CBSE Class 12 Biology Revision Notes Chapter 15

Class 12 Biology Chapter 15 Notes

Class 12 Biology, Chapter 15, explains Biodiversity and Conservation. The diversity of plant and animal life on earth is called biodiversity. Visit Extramarks to learn more about Biodiversity, its types, and Biodiversity and conservation notes. Sociobiologist Edward Wilson is credited with popularising the term “Biodiversity.”

The collection of Chapter 15 Biology Class 12 Notes complies with the current CBSE specifications because it thoroughly explains all of the topics and covers them all. Students can use the Class 12 Biology Chapter 15 Notes to study, analyse, and lessen their exam load. The academic experts at Extramarks used information from the NCERT textbook and other important sources to create these notes.

Students may register on Extramarks to access the Class 12 Biology Notes Chapter 15 and CBSE Class 12 Syllabus. Along with the Syllabus, students may also refer to CBSE Revision Notes, CBSE Sample Papers, CBSE Important Questions, CBSE Extra Questions, and CBSE past years’ question papers.

Key Topics Covered In Class 12 Biology Chapter 15 Notes

Following are the topics included in Biology Chapter 15 Class 12 Notes:

  • Biodiversity 
  • Biodiversity Conservation


Biodiversity is the combination of two words, biological and diversity. It was coined in 1985 by W.G.Rosen. The concept first appeared in the year 1980. “Bios” means life, and “diversity” means forms. It is a concept that varies from place to place.

Biodiversity is defined as the vast array of species of algae, microbes, fungi, plants, and animals that are present on the earth, either in terrestrial or aquatic habitats, and the ecological complexes of which they are a part.

There are three levels of biodiversity. There is genetic, species, community, and ecosystem diversity.

Genetic diversity:

A vast amount of genetic information is stored in  every living organism. Approximately 100 genes are present in a bacteriophage, 450-700 genes are present in mycoplasma, 13000 genes are present in Drosophila melanogaster, Oryza sativa has 32000 to 50000 genes and 31000 genes in Homo sapiens sapiens.

Genetic diversity is associated with the variation of genes within the species and these variations may be seen in alleles, entire genes, or chromosome structure. The morphological variations at all levels of species are distinct. There are a variety of intraspecific categories, like subspecies, races, strains, morphotypes, ecotypes, etc. This can be related to examples like there being many varieties of rice, mangoes, wheat, etc.

In imparting diversity to living organisms, the environment plays an important role. Genotype is altered by mutations. The genotypes that are best suited to the prevailing environment are selected by natural selection. As a result of this, polymorphs are formed, which basically means that individuals of the same species look different in the spatially contiguous populations, races in the distantly placed populations, and subspecies in the geographically isolated populations.

The raw material for adaptation to the changing environment and for the evolution of a new life is genetic diversity. An organism with genetic diversity has more sustenance against environmental perturbations. Crop plants with genetically uniform populations are more susceptibleto diseases.

In order to maintain diversity at both the species level and the community level, speciation plays an important role. When the environment diversifies and the number of species in the community increases, so does genetic diversity.

 Species diversity:

This diversity is measured at the level of species and it is completely associated with the numerical variety and richness of the species. Panthera tigris, Panthera leo and Panthera uncia come from the same genus but when compared to the species level, they are all different. Such examples can be also seen in Solanum melongena, Solanum tuberosum and Solanum lycopersicon.

Species richness refers to the number of species per unit area. The area of the site increases the number of species primarily due to the increased availability of natural resources. There may be differences in evenness and equitability.

Species evenness: 

This refers to the relative abundance with which each species is represented in an area.

It can be said that the product of species richness and species evenness gives species diversity. The diversity increases with variation in the species number, species types, and number of individuals per species.

Community and ecosystem diversity:

This type of diversity is related to the different types of ecosystems: 

  • Terrestrial habitat includes forests, grasslands, deserts, etc.
  • Aquatic habitat includes freshwater and marine 

Freshwater ecosystem contains:

  1. lentic: ponds and lakes
  2. lotic: streams, rivers
  3. wetlands: marshes, swamps, bogs

             marine ecosystem contains:

  1. open oceans
  2. upwelling regions
  3. coastal ecosystem includes:
  • estuaries
  • coral reefs
  • mangroves

the diversity in a number of niches, tropic levels, and processes of ecology that sustain the flow of energy, food webs, and recycling of nutrients. The number of ecosystems present in a habitat is called a measure of biodiversity.

