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[Updated] CBSE Class 12 Biology Biodiversity and Conservation Notes 2024-25 in PDF

Get a comprehensive understanding of biodiversity and conservation with CBSE Class 12 Biology Biodiversity and Conservation Notes. These notes delve into the intricate concepts outlined in the CBSE syllabus, offering clear explanations and detailed insights. With these notes, students can grasp the nuances of biodiversity, its significance, threats, and conservation measures. Perfect for exam preparation, these notes provide a concise yet comprehensive resource for scoring well in the CBSE Class 12 Biology exam.

Before discussing the Class 12 Biology Biodiversity and Conservation Notes, let us check the CBSE Class 12 Summary; below, we have mentioned the complete CBSE Class 12 Summary.

Class 12 Biology Biodiversity and Conservation Notes

Below, we have mentioned the CBSE Class 12 Biology Biodiversity and Conservation Notes. Students have checked the complete Class 12 Biology Biodiversity and Conservation Notes PDF for the final examination’s excellent score.

Class 12 Biodiversity and Conservation Marking Scheme

Students trying to make a career in the medical field, like pharmacy, dental, BAMS, MBBS, etc., must remember that they have to score excellent marks in their CBSE class 12 board examination. The marking scheme is the proper distribution of marks according to the Units or Chapters. In addition, it will show students the importance of Class 12 Biodiversity and Conservation and the total number of questions asked from this chapter.

NOTE:- To know more information about the Class 12 Biology Marking Scheme

Class 12 Biology Syllabus 2024-25

Biology is the study of life and living organisms. The primary way of introducing biology in the school curriculum is to help students learn more about the human body parts, names, functions, importance, and many more. As you all know, the CBSE has already released the Class 12 Biology Syllabus for the 2024-25 academic year; we have the syllabus in PDF format. Let’s have a look.

Class 12 Biology Exam Pattern

In this section, we have mentioned the Class 12 Biology Exam Pattern. Students can check the Class 12 Biology Exam Pattern for the academic year 2024.

NOTE:- To learn more About the Class 12 New Biology Syllabus Session 2024-25

Class 12 Biology Sample Paper

Class 12 Biology Sample Papers for the board exam 2024-25 have been released by the Central Board of Secondary Education (CBSE). Students must Download the complete Class 12 Biology Sample Papers in PDF for the final examination’s excellent score. Also, the marking scheme and answer key for each paper is available. In addition, you can download the Last 6th Year Sample Paper 2023, 2022, 2021, 2020, 2019, 2018, 2017, 2016, and 2015.

NOTE:- To know more information about the Class 12 Biology Sample Paper

Class 12 Biology Useful Resources

We have tried to bring CBSE Class 12 Biology NCERT Study Materials like Syllabus, Worksheet, Sample Paper, NCERT Solutions, Important Books, Holiday Homework, Previous Year Question Papers, etc. You can visit all these important topics by clicking the links given.​

Frequently Asked Questions (FAQ)

Q. how many types of biodiversity conservation are .

A. There are three prime biodiversity types: Genetic, Species, and habitat/ecosystem.

Q. What is biodiversity conservation and its importance?

A. Biodiversity conservation, the practice of protecting and preserving the wealth and variety of species, habitats, ecosystems, and genetic diversity on the planet, is essential for our health, wealth, food, fuel, and services we depend on. … Biodiversity conservation is vital for economic growth and poverty reduction.

Q. Is class 12 biology difficult?

Per the feedback of the students who appeared for the Biology paper today, the difficulty level of the CBSE Class 12 Biology exam 2023 was average. Students shared that the questions were from the syllabus, and the paper was easy.

Q. Which is not a benefit of biodiversity?

A. Explanation: Deforestation is a common issue that lessens the number of trees, affecting lives and negatively affecting an enormous variety of life on Earth.

Q. Is Edufever study material free?

A. CBSE Study Materials – Access All Resources for Free!

Q. Does Edufever provide study material?

A. We at Edufever provide CBSE boards with Study Materials to assist you in preparing for your upcoming exam. Studying this helps you understand the exam pattern set by the CBSE board’s study material this year.

Q. Should I make Biology notes?

A. You must write your notes keeping in mind the essential concepts of the syllabus that could be asked in the exam. So don’t keep on writing whatever you are learning. Instead, write short notes that make sense.

Q. Are there any changes in the CBSE Class 12 Biology Syllabus for 2024-25?

A. According to the latest updates, there is no update on decreasing the CBSE 12 Biology Syllabus for the academic year 2024-25.

