtain food from the higher plant and in turn fix gaseous nitrogen, making it available to plant.

1. ii) Mycorrhizae

A symbiotic association between a fungus and a root of a higher plant is called Mycorrihza, which may be (i) Ectotrophic, where fungal hyphae are natural substitute of root hairs absorbing water and nutrients from soil e.g. Pines and Oaks or (ii) Endotrophic, where fungi occur internal to root tissue. e.g. Orchids and members of Ericaceae.

iii) Lichens

These are examples of mutualism where contact is close and permanent as well as obligatory. Their body is made up of a matrix formed by a fungus, within the cells of which an alga is embedded. Usually the fungal groups are from Ascomycetes or Busidiomycetes and the algal groups are species of blue greens. The algal groups takes up the photosynthetic function. The fungal groups are concerned with reproduction. The fungus makes moisture as well as minerals available, whereas alga manufactures food. Neither of the two can grow alone independently in nature. Lichens grow abundantly on bare rock surfaces.

 2) Commensalism:

Commensalism refers to association between members of different species only. One is benefited without any effect on the other. Some common examples are:

1. i) Lianes

 Lianes are common in dense forests of moist tropical climates. They maintain no direct nutritional relationship with the trees upon which they grow. On the basis of the type of device used for climbing their support, lianes may be leaners, thorn lianes, twiners or tendril lianes. Common lianes are species of Bauhinia, Ficus and Tinospora.

1. ii) Epiphytes

Epiphytes are plants growing perched on other plants. They use other plants only as support and not for water or food supply. They differ from lianes in that they are not rooted into the soil. Epiphytes may grow on trees, shrubs, or larger submerged plants. They grow either on the trunks or leaves. Epiphytes are most common in tropical rain forests. Many orchids, Usnea and Alectoria are well known epiphytes.

iii) Epizoics

Some plants grow on the surfaces of animals. For example, green algae grow on the long, grooved hairs of the sloth. Similarly,Basicladia (Cladophoraceae) grows on the backs of freshwater turtles.

Negative Interactions

These include the relations, in which one or both the species are harmed in any way during their life period. Some (Clarke, 1954) prefer to call such types of associations as ‘antagonism’. Such negative interactions are generally classified into three broad categories, as exploitation, antibiosis and competition which are discussed in detail as follows:

1. I) Exploitation

Here one species harms the other by making its direct or indirect use for support shelter, or food. Thus exploitation may be in respect of shelter or food.

1. Shelter

The so-called ‘parasitic birds’ as cuckoo and cowbird never build their own nests and female lays eggs in the nest established by birds of another usually smaller species.

2. Food

The various relationships in respect of food may belong to:

1. a) Parasitism

A parasite is the organism living on or in the body of another organism and deriving its food more or less permanently from its tissues.

There are some parasitic vascular plants. Species of Cuscuta (total stem parasites) grow on other plants on which they depend for nourishment. Young stem twines around the host stem from which adventitious roots develop that finally penetrate the stem of the host, establishing relationship with its conducting elements. The specialized roots are called haustoria.

1. b) Carnivorous Plants

A number of plants as Nepenthes, Darlingtonia, Drosera, Utricularia, Dionaea consume insects and other small animals for their foods. They are also known as insectivorous plants. They are adapted in remarkable ways to attract, catch and digest their victims. Their leaves or foliar appendages produce proteolytic enzymes for digestion of the insects. The carnivorous habit in plants is said to be an incidental feature of their nutrition, since they possess green leaves and carryout photosynthesis.

1. II) Antibiosis

The term ‘antibiosis’ generally refers to the complete or partial inhibition or death of one organism by another through the production of some substance or environmental conditions as a result of metabolic pathways. Here none of them derives any benefit. These substances and or conditions are harmful (antagonistic) to other organism. The phenomenon of antibiosis is much common among microbial world. Production of chemicals that are antagonistic to microbes – the antibiotics is well known.

Bacteria, actinomycetes and fungi produce a number of antimicrobial substances which are widespread in nature. Antagonistic substances are also reported in some algae, as for example in cultures of Chorella vulgaris, some substance accumulates which inhibits the growth of the diatom, Nitxschia frustrulum. Pond ‘blooms’ of blue-green algae especially Microcystis are known to produce toxins such as hydroxylamine which causes death of fish and cattle.

Competition

Competition occurs when individuals attempt to obtain a resource that is inadequate to support all the individuals seeking it, or even if the resource is adequate, individuals harm one another in trying to obtain it. The resources competed for can be divided into two types :

• Raw material such as light, inorganic nutrients, and water in autotrophs and organic food and water in heterotrophs.
• Space to grow, nest, hide from predators.

Q.5   Write down the categories and structure of Ecosystem in detail.

An ecosystem is a structural and functional unit of ecology where the living organisms interact with each other and the surrounding environment. In other words, an ecosystem is a chain of interactions between organisms and their environment. The term “Ecosystem” was first coined by A.G.Tansley, an English botanist, in 1935.