Alpha diversity refers to the diversity within the community. It refers to the organism’s diversity, which means the number of species in the given habitat or community. The two indices that are used to present alpha diversity are species diversity and species evenness.

In a community, the distribution of species is uneven. This is determined by five factors. They are:

  • The historical factor which depicts the time that has been available for colonisation.
  • Number of potential colonisers which means the size of the species pool from which colonisation can occur.
  • The distance of the community from the source of colonisers.
  • There is an interaction between the species that is related to the extinction of some species and the survival of other species. 

Beta diversity refers to the diversity in the community. This is the rate of replacement of species along a gradient of habitats or communities within a given geographical location. If there is more dissimilarity between communities, then there will be more beta diversity.

Gamma diversity refers to the diversity of the habitats in the whole geographical region.

How many species are there on earth and how many in India?

As per IUCN facts and figures, the total number of plant and animal species described so far is slightly more than 1.5 million.

Animal species account for 70% of the total, with plant species accounting for no more than 22%.

 Insects are the most species-rich and they make up-to 70 % of the total. 

India is a mega-diversity nation. This is explained by many facts and figures.

India has attained a very unique distinction, and it has been assigned the status of a mega-diversity nation. It has very valuable gene pools upon which the foundation of modern agriculture, horticulture, silviculture, pisciculture, poultry, piggery, dairy, etc., is built. The country is rich in biogeographical regions, national parks, wildlife sanctuaries, biosphere reserves, wetlands, and world heritage sites. The country is rich in endemic flora and fauna. India has 2.4 % of the world’s land area.  It is one of the world’s 12 mega-diversity countries. India has nearly 45,000 plant species and twice as many animal species.1,00,000 plant species and 3,00,000 animal species are yet to be discovered and described.

Patterns of Biodiversity:

Latitudinal gradients:

  • The distribution of plants and animals throughout the world is not uniform. There is a progressive increase in biodiversity when one moves from the poles towards the equator. At the poles, the biodiversity is minimal. 
  •  Biodiversity is highest in tropical rainforests.
  • Colombia is located near the equator and has 1400 species of birds, while New York, at 41 degrees N, has only 105 species and Greenland, at 71 degrees N, has only 56 species.
  • The Amazon rainforest has the greatest biodiversity on earth with more than 40,000 plant species, 3000 fish species, 427 amphibian species, 378 reptile species, 1300 bird species, 427 mammal species, and 1,25,000 invertebrate species.
  • The hypothesis for the rich biodiversity in the tropics is
  • The tropical environment is older, so there is more time for the evolution of a larger number of both flora and fauna species.
  • Availability of more solar energy in the tropics. This leads to higher productivity and increased diversity.
  • The species have a low rate of extinction.
  • The environment is constant.
  • Enhancement of geographical isolation.
  • Reduced competition among the species.
  • The availability of resources is greater in the tropics, and only a few resources are used by each species.
  • Predation leads to limitation of the population size.

Species-area relationship:

Alexander von Humboldt, a German naturalist and geographer, observed that, up to a point, increasing explored area increases species richness within a region.

A rectangular hyperbola represents the relationship between species richness and area.

 The relationship shows a straight line on a logarithmic scale described in the equation as

Log S = log C + z log A

S = species richness

A = area

Z = slope of the line or the regression coefficient 

C = Y-intercept

The value of z lies in the range of 0.1 to 0.2

The slope would be 1.15 for fruit eating birds and mammals.

The value of z would range from 0.6 to 1.2 which is steeper when the analysis of the species-area relationship is done among very large areas like the continents.

There is a change in biodiversity with a change in altitude. When one moves from a higher altitude to a lower altitude, it basically increases. 