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Biodiversity and Conservation class 12 Notes Biology

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Class 12 Biology notes Chapter 15 Biodiversity and Conservation

Download CBSE class 12th revision notes for chapter 15 Biodiversity and Conservation in PDF format for free. Download revision notes for Biodiversity and Conservation class 12 Notes and score high in exams. These are the Biodiversity and Conservation class 12 Notes prepared by team of expert teachers. The revision notes help you revise the whole chapter 15 in minutes. Revision notes in exam days is one of the best tips recommended by teachers during exam days.

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CBSE Class 12 Biology Revision Notes Chapter 15 Biodiversity and Conservation

Biodiversity or biological diversity is the occurrence of different types of ecosystems, different species of organisms and their variant like biotypes, ecotypes and gene adapted to different climates and environments of different regions including their interactions and processes.This term was coined by Edward Wilson.The vast array of species of micro-organisms, algae, fungi, plants and animals occurring on the earth either in the terrestrial or aquatic habitats and the ecological complexes of which they are a part comprises biodiversity . Diversity ranges from macromolecules to biomes.

The important diversity at the levels of biological organization are-

I. Genetic Diversity- a single species might show high diversity at the genetic level over its distributional range.  Rauwolfia vomitoria  shows genetic variation in terms of concentration and potency of chemical reserpine India has more than 50,000 genetically different strains of rice and 1000 varieties of mango.

II. Species Diversity- diversity at species level for example, the Western Ghats have more amphibian species diversity than the Eastern Ghats.

III. Ecological Diversity- deserts, rain forests, mangroves, coral reefs, wetlands, estuaries and alpine meadows are types of ecological diversity.

Biodiversity and its conservation are vital environmental issues of international concern as more and more people around the world begin to realize the critical importance of biodiversity for survival and well-being on this planet.

· According to the IUCN, the total number of plant and animal species described so far is about 1.5 million but still many species are yet to discovered and described.

· More than 70% of all the species recorded are animals while rest are plants including algae, fungi, bryophytes, gymnosperms and angiosperms. Among animals, 70% of total are insects.

· The number of fungi species in the world is more than the combined total of the species of fishes, amphibians, reptiles and mammals.

BIODIVERSITY IN INDIA

• India is one of the twelve mega biodiversity countries of the world. • India has only 2.4% of the land area of the world, it has 8.1% of the global species biodiversity. • There are about 45,000 species of plants and about 90,000-1,00,000 species of animals. • New species are yet to be discovered and named. • Applying Robert May’s global estimate, only 22% of the total species have been recorded, India has probably more than 1,00,000 species of plants and 3,00,000 species of animals to be discovered and described

Patterns of Biodiversity

a) Latitudinal gradients- the diversity of plants and animals is not uniform throughout the world and shows uneven distribution. This distribution pattern is along the latitudinal gradient in diversity. Species diversity decreases as we move away from the equator towards the poles. Tropics harbor more species than temperate or polar areas.Amazonian Rainforest has the greatest biodiversity on earth. It has more than 40000 species of plants, 1,25,000 species of insects, 300 species of fish, 427 of amphibian and 378 of reptiles, 1300 species of birds and 427 of mammals. Various hypothesis has been proposed regarding this such as-

a) Speciation is a function of time unlike temperate regions subjected to frequent glaciation in past, tropical latitudes have remained relatively undisturbed for millions of years and thus had long evolutionary time for species diversification.

b) Tropical environments unlike temperate ones are less seasonal and more constant and predictable which promote niche specialization and lead to a greater species diversity.

c)There is more solar energy available in the tropics which contribute to higher productivity  this in turn contribute indirectly to greater diversity.

b) Species-Area relationships

• Alexander Von Humboldt has observed that within a region, species richness gets increased when explored area is increased, but only up to a limit. • The relationship between species richness and area for a number of taxa like angiospermic plants, fresh water fishes and birds is found to be a rectangular hyperbola.

On logarithmic scale, the relationship is a straight line described by the equation-

log S = log C + Z log A.

Where, S= species, A= Area, Z= slope of the line, C =Y- intercept.

• Ecologists have discovered that the value of Z lies in range of 0.1 to 0.2 regardless of taxonomic group of the region.
•   In very large area like continents, Z value ranges between 0.6 & 1.2.

The importance of Species Diversity to the Ecosystem

The communities with more species are generally more stable than those with less species. A stable community should not be show too much variation in productivity from year to year.

Rich biodiversity is essential for ecosystem health and imperative for the very survival of human race on this planet.

