The ecosystem can be divided, from the energetic view point into three types of organisms:
producers, consumers, and reducers. These can be explained as under:
Photosynthetic algae, plants and bacteria are the producers of the ecosystem; all other
organisms depend upon them directly or indirectly for food.
Consumers are herbivorous, carnivorous, and omnivorous animals; they eat the organic
matter produced by other organisms.
Decomposers are heterotrophic organisms like animals; they are fungi and bacterial that
Every living organism has to depend and interact with different nonliving or abiotic and living or biotic components of the environment.
The abiotic environmental components include basic inorganic elements and compounds such as water and carbon dioxide, calcium and oxygen, carbonates and phosphates besides physical factors such as soil, rainfall, temperature, moisture, winds, currents and solar radiation.
The biotic environmental factors comprise plants, animals, and microbes.
The scientific study of the interactions of organisms with their physical environment and with each other, is called ecology.
The eco-system can be defined as any spatial or organizational unit including living organisms and non-living substances interacting to produce an exchange of materials between the living and non-living parts. The eco-system can be studied from either structural or functional aspects.
1. Structural Aspect
The structural aspects of ecosystem include a description of the arrangement, types and
numbers of species and their life histories, along with a description of the physical features
of the environment.
2. Functional
The functional aspects of the ecosystem include the flow of energy and the cycling of
Endangered species in comprise of a variety of rare species of wild animals, aquatic animals and insects. Some of the endangered species in India are Himalayan wolf, crocodile nico barica, red panda, etc. Endangered species are of four types:
Endemic species are those species that are specific to a specific locality. It may also relate to a disease or pathogen that is confined to one particular area. One particular species endemic to India is the black buck.
Biodiversity is the degree of variation of life forms within a given species, ecosystem, etc. Biodiversity generally tends to cluster in hotspots. Biodiversity is commonly used to replace the more clearly defined and long established terms. Biologists define biodiversity as the totality of genes, species or ecosystem of a region.
Biodiversity is not evenly distributed. It varies greatly across the globe as well as within regions. Biodiversity is directly and indirectly related to human health as it provides support for drug discovery and is a valuable medicinal resource.
It plays a part in regulating the chemistry of our atmosphere and water supply. It is directly involved in water supply, recycling nutrients and providing fertile soil.
Habitat destruction in the form of deforestation of tropical forests has led to extinction of wildlife.
Write briefly about the biogeographical zones in India
There are 10 biogeographical zones in India. They are briefly described below:
1. Trans-Himmalayas: The Trans-Himmalayas is an extension of the Tibetean plateau.
2. Himalayas: The Himalayas form the northern boundary of India. The Himalayas comprises a diverse range of biotic provinces and biomes.
3. Desert: Three kinds of deserts are found in India. They are, Desert of western Rajasthan, Desert of Gujarat and the high altitude cold desert of Jammu & Kashmir and Himachal Pradesh
4. Semi-arid: This zone lies in between the desert and the Deccan plateau.
5. Western Ghats: This is a mountain range that runs along the western coast of India. This ghat section covers a diverse range of biotic provinces and biomes.
6. Deccan Plateau: It is a large triangular plateau south of Narmada valley. The Satpura mountains cover the north side, western ghats and eastern ghats cover the west and east sides respectively. The plateau slopes towards east. The plateau is covered with deciduous vegetation.
7. Gangetic plain: The Gangetic plains cover from south of the Himalayas to north of tropic of cancer. These plains were formed by the Ganges river system and are relatively homogenous. The famous 'sunderban' forests are located in these plains.
8. North-east India: The plains and non-himalayan hill ranges of northeastern India fall in this zone. This zone is filled with a wide variety of vegetation.
9. Islands: The Andaman and Nicobar islands in the bay-of-bengal is a group of 300 small and large islands. Mostly tribes live in Nicobar islands. These islands have a highly diverse set of biomes.
10. Coasts: The Indian subcontinent is blessed with a long coastline on the east and west with distinct differences between the two.
Write notes on threats to biodiversity
Biodiversity has evolved simultaneously with human culture. Man has met the changing needs and pressures of increasing population by applying knowledge and skills. People have hunted, fished and gathered species for food, fuel, fiber and shelter thereby eliminating competing or threatening species.
Activities mentioned above destroys and depletes the basis of an ecosystem (genes and species). As a result, mankind loses food, medicine and industrial products in the present and future.