At higher altitudes, the biodiversity is lower. This is because of two factors, namely:

  • Decrease in temperature
  • Greater seasonal variability


Food  Carbohydrate-rich food
Fat and oil Soyabean, coconut, cottonseed, seasamum, sunflower, peanut, mustard, rapeseed, oil palm
Fibres  Cotton, flax, jute, hemp, rosella, agave, abaca and coir.
Drugs and medicines Vinca rosea, Papaver somniferum, Cinchona, Taxus brevifolia and Rauwolfia serpentina.
Esthetic  Ecotourism, birdwatching, wildlife pet keeping.
Cultural benefits Ocimum sanctum(Tulsi), Ficus religiosa, Prosopis cineraria, sacred birds and snakes
Ecosystem services Climate and gaseous temperature is controlled by forest and oceans, nutrient cycling, conservation of water and conservation of soil.
New varieties

Obtained from crossing with wild varieties

Disease-free rice plants are obtained by crossing rice plants with Oryza nivara (wild). Potatoes resistant to late blight, potato mosaic virus, leaf roll virus, and nematodes are also obtained.

The Benefits of Biodiversity are as under:

  • Source of food and improved varieties:

There are many species of plants and animals which are edible. Wheat, maize and rice are the three carbohydrate-rich crops that yield nearly two-thirds of the world’s food production. The population is increasing, and in order to meet the increasing food requirements, man is exploring both plant varieties and animal food sources.

The source material for breeding improved varieties is biodiversity.

In an attempt to improve the desired traits, the commercial or domesticated species crossbreed with their wild relatives. This led to the development of disease-resistant and high-yielding varieties of crops. For example, cross-breeding of Oryza nivara, which is wild rice, has developed rice varieties that are resistant to the four main rice diseases. Through cross-breeding experiments, potatoes have been made resistant to late blight disease, potato mosaic virus, five races of cyst nematodes, etc.

In order to increase the yield of milk, meat and eggs the hybrid animal varieties are produced.

New varieties must be produced constantly in order to meet the changing requirements. Wild varieties serve as gene banks, providing genes in order to produce high-yielding, disease-resistant varieties. Sugarcane is genetically modified to be resistant to red rot.

  • Fibres: Cotton, hemp, jute, sunn hemp, Agave, and Abaca are some of the common sources of fibres. More varieties of plants are being explored to obtain superior fibres.
  • Biodiversity as a source of useful products:

The various plant species provide us with a range of useful materials like gum, resins, dyes, fragrances, tea, coffee, dry fruits, etc. similar animals also provide us with waxes, lubricants  honey, silk, waxes, pearls, ivory, horns, antlers, skin, leather, fur, etc.

  • Drugs and medicines: Medicines are therapeutic products and are obtained from a variety of plant species. For example, Quinine which is obtained from the bark of the Cinchona tree is useful to combat malaria. Taxol obtained from the tree Taxus brevifolia, Taxus baccata are used to treat cancer. Morphine for treating pain is obtained from Papaver somniferum. Schizophrenia and blood pressure are treated with resperine, which is obtained from Rauwolfia serpentina. Plant products are useful in providing many health benefits.
  • Sports and recreation: the visits to the garden, wildlife sanctuaries, fishing etc., are very pleasing.
  • Scientific value: The animals are used in scientific research. Some of the animals commonly used are rats, pigs, monkeys, etc., and new surgical techniques are applied to animals. Animals add a lot of value to biological and medical research.
  • Aesthetic value: Green forests, flowers, birds, fishes, butterflies, etc., are the beauty of biodiversity.
  • Cultural value: Wildlife represents the cultural asset of the country. The ancient scripture depicts plants and animals.
  • Ethical requirements:  The living organisms that exist today are the result of evolution, which took nearly 3.5 billion years. Once a species is lost, it is lost forever, so we must aim to save species from extinction.
  • Right to live: Man has the right to live, and similarly, animals also have the right to live. Every species must have an equal chance to survive.
  • Ecosystem services: Biodiversity is responsible for maintaining ecological services. Oxygen is obtained by the process of photosynthesis. Some other related examples are pollination by bees and birds, regulation of the global climate, control of floods and soil erosion, nutrient cycling, microbial waste treatment, biological control of pests, etc.
  • Ecological balance: All organisms in the food chain interact in such a way that the natural cycle keeps going. If any of the links of the food chain disappear, then it upsets nature’s balance and creates problems.