Rivet popper hypothesis – given by   Paul Ehrlich. In an airplane (ecosystem) all parts are joined together using thousands of rivets (species). If every passenger travelling in it starts popping a rivet to take home (causing a species to become extinct), it may not affect flight safety (proper functioning of the ecosystem) initially, but as more and more rivets are removed, the plane becomes dangerously weak over a period of time. Furthermore, which rivet is removed may also be critical. Loss of rivets on the wings (key species that drive major ecosystem functions) is obviously a more serious threat to flight safety than loss of a few rivets on the seats or windows inside the plane

Loss of Biodiversity

The biological wealth of our planets have been declining rapidly due to three factors – Population, Urbanisation and Industrialisation.The IUCN Red List (2004) documents the extinction of 784 species (including 338 vertebrates, 359 invertebrates and 87 plants) in the last 500 years. Some examples of recent extinctions include the dodo (Mauritius), quagga (Africa), thylacine (Australia), Steller’s Sea Cow (Russia) and three subspecies (Bali, Javan, Caspian) of tiger. In last 20 years, 27 species have been disappeared. In general, loss of biodiversity in a region may lead to

a. Decline in plant production

b. Lowered resistance to environmental perturbations, drought, and flood.

c. Increased variability in ecosystem processes such as productivity, water use, and pest and disease cycles.

Causes of biodiversity losses

Faster rates of species extinctions are largely due to human activities. The four major causes are called ‘The Evil Quartet’.

1) Habitat loss and fragmentation – is the most important cause of animals and plants extinction. The amazon rain forest (lungs of the planet) having millions of species is being cut and cleared for cultivating soya beans or for conversion to grasslands. When large habitats are broken up into small fragments due to various human activities, mammals are birds requiring large territories migrate and badly affected.

2) Over-exploitation –    When biological system is over exploited by man for the natural resources ,it results in degradation and extinction of the resources ,  e.g Steller’s sea cow, passenger pigeon etc.  Many marine fish population are over harvested, endangering the continued existence of some important species.

3) Alien species invasions – when alien species enters intentionally or unintentionally, some of them turn invasive and cause decline or extinction of indigenous species.The Nile perch introduced into Lake Victoria in east Africa led eventually to the extinction of an ecologically unique assemblage of more than 200 species of cichlid fish in the lake. Invasive weeds species like carrot grass (parthenium), Lantana and water hyacinth causing threats to indigenous species.

4) Co-extinctions – when a species becomes extinct, the plant and animal species associated with it also become extinct. When a host fish species becomes extinct, its unique assemblage of parasites also becomes extinct.

Biodiversity Conservation

We should conserve the biodiversity due to following groups of regions-

I. The narrowly utilitarian – human obtain countless direct economic benefits from nature like food, firewood, fibres, construction material, medicinal plants and industrial products. With increasing resources put into ‘bio-prospecting’ nations endowed with rich biodiversity can expect to reap enormous benefits.

II. The Broadly Utilitarian – biodiversity plays a major role in ecosystem services that nature provides. Productions of Oxygen during photosynthesis, pollination without natural pollinator, pleasure from nature are priceless.

III. Ethical – for conserving biodiversity relates to what we own to millions of plants, animals and microbes species with whom we share this planet. Every species has an intrinsic value although it may not be of current or any economic value to us. It is our moral duty to care for their well-being and pass on our biological legacy in good order to future generations.

How do we conserve Biodiversity?

When whole ecosystem is conserved, all its biodiversity is also protected. There are two ways of conservation of biodiversity-

In situ ( on site) conservation – conservationists have identified for maximum protection certain ‘biodiversity hotspots’ regions with very high levels of species richness and high degree of endemism, species found in that region and not found anywhere else. There are 34 biodiversity hot spots in the world. These hotspots are also regions of accelerated habitat loss. India has 14 biosphere reserves, 90 national parks and 448 wildlife sanctuaries.

Ex situ (off site) conservation – in this method, threatened animals and plants are taken out from their natural habitat and placed in special setting when they be protected and given special care . Zoological parks, Botanical Gardens and wildlife safari parks are used for this purpose. Now gemetes of threatened species can be preserved in viable and fertile condition for long periods of time using cryopreservation technique. Eggs can be fertilized in vitro and plants can be propagated using tissue culture methods.

The historic convention on Biological Diversity (The Earth Summit) held in Rio de Janeiro in 1992,called upon all nations to take appropriate measures for conservation of biodiversity and the World Summit on  sustainable development held in 2002 in Johannesburg, South Africa, 190 countries pledged their commitment to achieve by 2010, a significant reduction in the current rate of biodiversity loss at global, regional and local levels.     