According to the World Conservation Union's Red List, the threat to biodiversity is due to human activity particularly, habitat destruction.
Few of the Major biodiversity threats are listed below:
i. Habitat destruction
ii. Extension of agriculture
iii. Filling-up of wetlands
iv. Conversion of rich biodiversity site for human settlement and industrial development
v. Destruction of coastal areas
vi. Uncontrolled commercial exploitation
One of the primary causes of loss of biodiversity is habitat destruction. The main causes for the same are listed below:
i. Agricultural activities
ii. Extraction including mining, fishing, logging and harvesting
iii. Developmental activities including human settlement, industry and associated infrastructure
Millions of hectares of forest area is lost due to illegal encroachment of forest land. Forest land is also lost due to construction of river valley projects, introduction of transmission lines and roads, etc. Change in forest composition and quality can lead to decline in primary food species for wildlife.
Fragmentation is the process of division of a population into several small groups. Habitat loss and fragmentation leads to formation of isolated, small and scattered populations which are susceptible to inbreeding, depression, high infant mortality and eventually possible extinction.
Introduced species are responsible for many recorded species extinctions, especially on islands. In these isolated ecosystems, a new predator, competitor or pathogen can rapidly endanger species that did not evolve simultaneously with the newcomer.
Several forest, fisheries and wildlife resources have been over-exploited to the point of extinction. A few cases are mentioned below as a point in case. Poaching of wild animals (The Tiger, Elephant, Rhinoceros) has resulted in their extinction. Population pressures adversely affect the forest resources on which the local communities depend while having a negative impact on biodiversity.
Pollutants strain ecosystems. Contamination affects the food chain. A point in case is marine pollution from non-point sources that ruins estuaries and coastal seas throughout the world. Pesticides used to control agricultural pests have shown to negatively impact birds due to severe air pollution in Spain.
Write about energy flow in an ecosystem
Energy is an essential requirement for all living organisms. Solar energy is the only source of energy for the Earth. Solar energy is transformed to chemical energy by photosynthesis in plants (primary producers). Though lot of sunlight falls on plants, only 1% of this is utilized for photosynthesis.
Some amount of energy is used by the plant for growth and the remaining is transferred to consumers by the process of eating. Thus energy enters the ecosystem through photosynthesis and passes through different feeding levels (tropic levels)
The flow of energy through an ecosystem follows two laws of thermodynamics:
1. First law of thermodynamics states that “energy can neither be created nor destroyed, but can be converted from one form to another.” Ex: Energy for an ecosystem comes from the sun. It is absorbed by plants where it is converted and stored as chemical energy or solar energy is converted into chemical energy.
2. Second law of thermodynamics states that “whenever energy is transformed, there is a loss of energy through the release of heat.” Ex: Whenever energy is transferred between tropic levels, loss of energy takes place through respiration, running, hunting, etc.
Describe aquatic ecosystem
Aquatic ecosystem deals with water bodies. Types of organisms found in aquatic environment depend on salinity of water (salt content).
Types of aquatic life zones:
1. Fresh water life zones (Ponds, Streams, Rivers, Lakes)
2. Salt water life zones. (Oceans and Estuaries)
Pond ecosystems
i. Pond is temporary, only seasonal
ii. It is a stagnant freshwater body
iii. It is easily polluted due to limited amount of water.
Structure and function
Examples of abiotic components are temperature, light, water, organic and inorganic compounds.
Biotic components are comprised of
i. Producers: These include green photosynthetic organisms. They are of two types:
a) Phytoplankton and
b) Microphytes
Phytoplankton are microscopic aquatic plants, which float freely on the surface of water. Examples of phytoplankton are Algae, Volvox, Pandorina, Anabena and Cosmarium.
Microphytes are large floating plants and submerged plants. Examples of microphytes are hydrilla, jussiaea, wolfia and demna.
ii. Consumers:
Primary consumers (Zooplanktons): These are microscopic animals that freely float on the surface of water. Zooplanktons are found along with phytoplanktons which they eat. Examples of zooplanktons are planktons, very small fish, ciliates, flagellates and protozoans.
Secondary consumers (Carnivores): They feed on zooplanktons. Examples of carnivores are insects like water beetles and small fish.