  • IUCN stands for the International Union for the Conservation of Nature and Natural Resources. It is now called the World Conservation Union (WCU) and it maintains a document called a “red list” or “red data book” of taxa that are facing the risk of extinction. The basic objective of the “red list” category is to: Increase awareness about how important threatened biodiversity is.
  • A global index of the already-existing biodiversity decline is provided.
  • Endangered species are identified and documented.
  • For guiding the action of conversation.
  • To highlight and prioritise conservation.
  • Information is provided on international agreements.


The IUCN red list was initiated in 1963. There are 8 categories in the red list species category. They are extinct, extinct in the wild, critically endangered, endangered, vulnerable, lower risk, data deficient and not evaluated.

The species that are facing extinction are vulnerable, endangered, and critically endangered.

Some of the large body size species susceptible to extinction are the Bengal tiger, lion, and elephant.

Species with a low population size and a low reproductive rate are also susceptible to extinction. They are blue whales and giant pandas.

The number of species described for all organisms on Earth ranges between 1.7 million and 1.8 million. This is 15 % of the total number. 

According to the Wildlife Institute of India, there are ten biogeographical regions. They are:

  • The Trans Himalayas are a cold desert with sparse vegetation. Besides the snow leopard, it has a rich community of goats and wild sheep.
  • Desert
  • Semi-arid
  • Western ghats account for 4 % of the geographical area. They are wild relatives of many cultivated plants. These also have a large number of endemic amphibian species.
  • The Deccan Peninsula has the most extensive coverage among the biogeographical regions and accounts for 42 % of the Indian mass.
  • Gangetic plain
  • Northeast accounts for 5.2 % of the geographical area. They have wild relatives of mango, banana, citrus, pepper, etc.
  • coasts
  • Islands 


When the last member of a species dies and it disappears from the earth, it is known as extinction. 

The role of humans in extinction is that, In the biosphere, the most powerful species is man, and he is responsible for the extinction of many species due to overexploitation. When a species becomes extinct, then its gene pool is also erased forever.

There are basically three types of extinction. They are:

  • Natural extinction: This refers to the slow replacement of a species with a better-adapted species, which is the result of changes in the conditions of the environment. This is also known as “background extinction.”
  • Another type of extinction is mass extinction, which occurs when a large number of species become extinct as a result of natural disasters.In the earth’s geological history, this has occurred several times. In the Permian period of the geological time scale, nearly 90 per cent of the shallow-water marine invertebrates went extinct. As a result of the big collision of a big meteorite with the earth, it is said that dinosaurs went extinct. This disappearance is an example of mass extinction.
  • Anthropogenic extinction: The disappearance of species as a result of human activity.According to the reports of World Conservation Monitoring, 533 animal species and 384 plant species became extinct as a result of human activities.

There are certain population traits that make a species susceptible to extinction. They are

  • Large body sizes of animals like elephants, rhinoceroses, Bengal tigers, lions, etc.
  • Small population size
  • Blue whales and giant pandas, for example, have a low rate of reproduction or a low potential for reproduction.
  • High status at trophic levels like the bald eagle and Bengal tiger.
  • For example, woodland caribou have a narrow range distribution or a small geographical range.
  • Inability to switch over to alternate foods

Some of the Factors contributing to extinction, as explained by Class 12 Biology Chapter 15 Notes are:

  • Hunting: Wild animals are hunted by animals for food, safety, trade, and fun. This is referred to as subsistence hunting, commercial hunting, and sports hunting, in that order.

The trade of animal products includes hides, furs, leathers, feathers, horns, ivory, meat, etc. There are many species of birds and animals which are on the verge of extinction due to human activities. Mollusks, fish, sea turtles, birds, sea cows, and whales are facing extinction. This also shows that man is no longer in a co-evolved balance with the environment.

Overfishing for food is depleting marine and freshwater living resources.

