CBSE Class 11 Geography Biodiversity And Conservation Notes

CBSE Class XI Geography Biodiversity and Conservation Concepts. Learning the important concepts is very important for every student to get better marks in examinations. The concepts should be clear which will help in faster learning. The attached concepts made as per NCERT and CBSE pattern will help the student to understand the chapter and score better marks in the examinations.


This chapter deals with

• Ecology

 Types Of Ecosystem

Structure And Function Of Ecosystem

 Types Of Biomes

 Biogeochemical Cycles

 Water Cycles

 The Carbon Cycle

 Oxygen Cycle

 Nitrogen Cycle

Ecological Balance

Biodiversity as we have today is the result of 2.5-3.5 billion years of evolution. Before the advent of humans, our earth supported more biodiversity than in any other period. Since, the emergence of humans, however, biodiversity has begun a rapid decline, with one species after another bearing the brunt of extinction due to overuse. The number of species globally vary from 2 million to 100 million, with 10 million being the best estimate. New species are regularly discovered most of which are yet to be classified (an estimate states that about 40 per cent of fresh water fishes from South America are not classified yet). Tropical forests are very rich in bio-diversity Biodiversity is a system in constant evolution, from a view point of species, as well as from view point of an individual organism.

The average half-life of a species is estimated at between one and four million years, and 99 per cent of the species that have ever lived on the earth are today extinct.

Biodiversity is not found evenly on the earth. It is consistently richer in the tropics. As one approaches the polar regions, one finds larger and larger populations of fewer and fewer species.

Biodiversity itself is a combination of towards, Bio (life) and diversity (variety). In simple terms, biodiversity is the number and variety of organisms found within a specified geographic region. It refers to the varieties of plants, animals and micro-organisms, the genes they contain and the ecosystems they form. It relates to the variability among living organisms on the earth, including the variability within and between the species and that within and between the ecosystems.


(i)Genetic diversity;

(ii)Species diversity;

(iii)Ecosystem diversity.

Genetic Diversity

Genetic biodiversity refers to the variation of genes within species. Groups of individual organisms having certain similarities in their physical characteristics are called species. Human beings genetically belong to the homo sapiens group and also differ in their characteristics such as height, colour, physical appearance, etc., considerably. This is due to genetic diversity. This genetic diversity is essential for a healthy breeding of population of species.

Species Diversity

This refers to the variety of species. It relates to the number of species in a defined areaThe diversity of species can be measured through its richness, abundance and types. Some areas are more rich in species than others. Areas rich in species diversity are called hotspots of diversity

Ecosystem Diversity

The broad differences between ecosystem types and the diversity of habitats and ecological processes occurring within each ecosystem type constitute the ecosystem diversity.                                                                                        The ‗boundaries‘ of communities (associations of species) and ecosystems are not very rigidly defined. Thus, the demarcation of ecosystem boundaries is difficult and complex.

Importance of Biodiversity

1. Biodiversity has contributed in many ways to the development of human culture In turn, human communities have played a major role in shaping the diversity of nature at the genetic, species and ecological levels.

Biodiversity plays the following roles:

1. ecological ,         2. economic         3. scientific.

2. Species of many kinds perform some function or the other in an ecosystem. Nothing in an ecosystem evolves and sustains without any reason.

3. That means, every organism, besides extracting its needs, also contributes something of useful to other organisms.

4. Species capture and store energy, produce and decompose organic materials, help to cycle water and nutrients throughout the ecosystem, fix atmospheric gases and help regulate the climate.

5. These functions are important for ecosystem function and human survival.

6. The more diverse an ecosystem, better are the chances for the species to survive through adversities and attacks, and consequently, is more productive.

7.the more the variety of species in an ecosystem, the more stable the ecosystem is likely to be.

Economic Role of Biodiversity

1. ‗crop diversity‘, which is also called agro-biodiversity.

2. Biodiversity is seen as a reservoir of resources to be drawn upon for the manufacture of food, pharmaceutical, and cosmetic products.

3. This concept of biological resources is responsible for the deterioration of biodiversity.

4. At the same time, it is also the origin of new conflicts dealing with rules of division and appropriation of natural resources.

5. Some of the important economic commodities that biodiversity supplies to humankind are: food crops, livestock, forests, fish, medicinal resources, etc.

Scientific Role of Biodiversity

1. Biodiversity is important because each species can give us some clue as to how life evolved and will continue to evolve.

2. Biodiversity also helps in understanding how life functions and the role of each species in sustaining ecosystems of which we are also a species.

3. This fact must be drawn upon every one of us so that we live and let other species also live their lives.

4. The level of biodiversity is a good indicator of the state of our relationships with other living species. In fact, the concept of biodiversity is an integral part of many human cultures.


Tropical regions which occupy only about one-fourth of the total area of the world, contain about three fourth of the world human population. Over exploitation of resources and deforestation have become rampant to fulfill the needs of large population. Tropical rain forests contain 50 per cent of the species on the earth. Destruction of natural vegetation have proved disastrous for the entire biosphere.

1. Natural calamities such as earthquakes, floods, volcanic eruptions, forest fires, droughts, etc. cause damage to the flora and fauna of the earth, bringing change the biodiversity of respective affected regions.

2. Pesticides and other pollutants such as hydrocarbons and toxic heavy metals destroy the weak and sensitive species.

3. Species which are not the natural inhabitants of the local habitat but are introduced into the system, are called exotic species.       There are many examples when a natural biotic community of the ecosystem suffered extensive damage because of the introduction of exotic species.

During the last few decades, some animals like tigers, elephants, rhinoceros, crocodiles, minks and birds were hunted mercilessly by poachers for their horn, tusks, hides, etc. It has resulted in the rendering of certain types of organisms as endangered category. The International Union of Conservation of Nature and Natural Resources (IUCN) has classified the threatened species of plants and animals into three categories for the purpose of their conservation.

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