Tertiary consumers: They feed on smaller fish. Examples of tertiary consumers are large fish like game fish.
iii. Decomposers: They decompose dead plant and animal matter and their nutrients are released and reused by green plants. Examples of decomposers are fungi, bacteria and flagellates.
Lake ecosystems:
i. Lakes are natural shallow water bodies
ii. Lakes are supplied with water from rainfall, melting snow and streams.
iii. Lake is a permanent water body with large water resources.
iv. Lakes help in irrigation and supplying drinking water.
Structure and function of Lake Ecosystem: The abiotic components of lake ecosystems consist of temperature, light, proteins, lipids, turbidity, oxygen and carbon-dioxide.
The biotic components are classified into:
i. Producers: Green plants (Floating, Submerged and amphibious). Examples of producers are phytoplanktons, algae and flagellates.
ii. Consumers: Primary consumers are zooplanktons like ciliates, protozoans, etc that feed on phytoplanktons.
Secondary consumers are carnivores like insects and smaller fishes that feed on zooplanktons
Tertiary consumers feed on smaller fish. Examples are large fish and game fish
iii. Decomposers: Decomposers decompose dead plants and animals. Examples of decomposers are bacteria, fungi and actinomycetes.
River Ecosystem:
i. It is fresh water and freely flowing water system
ii. Flowing water allows mixing of water resulting in higher dissolved oxygen
iii. River deposits large amount of nutrients.
Structure and function of River Ecosystem: The abiotic components of river ecosystems are temperature, light, pH, nutrients, organic and inorganic compounds.
Biotic components are classified into:
i. Producers: Phytoplankton, Algae, water grasses, aquatic grasses and other amphibious plants.
ii. Consumers: Primary consumers feed on phytoplanktons. Examples are water insects, snails and fishes.
Secondary consumers are feed on primary consumers.
iii. Decomposers: Decomposers decompose dead plants and animals. Examples of decomposers are bacteria, fungi and actinomycetes.
Ocean ecosystems:
i. Oceans occupy a large surface area and made up of saline water.
ii. Commercial activities are carried out in oceans.
iii. Oceans are rich in biodiversity
iv. Oceans moderate the temperature of the earth.
Structure and function of Ocean Ecosystems:
The abiotic components of ocean ecosystems are temperature, light, NaCl, K, Calcium and Magnesium salts and alkalinity.
The biotic components comprise of
i. Producers: Phytoplanktons (diatoms, unicellular algae, etc) and marine plants (sea weeds, chlorophyceal, phaeophyceae)
ii. Consumers: They are heterotrophic macroconsumers which depend upon producers for their nutrition.
a. Primary consumers or herbivores feed on producers (Ex: Crustaceans, Mollusks, Fish
b. Secondary consumers or carnivores feed on herbivores (Ex: Herring, Mackerel, etc)
c. Tertiary consumers are the top consumers and feed on small fishes. (Ex: Cod, Haddock, etc)
iii. Decomposers decompose dead organic matter. (Ex: Bacteria and fungi)
Estuarine ecosystem:
i. Estuaries are transition zones that are strongly affected by tides of the sea.
ii. Water in estuaries change periodically
iii. The organisms in estuaries have a wide tolerance
iv. Salinity remains highest in summer and lowest in winter.
Structure and function of Estuarine Ecosystems:
Abiotic components of estuarine ecosystems are temperature, pH, sodium and potassium salts and nutrients.
Biotic components consist of
i. Producers: Examples are marsh grasses, seaweeds, seagrasses and phytoplankton.
ii. Consumers: Examples are Oysters, Crabs, Seabirds, and small fishes
iii. Decomposers: Examples are Bacteria, fungi and actinomycetes.
Write in detail about structure and function of an ecosystem.
Ecology is the study of ecosystems and ecosystem is the basic functional unit of ecology. A group of organisms interacting amongst themselves and with the environment is called ecosystem. An ecosystem is a community of different species interacting with each other and their non-living environment thereby exchanging energy and matter.
Structure of an ecosystem shows the relationship between abiotic and biotic components.
All the living members of an ecosystem form the biotic community. Ex: Plants (producers), animals (consumers) and microorganisms (decomposers).
The non-living components (physical and chemical) of an ecosystem collectively form the abiotic community. Ex: Climate, Soil, Energy, Nutrients, Water and Air.
Physical components are necessary for the growth and maintenance of living components of the ecosystem.