CBSE Class 12 Revision Notes and Key Points

Biodiversity and Conservation class 12 Notes Biology. CBSE quick revision note for class-12 Chemistry Physics Math’s, Biology and other subject are very helpful to revise the whole syllabus during exam days. The revision notes covers all important formulas and concepts given in the chapter. Even if you wish to have an overview of a chapter, quick revision notes are here to do if for you. These notes will certainly save your time during stressful exam days.

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there are 3000 species of fishes in amazonian rain forest not 300

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Biodiversity and Conservation Class 12 Biology Notes And Questions

Please refer to Biodiversity and Conservation Class 12 Biology notes and questions with solutions below. These revision notes and important examination questions have been prepared based on the latest Science books for Class 12. You can go through the questions and solutions below which will help you to get better marks in your examinations. We have provided the latest Class 12 Biology Notes and Questions for all chapters in your NCERT Class 12 Biology Book.

Class 12 Biology Biodiversity and Conservation Notes and Questions

Biodiversity is the diversity of biological organisation ranging from cellular macromolecules to biomes. Edward Wilson popularized the term ‘biodiversity’.

LEVELS OF BIODIVERSITY

• Genetic diversity: Diversity shown by a single species at genetic level. E.g. Rauwolfia vomitoria (Himalaya) shows genetic variation in the potency & concentration of the chemical reserpine. India has more than 50,000 different strains of rice and 1000 varieties of mango .
• Species diversity: Diversity at species level. E.g. Western Ghats have greater amphibian species than Eastern Ghats.
• Ecological diversity: Diversity at ecosystem level. E.g. In India, deserts, rain forests, mangroves, coral reefs, wet lands, estuaries & alpine meadows are seen.

NUMBER OF SPECIES ON EARTH (GLOBAL SPECIES DIVERSITY) o According to IUCN (2004) , more than 1.5 million species described so far. o According to Robert May’s Global estimate , about 7 million species would have on earth. (He considered the species to be discovered in the tropics. i.e. only 22% of the total species have been recorded so far). o Animals are more diverse (above 70%) than plants including Plantae and Fungi (22%) . o Among animals, insects are most species rich group ( 70% , i.e. out of every 10 animals, 7 are insects). o Number of fungi species is more than the combined total of the species of fishes, amphibians, reptiles & mammals.

o India has only 2.4% of world’s land area, but has 8.1% of the species diversity. India is one of the 12 mega diversity countries of the world. Nearly 45,000 plant species and twice as many of animals have been recorded from India. o Applying May’s global estimates, India would have more than 1 lakh plant species and 3 lakh animal species. o Biologists are not sure about total number of prokaryotic species because • Conventional taxonomic methods are not suitable for identifying microbial species. • In laboratory, many species cannot be cultured.

PATTERNS OF BIODIVERSITY i. Latitudinal gradients

• Species diversity decreases from the equator to the poles.
• Tropics (latitudinal range of 23.5o N to 23.5o S) have more species than temperate or polar areas. E.g. Number of bird species in different latitudes: o Colombia ( near equator): about 1400 species. o India (in tropics) : > 1200 species. o New York (41 o N): 105 species. o Greenland (71 o N): 56 species.
• Tropical forest region like Equador has up to 10 times of vascular plant species as compared to a temperate forest region like the Midwest of USA.
• Tropical Amazonian rain forest (South America) is the greatest biodiversity on earth. It contains o > 40000 species of plants o 3000 species of fishes o 1300 species of birds o 427 species of mammals o 427 species of amphibians o 378 species of reptiles o > 1,25,000 species of invertebrates
• Biodiversity (species richness) is highest in tropics because o Tropics had more evolutionary time. o Relatively constant environment (less seasonal). o They receive more solar energy which contributes to greater productivity.

ii. Species- Area relationship According to the study of Alexander von Humboldt in South American jungles, within a region, species richness increases with increasing explored area, but only up to a limit. Relation between species richness and area gives a

• On a logarithmic scale, the relationship is a straight line described the equation Log S = log C + Z log A
• Generally, for small areas, the Z value is 0.1 to 0.2 .
• But for large areas (e.g. entire continents), slope of the line is steeper (Z value: 0.6 to 1.2).
• E.g. for frugivorous birds and mammals in the tropical forests of different continents, the Z value is 1.15.

I MPORTANCE OF SPECIES DIVERSITY

• According to David Tilman, plots with more species shows less year-to-year variation in total biomass.
• Increased diversity contributes to higher productivity. It is essential for ecosystem health and survival of human race.
• ‘Rivet popper hypothesis’: It is an analogy used to understand the importance of biodiversity. It is proposed by Stanford ecologist Paul Ehrlich. In an airplane (ecosystem), all parts are joined with many rivets (species) . If passengers pop a rivet (extinction of a species), it may not affect flight safety (functioning of the ecosystem) . But as more and more rivets are removed, the plane becomes dangerously weak. Loss of rivets on the wings ( key species that drive major ecosystem functions) is more dangerous than loss of a few rivets on the seats or windows.