  • Forest fires: in the past, forest fires have been related to the large-scale elimination of many species. 
  • Destruction of habitats and fermentation: The natural habitats of animal species are destroyed due to the following reasons:
  1. Developmental work: The natural habitat of wildlife is greatly reduced due to human activities like settlements, harbours, industries, mines, croplands, pastures, etc. The movement of wildlife is limited due to the passage of railway lines through the forests. The animals are scared of the sound produced by the passing vehicles.
  2. Deforestation: The wildlife is deprived of cover and food due to deforestation. The free movement of the animals and their reproductive capacity is reduced due to deforestation. Some of examples are rhinoceros, bison, tiger, etc.
  3. Pollution: This has resulted in reduced life expectancy and degradation of habitats
  4. Cleanliness: Human cleanliness destroys animals. The California condor or vulture is the largest flying bird and is suffering due to human cleanliness. 
  5. Fragmentation of habitat: The example is a forest patch surrounded by croplands. In such cases, the species that occupy the deeper part of the forest will be affected most, becoming vulnerable and ultimately becoming extinct. 

Alien species invasion or Introduction of exotic species: 

Native species are adversely affected by the introduction of exotic species by man. This led to increased competition for food and space between the exotic and native species. This may also result in habitat degradation, disease transmission, and parasite introduction.The examples include, introduction of Clarias gariepinusinto rivers, which led to the total loss of Clarias batrachus, which is the local species. Water hyacinth also threatens the existing aquatic species in ponds and lakes.


Some animals leave the habitat, while others die there. When the habitat breaks into small patches as a result of developmental activities like agriculture, water bodies, and other reasons, it causes habitat fragmentation. This causes a reduction in the core area and an increase in the edge area. Species inhabiting the deep or interior portion of the forest suffer as a result of the disruption of their inter-relationships.The habitats of the species shrink as a result of fragmentation, so this also leads to the disappearance of the rare species.

  • Some of the examples of fragmented habitats are forest patches with croplands, orchards, plantations, and urban settlements.
  • Fragmentation of habitat, like, for example, forest land surrounded by croplands, orchards, plantations, and urban areas, leads to the disruption of species in the cleared region and the annihilation of species restricted to deeper, undisturbed parts of the forest, resulting in decreased biodiversity in the habitat fragments.
  • When species diversity reduces in small patches, it is called insularisation. Initially,  there is usually an increase in the number of the species in patches, but ultimately it decreases.


  • Industrial pollution like industrial emissions and effluents, automobile emissions, pesticides, fertilisers, sewage are responsible for making harmful alterations in the surrounding environment. Population load and pollution load have proven harmful to the ecological system. Acid rain, caused by excessive sulphur and nitrogen oxide emissions, destroyed nearly half of the natural forests as well as freshwater lakes.
  • Oil spills also cause significant harm to plankton, algae, marine animals, and sea birds.This has caused their immobility and death. 
  • Sulphur dioxide pollution causes damage to the lichen population in the area.
  • Pesticides used in agricultural practises enter the food chain and cause biomagnification.
  • Lead and other heavy metals enter the bodies of water and cause mortality in animals as this water is used by animals for drinking.


The water bodies get enriched due to the runoff from the fields and sewage disposal. This nutrient enrichment causes a dense growth of the plants, and it also blocks the oxygen supply as it leads to the depletion of oxygen. There is organic matter accumulation and fouling of the water.


  • The human population is increasing the pressure due to which agriculture has become both extensive and intensive.
  • Extension of agriculture is related to the diminishing of wetlands, grasslands, and forests.
  • Intensive agriculture is related to a few crops and their few high-yielding varieties, and as a result of this, there is a reduction in genetic diversity. The other varieties which are remaining are disappearing fast. Similarly, the crops with smaller yields and returns are being edged out of cultivation, and this has also decreased the biodiversity.
  • The huge spread of agriculture at the cost of grasslands, forests, and habitat destructionhas led to theextinction of species.


There are two types of biodiversity conservation methods: in situ conservation and ex situ conservation.Extramarks Class 12 Biology Chapter 15 Notes explains the two in detail in the section that follows.