Structure of the Ecosystem

The structure of an ecosystem is characterized by the organization of both biotic and abiotic components. This includes the distribution of energy in our environment. It also includes the climatic conditions prevailing in that particular environment.

The structure of an ecosystem can be split into two main components, namely:

• Biotic Components
• Abiotic Components

The biotic and abiotic components are interrelated in an ecosystem. It is an open system where the energy and components can flow throughout the boundaries.

Biotic Components

Biotic components refer to all living components in an ecosystem.  Based on nutrition, biotic components can be categorised into autotrophs, heterotrophs and saprotrophs (or decomposers).

1. Producers include all autotrophs such as plants. They are called autotrophs as they can produce food through the process of photosynthesis. Consequently, all other organisms higher up on the food chain rely on producers for food.
2. Consumers or heterotrophs are organisms that depend on other organisms for food. Consumers are further classified into primary consumers, secondary consumers and tertiary consumers.

• Primary consumersare always herbivores as they rely on producers for food.
• Secondary consumersdepend on primary consumers for energy. They can either be carnivores or omnivores.
• Tertiary consumersare organisms that depend on secondary consumers for food.  Tertiary consumers can also be carnivores or omnivores.
• Quaternary consumers are present in some food chains. These organisms prey on tertiary consumers for energy. Furthermore, they are usually at the top of a food chain as they have no natural predators.
• Decomposers include saprophytes such as fungi and bacteria. They directly thrive on the dead and decaying organic matter.  Decomposers are essential for the ecosystem as they help in recycling nutrients to be reused by plants.

Abiotic Components

Abiotic components are the non-living component of an ecosystem.  It includes air, water, soil, minerals, sunlight, temperature, nutrients, wind, altitude, turbidity, etc.

Functions of Ecosystem

The functions of the ecosystem are as follows

• It regulates the essential ecological processes, supports life systems and renders stability.
• It is also responsible for the cycling of nutrients between biotic and abiotic components.
• It maintains a balance among the various trophic levels in the ecosystem.
• It cycles the minerals through the biosphere.

The abiotic components help in the synthesis of organic components that involve the exchange of energy.

So the functional units of an ecosystem or functional components that work together in an ecosystem are:

• Productivity –It refers to the rate of biomass production.
• Energy flow –It is the sequential process through which energy flows from one trophic level to another. The energy captured from the sun flows from producers to consumers and then to decomposers and finally back to the environment.
• Decomposition –It is the process of breakdown of dead organic material. The top-soil is the major site for decomposition.
• Nutrient cycling – In an ecosystem nutrients are consumed and recycled back in various forms for the utilization by various organisms.

Types of Ecosystem

An ecosystem can be as small as an oasis in a desert, or as big as an ocean, spanning thousands of miles. There are two types of ecosystem:

• Terrestrial Ecosystem
• Aquatic Ecosystem

Terrestrial Ecosystem

Terrestrial ecosystems are exclusively land-based ecosystems. There are different types of terrestrial ecosystems distributed around various geological zones. They are as follows:

• Forest Ecosystem
• Grassland Ecosystem
• Tundra Ecosystem
• Desert Ecosystem

Forest Ecosystem

A forest ecosystem consists of several plants, particularly trees, animals and microorganisms that live in coordination with the abiotic factors of the environment. Forests help in maintaining the temperature of the earth and are the major carbon sink.

Grassland Ecosystem

In a grassland ecosystem, the vegetation is dominated by grasses and herbs. Temperate grasslands and tropical or savanna grasslands are examples of grassland ecosystems.

Tundra Ecosystem

Tundra ecosystems are devoid of trees and are found in cold climates or where rainfall is scarce. These are covered with snow for most of the year. Tundra type of ecosystem is found in the Arctic or mountain tops.

Desert Ecosystem

Deserts are found throughout the world. These are regions with little rainfall and scarce vegetation. The days are hot, and the nights are cold.

Aquatic Ecosystem

Aquatic ecosystems are ecosystems present in a body of water. These can be further divided into two types, namely:

• Freshwater Ecosystem
• Marine Ecosystem

Freshwater Ecosystem

The freshwater ecosystem is an aquatic ecosystem that includes lakes, ponds, rivers, streams and wetlands. These have no salt content in contrast with the marine ecosystem.

Marine Ecosystem

The marine ecosystem includes seas and oceans. These have a more substantial salt content and greater biodiversity in comparison to the freshwater ecosystem.

The sun is the ultimate source of energy on earth. It provides the energy required for all plant life. The plants utilize this energy for the process of photosynthesis, which is used to synthesize their food.

During this biological process, light energy is converted into chemical energy and is passed on through successive trophic levels. The flow of energy from a producer, to a consumer and eventually, to an apex predator or a detritivore is called the food chain.

Dead and decaying matter, along with organic debris, is broken down into its constituents by scavengers. The reducers then absorb these constituents. After gaining the energy, the reducers liberate molecules to the environment, which can be utilized again by the producers.