NCERT Solution Biodiversity and Conservation class 12

Biodiversity and Conservation class 12 NCERT Solution Chapter 15 Explanation Question and Answer

Biodiversity and Conservation class 12 taken from NCERT Book Biology Chapter 15 In this chapter we covered all the Important Topics related to this chapter.

Biodiversity and Conservation class 12

Biodiversity and Conservation class 12 Introduction

If an alien from a distant galaxy were to visit our planet Earth, the first thing that would amaze and baffle him would most probably be the enormous diversity of life that he would encounter.

Even for humans, the rich variety of living organisms with which they share this planet never ceases to astonish and fascinate us. The common man would find it hard to believe that there are more than 20,000 species of ants, 3,00,000 species of beetles, 28,000 species of fishes, and nearly 20,000 species of orchids.

Ecologists and evolutionary biologists have been trying to understand the significance of such diversity by asking important questions– Why are there so many species? Did such great diversity exist throughout Earth’s history? How did this diversification come about? How and why is this diversity important to the biosphere? Would it function any differently if the diversity was much less? How do humans benefit from the diversity of life?

Biodiversity and Conservation class 12 Definition

Diversity and conservation, at its core, means the diversity of life on Earth and efforts to preserve and protect it. It includes species diversity, environmental diversity, and genetic diversity among species. Environmental policies aimed at nature conservation, biodiversity conservation and restoration, conservation, wildlife management, sustainable use of resources, and risk reduction

Biodiversity and Conservation class 12 Important Notes

The importance of biodiversity: Diversity is essential to maintain the stability, resilience, and function of ecosystems. It provides ecosystem services such as air and water purification, pollination, nutrient cycling, and climate control.

Threats to Biodiversity: Human activities such as habitat destruction, destruction, contamination, pollution, over-exploitation of natural resources, the introduction of insect diseases, and climate change are threats to biodiversity as well as the rest of the world.

Conservation strategies: Conservation strategies focus on the conservation and sustainable management of biodiversity at local, regional, and global levels. These projects include habitat protection, protected areas (such as national parks and nature reserves), breeding programs, infrastructure rehabilitation, land use for sustainability, and conservation projects developed by local communities.

Role of governments and international organizations: Governments play an important role in creating laws and regulations for biodiversity conservation, establishing protected areas, and implementing nature conservation programs. International organizations such as the United Nations Environment Program (UNEP) and the Convention on Biological Diversity (CBD) facilitate international cooperation and cooperation in biodiversity conservation.

In situ and ex-situ conservation: In situ, conservation will protect animals and ecosystems in their habitats, while ex-situ conservation will protect animals outside their habitats, such as in zoos, nurseries, seed banks, and closed programs.

Sustainable Development: Achieving sustainable development requires a balance between economic growth, social justice, and environmental management. Conservation efforts must be combined with sustainable development goals to ensure the long-term health of people and the natural environment.

Community engagement: Engaging local communities in conservation is critical to strengthening environmental governance, promoting sustainable livelihoods, and building support for conservation.

Education and awareness: Raising awareness of the importance of biodiversity conservation through education, presentations, and social media is important for public support and behavior change.

Biodiversity and Conservation class 12 Explanation


In our biosphere, immense diversity (or heterogeneity) exists not only at the species level but at all levels of biological organization ranging from macromolecules within cells to biomes. Biodiversity is the term popularized by the sociobiologist Edward Wilson to describe the

Combined diversity exists at all levels of biological organization. The most important of them are:

(i) Genetic diversity: This refers to the variation in genes within a species. For example, the medicinal plant Rauwolfia vomitoria may exhibit genetic diversity in terms of the potency and concentration of the active chemical it produces. India boasts over 50,000 genetically distinct strains of rice and 1,000 varieties of mango.

(ii) Species diversity: This pertains to the variety of species within a particular ecosystem. For instance, the Western Ghats exhibit greater amphibian species diversity compared to the Eastern Ghats.

(iii) Ecological diversity: This refers to the diversity of ecosystems within a region. India, for example, encompasses diverse ecosystems such as deserts, rainforests, mangroves, coral reefs, wetlands, estuaries, and alpine meadows, surpassing the ecosystem diversity of countries like Norway.

It has taken millions of years for nature to accumulate such rich diversity, but we risk losing it in a fraction of that time if current rates of species loss persist. Biodiversity and its conservation have become vital environmental concerns globally as people increasingly recognize its critical importance for our survival and well-being.

How Many Species are there on Earth and How Many in India?