This method of conservation is the most appropriate method to maintain the species of wild animals and plants in their natural habitats.

In this way, a total ecosystem is preserved through a network of protected areas.

The natural habitat for in situ conservation are:

  • National parks
  • Wildlife sanctuaries
  • Biosphere reserves
  • Wetlands
  • Mangroves
  • Coral reefs
  • Sacred groves and lakes.

In situ conservation also includes the introduction of species of plants and animals back into various practices like agricultural, horticulture, animal husbandry so that they are cultivated and reproduced for  reuse by the farmers and other people.

The tubers, rhizomes, bulbs, and seeds of a large variety of species of plants are restored by the farmers so that they are cultivated for the next season.

Animal husbandry professionals care for species that are resistant to diseases, drought, and other adversities.

A sanctuary is an area dedicated solely to animal conservation.Only certain activities are allowed that do not affect the animals, like procuring timber, minor forest products, and private ownership rights.

The concept of a biosphere reserve was evolved by UNESCO’s Man and Biosphere Programme (MABP). This is a reserved area in which multiple uses of land are permitted by dividing it into zones, each for a particular activity. A biosphere reserve is divided into three zones: Core, buffer and manipulation zone.

In the core zone, no human activity is allowed, in the buffer zone, limited human activity is allowed and in the manipulation zone, several human activities are allowed. 

The role of the biosphere reserve is very important as it preserves the following:

  • Wild populations
  • Lifestyle of tribals
  • Genetic resources of domesticated plants and animals.

In 1986, the Nilgiri Biosphere reserve was planned in India.

Some of the popular national parks and sanctuaries in India are highlighted here by Extramarks Class 12 Biology Chapter 15 Notes:

  • Corbett National Park
  • Kanha National Park
  • Kaziranga National Park
  • Gir National Park
  • Bandipur National Park
  • Jaldapara Sanctuary
  • Bir Moti Bagh Sanctuary
  • Sultanpur Lake Bird Sanctuary
  • Shikari Devi Sanctuary
  • Dachigam Sanctuary
  • Hazaribagh National Park
  • Periyar Sanctuary
  • Desert National Park
  • Simlipal
  • Nagarjunasagar Sanctuary
  • Annamalai


Due to the direct e or indirect interference of human activities, those regions of rich biodiversity thathave been declared sensitive are called hot spots. The concept of hot spots was first developed in  1988 by Norman Myers in order to designate priority areas for in situ conservation. The two main areas for determining the hot spots are:

  • The total number of the endemic species
  • The loss of habitat is analogous to a level of threat.

There are a total of twenty “hot spots” identified worldwide.

In India, there are two hotspots: the Western Ghats and the Eastern Himalayas. These areas are representative of a high degree of endemism and are rich in flowering plants, reptiles, amphibians, swallow-tailed butterflies, and a few varieties of mammals.

The Western Ghats occur along the western coast of India and extend for about 1600 km through Maharashtra, Karnataka, Tamil Nadu and Kerala to Sri Lanka. These areas have good rainfall.

Evergreen forests can be found at low elevations of up to 500 meters.

The forests that lie on the moderate level of 500 to 1500 m are semi evergreen.

Nearly 1600 species of plants are endemic to this area.

Malabar is the other name for Southern Western Ghats

The region has high biodiversity along with a high degree of threat perception to biodiversity.

There are three threatened areas recognised by the IUCN: the Agastyamalai Hills, Silent Valley, and Periyar National Park which is the New Amambulam Reserve.

Indian, Malayan, and Chinese are the three biogeographical regions that meet at the Eastern Himalayas. This is extended to Bhutan and then north-east to Myanmar and is called the Indo-Burma hotspot.

Class 12 Biology Chapter 15 Notes highlight the threats to India’s biodiversity hotspots.

