Class 12 Swadesh Adhyayan Chapter 3 Biodiversity

Class 12 Swadesh Adhyayan Chapter 3 Biodiversity, Class 12 Question Answer to each chapter is provided in the list of AHSEC so that you can easily browse through different chapters and select needs one. Class 12 Swadesh Adhyayan Chapter 3 Biodiversity Question Answer can be of great value to excel in the examination.

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Class 12 Swadesh Adhyayan Chapter 3 Biodiversity Notes covers all the exercise questions in HS 2nd Year Swadesh Adhyayan Textbooks Solutions. The Assam Board Class 12 Swadesh Adhyayan Chapter 3 Biodiversity provided here ensures a smooth and easy understanding of all the concepts. Understand the concepts behind every chapter and score well in the board exams.


Chapter – 3


1. What do you mean by Biodiversity? What are its various types? Explain citing suitable examples.

Ans. The word Biodiversity is a contraction of the phrase ‘biological diversity’. It refers to the variety and variability of species on earth. Biodiversity encompasses from the microorganisms, animals, plants to ecosystems like coral reefs, grasslands etc. It also refers to the number one abundance of different species living within a particular region. The amount of biodiversity in any place is therefore be seen as a result of the complex interaction of these factor.

The 1992 United Nations Earth Summit held in Rio de Janeiro defined ‘biological diversity’ as “the variability among living organisms from all sources, including inter alia, terrestrial, marine and other aquatic ecosystems and the ecological complexes of which they are part: this includes diversity within species, between species and of ecosystems”.

Scientists have recognised primarily three types of biodiversity. 

These one explained below citing suitable examples – 

(a) Species Diversity: Species Diversity is the number of different species that are represented in a given community. It consists of three components: species richness, taxonomic or phylogenetic diversity and species evenness. Therefore it is the variety and abundance of species. Diversity is greatest when all the species present are equally abundant in the area. For example – woodland forest comprising 5-6 different species of trees, variety of fishes in a river stream etc.

(b) Genetic Diversity: Genetic diversity refers to the diversity within species. It is the total number of genetic characteristics in the genetic makeup of a species. The term genetic diversity also covers distinct populations of a single species, such as the thousands of breeds of different dogs or the numerous variety of roses.

(c) Ecosystem Diversity: Ecosystem diversity is the variation in the ecosystems found in a region or the variation in ecosystems over the whole planet. It includes the variation in both terrestrial and aquatic ecosystems and can also take into account the variation in the complexity of a biological community. An example of ecological diversity on a global scale would be the variation in ecosystems, such as deserts, forests, grasslands, wetlands and oceans.

Besides there above mentioned bio diversity, Campbell in 2003 added another diversity, i.e.

(d) Molecular Biodiversity: Molecular biodiversity depends on inheritable DNA and occurs within one individual, between individual of the same species, between related species, within and between phyla and ecosystems and throughout evolution. Without molecular biodiversity evolution cannot occur, either in the origin of a new species, its survival and development, on its eventual extinction.

2. How can we measure biodiversity? Describe its different procedures. 

Ans. Biodiversity can be measured in relation to the two components of it i.e. species richness and evenness. Richness is a measure of how many organism exist in a given area and Evenness refers to how close in number each species in an environment is. A variety of mathematical techniques have been developed to measure biodiversity, but it is often most convenient for a scientist to use an index that can represent both richness and abundance.

The different procedures to measure biological diversity are described below – 

(a) Diversity Indices: A diversity index is a mathematical measure of species diversity in a given community. This measure is based on the species richness (the no. of species present) and species abundance (the no. of individuals per species), of an area. The more species it have, the more diverse the area. Generally there are two types of indices 1. Dominance indices and 2. Information statistic indices. To measure dominance indices we are Simpson index and to measure information statistic indices we are Shannon index.

(b) Alpha diversity: Another way to measure diversity is the Alpha diversity. It refers to the numbers of species in a single community at a particular time. Alpha diversity can also be called as species richness and is used to compare a no. of species in different communities.

(c) Beta diversity: It is the measure of the degree of change in species composition along with an environment gradient. For eg. Beta diversity is high if the species composition of mass communities changes successively at higher elevation on a mounting slope. Beta diversity is low if the same species of mass occupy the whole mountainside.

(d) Gamma Diversity: Gamma diversity is the rate at which additional species are encountered as a geographical replacement within a habitat type in different localities. It is a species turnover rate with the distance between sites of similar habitat or with expanding geographical areas.

The four procedures to measure and explain biodiversity are briefly discussed above.

3. Prepare a note on the biodiversity of Assam.

Ans. Assam with its unique location, amidst state of north east India, physiographical diversity like mountains, flood plain, rivers and marches and plateaus, etc., is one of the rich biodiversity states in India. It is one of the two biodiversity hotpots that are in India, i.e. Western Ghats biodiversity Hotspot and Northeast India. 