While published records document all discovered and named species, estimating the total number of species on Earth remains challenging. The International Union for Conservation of Nature (IUCN) reports slightly more than 1.5 million described plant and animal species, but

the number of undiscovered species remains uncertain. Estimates of total species range from 20 to 50 million, with a more conservative estimate by Robert May placing global species diversity at about 7 million.

Many undiscovered species are believed to exist, especially in tropical regions, where species inventories are less complete compared to temperate regions. Biologists use statistical comparisons of temperate-tropical species richness to extrapolate estimates of total species diversity.

Let us look at some interesting aspects about Earth’s biodiversity based on the currently available species inventories. More than 70 percent of all the species recorded are animals, while plants (including algae, fungi, bryophytes, gymnosperms, and angiosperms) comprise no more than 22 percent of the total.

Among animals, insects are the most species-rich taxonomic group, making up more than 70 percent of the total. That means, out of every 10 animals on this planet, 7 are insects.

Again, how do we explain this enormous diversification of insects? The number of fungi species in the world is more than the combined total of the species of fishes, amphibians, reptiles, and mammals. In Figure 15.1, biodiversity is depicted showing the species number of major taxa.

Biodiversity and Conservation class 12

Although India has only 2.4 percent of the world’s land area, its share of the global species diversity is an impressive 8.1 percent. That is what makes our country one of the 12 mega-diversity countries of the world.

Nearly 45,000 species of plants and twice as many of animals have been recorded from India. How many living species are actually there waiting to be discovered and named? If we accept May’s global estimates, only 22 percent of the total species have been recorded so far.

Applying this proportion to India’s diversity figures, we estimate that there are probably more than 1,00,000 plant species and more than 3,00,000 animal species yet to be discovered and described.

Would we ever be able to complete the inventory of the biological wealth of our country? Consider the immense trained manpower (taxonomists) and the time required to complete the job. The situation appears more hopeless when we realize that a large fraction of these

species faces the threat of becoming extinct even before we discover them. Nature’s biological library is burning even before we cataloged the titles of all the books stocked there.

15.1.2 Patterns of Biodiversity

(i) Latitudinal gradients: The diversity of plants and animals is not uniform throughout the world but shows a rather uneven distribution. For many groups of animals or plants, there are interesting patterns in diversity, the most well-known being the latitudinal gradient in diversity.

In general, species diversity decreases as we move away from the equator towards the poles. With very few exceptions, the tropics (latitudinal range of 23.5° N to 23.5° S) harbor more species than temperate or polar areas.

Colombia located near the equator has nearly 1,400 species of birds while New York at 41° N has 105 species and Greenland at 71° N only 56 species. India, with much of its land area in the tropical latitudes, has more than 1,200 species of birds.

Biodiversity and Conservation class 12

A forest in a tropical region like Ecuador has up to 10 times as many species of vascular plants as a forest of equal area in a temperate region like the Midwest of the USA. The largely tropical Amazonian rainforest in South America has the greatest biodiversity on earth- it is home to more than 40,000 species of plants, 3,000 of fishes, 1,300 of birds, 427 of mammals, 427 of amphibians, 378 reptiles, and more than 1,25,000 invertebrates.

Scientists estimate that in these rainforests there might be at least two million insect species waiting to be discovered and named.

evolutionary time for species diversification, (b) Tropical environments, unlike temperate ones, are less seasonal, relatively more constant, and predictable.

Such constant environments promote niche specialization and lead to greater species diversity, and (c) There is more solar energy available in the tropics, which contributes to higher productivity; this, in turn, might indirectly contribute to greater diversity.

(ii) Species-Area relationships: During his pioneering and extensive explorations in the wilderness of South American jungles, the great German naturalist and geographer Alexander von Humboldt observed that within a region species richness increased with increasing explored area, but only up to a limit.

In fact, the relation between species richness and area for a wide variety of taxa (angiosperm plants, birds, bats, freshwater fishes) turns out to be a rectangular hyperbola (Figure 15.2).


  • S represents species richness.
  • A represents area.
  • Z is the slope of the line (regression coefficient).
  • C is the y-intercept.

regardless of the taxonomic group or the region (whether it is the plants in Britain, birds in California, or mollusks in New York state, the slopes of the regression line are amazingly similar).

But, if you analyze the species-area relationships among very large areas like the entire continents, you will find that the slope of the line to be much steeper (Z values in the range of 0.6 to 1.2). For example, for frugivorous (fruit-eating) birds and mammals in the tropical forests of different continents, the slope is found to be 1.15. What do steeper slopes mean in this context?

15.1.3 The Importance of Species Diversity to the Ecosystem

Does the number of species in a community really matter to the functioning of the ecosystem? This is a question for which ecologists have not been able to give a definitive answer.