  • Tourist interference and invasion
  • Mining activities
  • Exploitation of fish, aquatic life and ship farming
  • Population pressure and alteration of habitat
  • Loss of wildlife
  • Drying of lake
  • Hunting activities
  • Dumping of sewage
  • Construction of dam
  • Siltation
  • Tea and coffee plantation
  • Urbanisation 
  • Erosion of coastal habitats
  • Desertification
  • Developmental activities

Sacred grooves 

This refers to the sacred forest patches around the places of worship. They are held in high esteem by tribal communication or the central government. These are the undisturbed patches of forest that are usually surrounded by  degraded landscapes. The sacred grooves in India are found in several states like Meghalaya, Madhya Pradesh, Karnataka, Kerala, etc. In these sacred grooves, the tribals are not allowed to even cut a single branch of a tree. This is the reason why  endemic species or  rare species flourish in the sacred grooves. Many tribes, like for example Bishnois of Rajasthan protect Prosopis cinerariaand black buck religiously. Some water bodies are also held sacred in sacred groves.The flora and fauna are naturally preserved in such areas.


Human interference is increasing, so for rare species, in situ conservation may not be a viable option. Species may decline or become extinct due to various factors like genetic drift and interbreeding, habitat loss,variations in demography and environment, competition with  exotic species, diseases, and overexploitation. So under these circumstances, the most viable option is ex situ conservation. In this, under human supervision, the individual species are maintained in artificial conditions. There are various approaches involved in ex situ conservation, Class 12 Biology Chapter 15 Notes highlights the following:

  • Rare plants are cultivated in this approach.
  • The threatened animal species are reared in the Botanical garden and the zoological gardens
  • Preservation of seeds in the seed banks.
  • Adaptation of tissue culture techniques.
  • Conservation of gene banks and pollens from various species


It is a very useful technique and is related to in-vitro conservation. This technique can preserve vegetatively propagated crops, for example, seeds of plants, potatoes, preserving eggs, sperms and cells. The embryonic tissues of the animals are preserved at -196 degree celcius. By using similar techniques, endangered animal species can also be preserved.

A frozen zoo has been established by the Zoological Society of San Diego to store more than 355 species of different animals including reptiles, birds and mammals. Nearly 1500 botanical gardens and 80,000 species in arboreta are present. Nearly 800 zoos are professionally managed with 3000 vertebrate species of amphibians, birds, mammals and reptiles. There are well developed captive breeding programmes in these zoos. 

In India, for the conservation of plant and animal resources, the National Bureau of Plant Genetic Resources of New Delhi and The National Bureau of the Animal Genetic Resources, Karnal are engaged in the conservation of plant and animal resources.

Class 12 Biology Chapter 15 Notes: Exercises & Solutions

By using the educational study resources that Extramarks provides, students in Class 12 can quickly understand each Chapter of the complete Biology Syllabus. Biology will be easy to learn once students have access to the most updated syllabus, chapter notes, question-and-answer solutions, etc. Students who sign up for Extramarks can access the Class 12 Biology Chapter 15 Notes anytime and from any location.

The Class 12 Biology Chapter 15 Notes on Biodiversity and Conservation were written using straightforward explanations. Based on the CBSE Syllabus, students may find the Notes to be of great use. Students can access the exercises and solutions for certain chapters by following the links below.

  • Chapter 15: Exercise 15.1 Solutions
  • Chapter 15: Exercise 15.2 Solutions 
  • Chapter 15: Exercise 15.3 Solutions
  • Chapter 15: Exercise 15.4 Solutions
  • Chapter 15: Exercise 15.5 Solutions
  • Chapter 15: Exercise 15.6 Solutions
  • Chapter 15: Exercise 15.7 Solutions
  • Chapter 15: Exercise 15.8 Solutions
  • Chapter 15: Exercise 15.9 Solutions
  • Chapter 15: Exercise 15.10 Solutions

For Class 12 Biology Chapter 15, Extramarks has fantastic study materials that are thorough and accurate. These study materials aid students in comprehending the main Chapters’ content and deciphering their questions. These study tools are intended to aid students in understanding the Chapters in the CBSE Class 12 textbooks, enabling them to perform well on their Class 12 exams.

Students get access to additional sources of instructional content for various classes on the Extramarks website. Click on the appropriate links below to learn more.