Chemical components are the source for essential nutrients. They consist of organic substances (protein, lipids, carbohydrate) and inorganic substances (Al, Co, Zn, Cu-micro elements C, H, O, P, N, P, K-macro elements)
Function of an ecosystem is of three types:
Primary function: The primary function of all ecosystems is to manufacture starch (photosynthesis)
Secondary function: The secondary function of all ecosystems is to distribute energy to all the consumers in the form of food.
Tertiary function: All living organisms die and these dead systems are decomposed to initiate the third system of ecosystems called “cycling”.
Define and differentiate between food chain and food web with a diagram
A food chain is a model that shows the flow of energy from autotrophs to a series of organisms in an environment. The energy that flows can be different for each food chain. The food chain describes the flow of food from one organism to the next thereby giving energy to the organism digesting the food. The number of steps involved in a food chain is restricted to four or five. The energy available decreases with each step. The energy loss takes place in the form of heat. The three types of food chains are:
Grazing food chain,
Detritus food chain and
Parasitic food chain.
All food chains start with the sun.
The interlocking pattern of various food chains in an ecosystem is known as food web. In a food web many food chains are interconnected. In a food web different types of organisms are connected at different tropic levels resulting in several opportunities of eating and being eaten at each tropic level.
An important difference between food chain and food web is that food chain is linear and this implies that if one species becomes extinct, the species in the subsequent tropic levels are also affected. However, in a food web, if one species is affected, there is no serious effect on other tropic levels as there are several options available at each tropic level.
Enumerate the value of biodiversity
The value of biodiversity is classified into:
Direct values and
Indirect Values
Direct value of biodiversity: Biodiversity has direct value in the form of consumption in agriculture, medicine and industry. Among all plant species identified as fit for human consumption, only 150 have been cultivated on a large scale. Two types of direct values are:
Consumptive use value and
Productive use value
Consumptive use value is the value placed on nature's products that are consumed directly without passing through a market. Consumptive use value is not included in national income accounts. Consumptive use value benefits the communities closest to the resource if harvested sustainably with proper management. Product examples of consumptive use value are firewood, food and game meat.
Productive use value refers to products that are commercially harvested and sold in a market. Its value is estimated at production end after addition of cost and value. The productive use value has a major impact on national economy. Product examples of productive use value are timber, fish, honey, mushrooms, game meat sold in markets and medicinal plants.
Biodiversity has indirect value since it provides economic benefits without being harvested. Direct value of biodiversity is derived from its indirect value. Indirect value of biodiversity is listed below:
Non consumptive use value
Optional value
Existence value and
Information value
Non consumptive use value refers to nature's functions and services. Examples of this are photosynthesis by plants that provides support system for other species, maintenance of water cycle, regulating climate, production and protection of soil, absorption and breakdown of pollutants, recreational, aesthetic, socio-cultural, scientific, educational, spiritual and historic values of natural environments.
Option value refers to the indirect value of a species potential to produce economic benefits to the society in the future.
Existence value is the value gained from continuous knowledge of existence. An example in this context is the expense incurred by the administration of various countries to develop techniques in order to prevent a species from becoming extinct (Giant Panda, Blue whale, White tiger, etc).
Information value refers to the educational, scientific, aesthetic and tourism values of biodiversity in an ecosystem.
What are the types of biodiversity conservation
With the rapid increase of human population and resulting expansion of man's needs coupled with scientific knowledge led to over-exploitation of natural resources. Eventually, conservation of biological diversity became a global concern. This involves influencing behaviour of people at local level through education, at the national level through policy work and awareness programs. International corporations should ensure that their business do not contribute to further loss of biodiversity.
The two main types of biodiversity conservation are:
In-situ conservation and
Ex-situ conservation
In-situ conservation is defined as the conservation of genetic resources through their maintenance within natural or man-made ecosystems in which they occur.
In-situ conservation effort is setting-up of protection areas. This technique is the best conservation strategy. However, its implementation is sometimes unfeasible. National Parks, Sanctuaries and Biosphere reserves are some types of in-situ conservation.
Ex-situ conservation is defined as conservation made outside the habitat of an ecosystem. In case the habitat of rare or endangered species is destroyed, ex-situ conservation is the only means of conserving a species. It also provides a back-up solution to in-situ conservation projects. A few examples of ex-situ conservation are seed banks, botanical gardens, pollen storage, tissue culture and genetic engineering