For many decades, ecologists believed that communities with more species, generally, tend to be more stable than those with fewer species. What exactly is stability for a biological

Community stability is characterized by minimal variation in productivity from year to year, resistance or resilience to disturbances, whether natural or human-induced and resistance to invasions by alien species.

While the precise relationship between species richness and these attributes remains unclear, David Tilman’s long-term ecosystem experiments offer some insights. Tilman observed that plots with higher species diversity exhibited less year-to-year variation in total biomass and higher productivity.

Although the complete contribution of species richness to ecosystem well-being is not fully understood, it is evident that rich biodiversity is crucial not only for ecosystem health but also for the survival of humanity.

As species disappear at an alarming rate, questions arise: Does the extinction of a few species truly matter? Would the functionality of Western Ghats’ ecosystems be compromised if a tree frog species were lost forever? How does our quality of life change if, for example, the number of ant species drops from 20,000 to 15,000?

While direct answers to such questions may be elusive, Stanford ecologist Paul Ehrlich offers an analogy—the ‘rivet popper hypothesis’. In an ecosystem, every species acts like a rivet holding an airplane together.

Initially, the removal of a few rivets may not impact flight safety (ecosystem functioning). However, as more rivets are lost, the ecosystem weakens, with certain species playing critical roles akin to rivets on the wings

Biodiversity and Conservation class 12

Loss of Biodiversity

While new species are unlikely to be added to Earth’s species inventory through speciation, there is no doubt about the ongoing losses.

Human activities are largely responsible for the rapid decline in the planet’s biological wealth. Human colonization of tropical Pacific Islands, for instance, has led to the extinction of over 2,000 species of native birds.

The IUCN Red List (2004) documents the extinction of 784 species over the last 500 years, including vertebrates, invertebrates, and plants. Recent extinctions include the dodo, quagga, thylacine, Steller’s Sea Cow, and various tiger subspecies.

In the last twenty years alone, 27 species have disappeared. Careful analysis of records highlights the dire consequences of human-induced biodiversity loss.

shows that extinctions across taxa are not random; some groups like amphibians appear to be more vulnerable to extinction. Adding to the grim scenario of extinction is the fact that more than 15,500 species worldwide are facing the threat of extinction.

Presently, 12 percent of all bird species, 23 percent of all mammal species, 32 percent of all amphibian species, and 31 percent of all gymnosperm species in the world face the threat of extinction.

From a study of the history of life on Earth through fossil records, we learn that large-scale loss of species like the one we are currently witnessing has also happened earlier, even before humans appeared on the scene.

During the long period (> 3 billion years) since the origin and diversification of life on Earth, there were five episodes of mass extinction of species. How is the ‘Sixth Extinction’ presently in progress different from the previous episodes?

The difference lies in the rates; the current species extinction rates are estimated to be 100 to 1,000 times faster than in the pre-human times, and our activities are responsible for the faster rates. Ecologists warn that if the present trends continue, nearly half of all the species on Earth might be wiped out within the next 100 years.

In general, loss of biodiversity in a region may lead to (a) decline in plant production, (b) lowered resistance to environmental perturbations such as drought, and (c) increased variability in certain ecosystem processes such as plant productivity, water use, and pest and disease cycles.

Causes of biodiversity losses: The accelerated rates of species extinctions that the world is facing now are largely due to human activities. There are four major causes (‘The Evil Quartet’ is the sobriquet used to describe them).

(i) Habitat loss and fragmentation: This is the most important cause driving animals and plants to extinction. The most dramatic examples of habitat loss come from tropical rainforests. Once covering more than 14 percent of the Earth’s land surface, these rainforests now cover no more than 6 percent.

They are being destroyed fast. By the time you finish reading this chapter, 1000 more hectares of rainforest would have been lost. The Amazon rainforest (it is so huge that it is called the ‘lungs of the planet’)

harboring probably millions of species is being cut and cleared for cultivating soya beans or for conversion to grasslands for raising beef cattle. Besides total loss, the degradation of many habitats by pollution also threatens the survival of many species.

When large habitats are broken up into small fragments due to various human activities, mammals and birds requiring large territories and certain animals with migratory habits are badly affected, leading to population declines.

(ii) Over-exploitation: Humans have always depended on nature for food and shelter, but when ‘need’ turns to ‘greed’, it leads to

Biodiversity and Conservation class 12 summary

Since life originated on Earth nearly 3.8 billion years ago, there has been enormous diversification of life forms on the planet.

Biodiversity refers to the sum total of diversity that exists at all levels of biological organization. Of particular importance is the diversity at genetic, species, and ecosystem levels, and conservation efforts are aimed at protecting diversity at all these levels.