  • NCERT Solutions
  • CBSE Syllabus
  • Important Formulas
  • CBSE Extra Questions
  • CBSE Revision Notes
  • CBSE Notes
  • Important Questions
  • CBSE Past Year Question Papers
  • CBSE Sample Papers

NCERT Exemplar Class 12 Biology

Biology calls for constant studies and research. Students are urged to attempt a significant number of questions due to the length of the class 12 Biology course.

Students can use the NCERT Exemplar for Class 12 Biology to create questions and solutions from past exam papers. The Exemplar has a variety of question categories, including multiple-choice, lengthy answers, and short answers.

Our study materials for Class 12 Biology Chapter 15 Notes now include in-depth, prepared Extramarks explanations for the answers. The solutions to the exemplar problems aid students in developing critical thinking skills and problem-solving techniques. Working through these assignments will help students better understand the various topics covered in Chapter 15. In addition to the sample solutions, our Class 12 Biology Chapter 15 notes and study materials include CBSE revision notes, questions from the previous year’s exams, and other study tools. 

Key Features of Class 12 Biology Chapter 15 Notes

The main features of Class 12 Biology Chapter 15 Notes provided by Extramarks are listed below:

  • It provides clear information that is easily accessible.
  • It enhances time management skills.
  • It provides a thorough but understandable explanation of each subject.
  • The CBSE curriculum is utilised.
  • The Extramarks faculty members who wrote these remarks all have graduate degrees.
  • It makes each topic understandable.
  • It places a focus on writing concise, in-depth Notes.

To access all of the study materials for the Class 12 Biology Chapter 15 Notes, we urge students to register on the Extramarks website.

FAQs (Frequently Asked Questions)

1. According to Class 12 Biology's Chapter 15, what sorts of Biodiversities exist?

Genetic Biodiversity, Species Biodiversity, and Ecological Biodiversity are the three basic categories under which Biodiversity is divided. The distinction between people based on their DNA is called Genetic Biodiversity. Species biodiversity distinguishes each community of species based on its characteristics.At the same time, Ecological Biodiversity refers to all the diversity in a specific region’s ecosystem. Extramarks Class 12 Biology Chapter 15 Notes provides greater information on Biodiversity and its various forms.

2. How can I prepare for Biology Chapter 15 in Class 12?

Students can acquire the NCERT solutions and study materials for the Class 12 Biology chapter on Biodiversity at Extramarks. The extensive course outline might be too much for the students. As a result, topic specialists created solutions and notes to help students with their board preparation. With the use of chapter notes covering all the key points, revision before the exam is also facilitated—the Extramarks-provided solutions and annotations.

3. In accordance with Chapter 15 of Biology for Class 12, how is Biodiversity threatened?

Urbanisation and increased Industrialisation are both results of the expanding population. As a result, more stray animals and trees and plants are destroyed. The threat to biodiversity is increasing. As consumer demand for goods generated from varied diversity has grown, the ecosystem has become unbalanced. Because each type of diversity has its own value, it may be dangerous if we do not take the right steps to preserve it.

4. What justifies the Conservation of Biodiversity, as stated in Biology Class 12 Chapter 15?

Extramarks Class 12 Biology Chapter 15 Notes present the following reasons that support the need for biodiversity conservation:

  • Plants and animals meet numerous fundamental and practical human requirements.
  • They ought to be kept for our coming generation.
  • Our only source of oxygen plants.
  • Animals and birds are necessary for pollination.

Numerous plants provide benefits to humans, including food, building materials, fibre, and even components for medicines. The conservation of plants and animals is crucial not only for their uses but also for generating cash.

5. What does Chapter 15 of Biology for Class 12 define as Biodiversity Conservation?

The variety of plants and animals on the earth is known as Biodiversity. The protection, enhancement, and management of biodiversity, or the variety of plants and animals, is referred to as Biodiversity Conservation. There are two ways to accomplish this as per Extramarks Class 12 Biology Chapter 15 Notes:

  • In-situ Conservation: Sanctuaries, national parks, biosphere reserves, and so on are examples of in-situ biodiversity conservation where plants and animals are preserved within their natural habitat.
  • Ex-situ conservation: zoological parks, botanical gardens, and other places where endangered flora and fauna are kept in order to count them.