Some of the important characteristics of biodiversity in Assam are – 

1. Abundance of forest.

2. Wetland ecosystem.

3. The network of River Brahmaputra and its tributaries.

4. Grassland ecosystem and

5. National park and Sanctuaries.

Unique physiography, favourable geographical location, diverse topography, ideal climatic conditions, large floodplain wetlands, swamps and the riven Brahmaputra helps Assam to harbour a rich biodiversity. Assam have recorded 42 species of Bamboo, 193 species of orchids, 164 species of mammals. 950 species of birds, 1 species of crocodilian , 19 species of Turtles and Tortoise, 77 species of Squamata, 70 species of amphibian, 185 Species of fish, 10 species of Molluscs and approximately 405 species of Butterflies and 347 species of moths so far.

Due to the presence of such varieties of Flora and Fauna, Assam becomes a rich biodiversity State in India.

4. Explain about the problem and prospects of biodiversity of Assam.

Ans. Assam although being a rich biodiversity state in India, and identified as one of the diverse region of the world, has been facing a severe threat to its resources due to unplanned development, anthropogenic activities, urbanisation, unconsciousness etc. And due to such reasons, the traditional rich Knowledge on biodiversity as well as conservation measures has been decreasing at a very faster and alarming rate. The problem of conservation need to be addressed as soon as possible to arrest the decreasing biodiversity trends. 

Some of the identified problems of biodiversity in Assam are – 

(a) Population growth and density.

(b) Habitat destruction by anthropogenic causes.

(c) Overgrazing.

(d) Poaching.

(e) Bio piracy. 

(f) flood and bank erosion.

(g) Application of agro-chemicals. and 

(h) Loss of traditional technology.  

However, despite the problem identified this rich biodiversity region also provides the state with scope for economic progress and development some of the areas which show promise are- 

(a) Ecotourism.         

(b) Fish production.             

(c) Ornamental fish.

(d) Bamboo-based industries.    

(e) Traditional food and medicine.

(f) Traditional knowledge research 

(g) Prospect of tourism infrastructure.

5. Prepare a note on the need of conservation of biodiversity. 

Ans. Due to constant human intervention, the resources that are on the earth are decreasing day by day. Most particularly the natural resource are not found uniformity and we have long ago crossed the carrying capacity of the mother earth. It is therefore, felt globally to conserve our resource and wildlife or biodiversity. It mean the judicious and planned use as well as reuse of natural resources by avoiding their wastage, misuse and overuse. Since our survival depends on the availability of resources like food medicine, materials, water supply etc., therefore the conservation of biodiversity is a must. Since the damage to biodiversity is irreversible, so there is a constant need for biodiversity conservation so that mother earth can maintain the diversity of organism ecological complexity, which help in the evolution of species and thereby reducing extinction of population and species.

6. What is pollution? Explain it various types. 

Ans. Pollution is the introduction of contaminants into the natural environment at a rate faster than it can be safely stored. The term pollution can refer to both artificial and natural materials that are created, consumed and discarded in an unsustainable manner that causes adverse changes to the environment.

Although, pollution can be divided into many types, some of the major types of pollutions are- 

(a) Air Pollution: It is the release of chemicals and particulates into the atmosphere through various human and natural activities like , smoke from factories , bon-fire, volcanic eruption, etc. Common gaseous pollutants include carbon mono-oxide, sulphur dioxide, chlorofluorocarbons, CFC and nitrogen oxides produced by industry and motor vehicles.

(b) Water Pollution: It occurs by the discharge of waste water from commercial and industrial waste into surface water, discharge of untreated domestic sewage and chemical contaminants such as chlorine into surface runoff flowing to surface water.

(c) Soil Contamination: It occurs when chemicals are released by spilt on underground leakage. Among the most significant soil contaminants are hydrocarbons, heavy metals, herbicides, pesticides, and chlorinated hydrocarbon. 

(d) Noise Pollution: It encompasses roadway noise, aircraft noise, industrial noise as well as high-intensity sonar.

(e) Plastic Pollution: It involves the accumulation of plastic products and micro plastics in the environment that adversely affect wildlife, wildlife habitat and human.

(f) Radioactive Contamination: It is the result from 20th century activities in atomic physics such as nuclear power generation and nuclear weapon research and development.

7. What is sustainable development? Explain the development of the concept of sustainable development?

Ans. Sustainable development is development that meets the needs of the present generations without compromising the ability of future generation to meet their own needs. It is the use of resources in such a way that ensure we have sufficient resources for the future.

The concept of sustainable development formed the basis of the United Nations Conference on Environment and Development held in Rio de Janeiro in 1992. The summit marked the first international attempt to draw up action plans and strategies for moving towards a more sustainable pattern of development. The term was popularised later in ‘Our Common Future’ (Brundtland Report 1987) the report of the world Commission on Environment and Development. Most recently, In September 2015, the General Assembly of the United Nations Organisation has adopted the Agenda for Sustainable Development that includes 17 Sustainable Development Goals (SDG) to be realised by 2030. Five SDGs of 17 to transform our world are – no poverty, zero hunger, quality education, gender equality and good health. The goals are nicely crafted and aims to remove many evils of human society.

The concept of sustainable development has developed very much from its initial emergence and at present it is a major issue for the entire world.


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