More than 1.5 million species have been recorded in the world, but there might still be nearly 6 million species on Earth waiting to be discovered and named. Of the named species, over 70 percent are animals, of which 70 percent are insects.

The group Fungi has more species than all the vertebrate species combined. India, with about 45,000 species of plants and twice as many species of animals, is one of the 12 mega diversity countries of the world.

Species diversity on Earth is not uniformly distributed but shows interesting patterns. It is generally highest in the tropics and decreases towards the poles. Important explanations for the species richness of the tropics include:

Tropics had more evolutionary time; they provide a relatively constant environment, and they receive more solar energy, which contributes to greater productivity. Species richness is also a function of the area of a region; the species-area relationship is generally a rectangular hyperbolic function.

It is believed that communities with high diversity tend to be less variable, more productive, and more resistant to biological invasions. Earth’s fossil history reveals incidences of mass extinctions in the past, but the present rates of extinction, largely attributed to human activities, are 100 to 1000 times higher.

Nearly 700 species have become extinct in recent times, and more than 15,500 species (of which over 650 are from India) currently face the threat of extinction. The causes of high extinction rates at present include habitat (particularly forests) loss and fragmentation, overexploitation, biological invasions, and co-extinctions.

Earth’s rich biodiversity is vital for the very survival of mankind. The reasons for conserving biodiversity are narrowly utilitarian, broadly utilitarian, and ethical. Besides the direct benefits (food, fiber, firewood, pharmaceuticals, etc.),

there are many indirect benefits we receive through ecosystem services such as pollination, pest control, climate moderation, and flood control. We also have a moral responsibility to take good care of Earth’s biodiversity and pass it on in good order to our next generation

Biodiversity and Conservation class 12 Important Question and Answer

Question:1 What are the 4 types of biodiversity?


Genetic Diversity: This refers to genetic variation within a species. It covers the different alleles, variants and genetic traits found in a population of a species.

Species diversity: This refers to the number of individuals living in an area or ecosystem. It includes the number of species present and their abundance.

Ecosystem diversity: This refers to the diversity of organisms, ecosystems, and ecological processes in an area. It includes various ecosystems such as forests, grasslands, rivers, deserts and aquatic environment.

Functional diversity: This refers to the diversity of different biological functions and ecological processes within an ecosystem. It encompasses the many roles that organisms play in maintaining ecosystem functions, such as cycling, pollination, decomposition, and predator-prey interactions.

Question:2 What are the types of ecosystems?


  1. Forest Ecosystem.
  2. Grassland Ecosystem.
  3. Tundra Ecosystem.
  4. Desert Ecosystem.

Question:3 What are the 6 major ecosystems?


  1. Forests
  2. Grasslands
  3. Deserts
  4. Tundra
  5. Aquatic (Freshwater)
  6. Marine

Question:4 What is the significance of the slope of regression in a species–area


Rate of species accumulation: A steep slope shows that species richness increases rapidly as the area increases. Conversely, shallowness indicates a gradual increase in species diversity.

Comparative analysis: Distribution allows comparison of species and area relationships in different habitats or geographic areas. It focuses on biodiversity and the ecological dynamics of different ecosystems.

Conservation Assessment: Identifying fragmentation helps predict the impact of habitat loss or fragmentation on biodiversity. Damage or destruction of mountainous habitats can increase the risk of biodiversity loss.

Management and restoration: Conservation efforts can be characterized by the spatial interactions of species. More intensive conservation measures may be needed to protect and maintain the high biodiversity in areas with steep slopes.

Ecological Theory: The field of species interactions contributes to ecological theory and the understanding of species distribution patterns, community dynamics, and island biogeography.

Question:5 What are sacred groves? What is their role in conservation?


Sacred forests are forest areas of cultural, religious and spiritual importance to local communities. These gardens are found in many parts of the world. and are respected and protected by the community. Because it is related to gods, ancestors, or traditional beliefs. One of the most important functions of sacred forests is to maintain biodiversity. diversity.

Sacred forests also play an important role in protecting habitats. Preserve the natural environment and is an important habitat for many animals and species. They also contribute to water conservation by protecting streams, rivers, and other water sources that flow through these areas.

In addition to its ecological importance Sacred forests also act as important carbon sinks. Capture carbon dioxide from the environment and mitigate the effects of climate change. It shows the interaction between environmental protection and human health.

Read also

  1. Reproduction in Organisms class 12
  2. Sexual Reproduction in Flowering Plants Class 12
  3. Human Reproduction Class 12
  4. Reproductive Health class 12
  5. Principles of Inheritance and Variation Class 12

Leave a Comment