LOSS OF BIODIVERSITY

• IUCN Red List (2004) says that 784 species (338 vertebrates, 359 invertebrates & 87 plants) were extinct in the last 500 years. E.g. Dodo (Mauritius), Quagga (Africa), Thylacine (Australia), Stellar’s sea cow (Russia) and 3 subspecies (Bali, Javan, Caspian) of tiger.
• 27 species have been disappeared in the last 20 years.
• More than 15,500 species are facing threat of extinction.
• 12% birds, 23% mammals, 32% amphibians, 31% gymnosperm species face the threat of extinction.
• The current extinction rate is 100 – 1000 times faster than in the pre-human times. If this trend continues, nearly 50% species might be extinct within next 100 years. Impacts of Loss of biodiversity o Decline in plant production. o Environmental perturbations such as drought. o Increased variability in ecosystem processes such as plant productivity, water use and pest & disease cycles.

Causes of Biodiversity losses (‘The Evil Quartet’)

• Habitat loss and fragmentation: Most important cause.
• E.g. Tropical rain forests (loss from 14% to 6%).
• Thousands of hectares of rain forests are being lost within hours.
• The Amazon rain forest is being cut for cultivating soya beans or for conversion of grass lands for cattle.
• Fragmentation badly affects animals requiring large territories and migratory animals.
• Over-exploitation: Stellar’s sea cow, Passenger pigeon etc. extinct due to over exploitation.
• Alien species invasions: Alien species cause decline or extinction of indigenous species . E.g.
• Nile Perch introduced in Lake Victoria (East Africa) caused extinction of more than 200 species of cichlid fish.
• Invasive weed species like Parthenium (carrot grass), Lantana and Eicchornia (water hyacinth) caused damage to our native species.
• Illegal introduction of the African Catfish (Clarias gariepinus) for aquaculture is a threat to the indigenous catfishes in our rivers.
• Co-extinction: When a species becomes extinct, the species associated with it also extinct. E.g.
• Extinction of the parasites when the host is extinct.
• In co-evolved plant-pollinator mutualism , extinction of one causes the extinction of the other.

BIODIVERSITY CONSERVATION

There are 3 categories of reasons for conservation.

a. Narrowly utilitarian arguments

• Human derive economic benefits from nature such as food, firewood, fibre, construction material, industrial products (tannins, lubricants, dyes, resins, perfumes) and medicines.
• More than 25% of the drugs are derived from plants.
• 25,000 species of plants have medicinal value.

b. Broadly utilitarian arguments Biodiversity has many ecosystem services. E.g. • Amazon forest (‘lung of the planet’) produces 20% of total O 2 in the earth’s atmosphere. • Pollination through bees, bumblebees, birds and bats. • Aesthetic pleasures.

c. Ethical arguments • Every species has an intrinsic value . We have a moral duty to care for their well-being. Biodiversity conservation is 2 types: In situ (on site) conservation and Ex situ (off site) conservation.

a. In situ conservation (on site) It is the conservation of genetic resources within natural or human-made ecosystems in which they occur. E.g. Protected areas such as National Parks, Sanctuaries, Biosphere reserves, cultural landscapes, natural monuments etc. • National Park: Strictly reserved for the welfare of the wildlife where private ownership, cultivation, grazing etc. are prohibited. E.g. Eravikulam National Park in Kerala. • Sanctuary: Here, protection is given only to the animals. Collection of timbers, minor forest products and private ownership are allowed so long as they do not harm the animals. E.g. Periyar wildlife sanctuary in Kerala. • Biosphere Reserves: Areas of land or coastal ecosystems for conservation and sustainable use. • Sacred forests (Sacred groves): Forest fragments which are communally protected based on religious beliefs. E.g. o Sacred groves in Khasi & Jaintia Hills in Meghalaya. o Aravalli Hills of Rajasthan. o Western Ghat regions of Karnataka & Maharashtra. o Sarguja, Chanda & Bastar areas (Madhya Pradesh). India has 14 Biosphere Reserves, 90 National Parks and 448 wildlife sanctuaries.

b. Ex situ conservation (off site) It is the conservation of organisms outside their habitats. E.g. genetic resource centres, zoological parks, wildlife safari parks, botanical gardens, gene banks, cryopreservation etc. Hotspots • These are the regions with very high species richness, high degree of endemism (species confined only to a specific region) but most threatened. • There are 34 hotspots in the world. • 3 hotspots cover India’s biodiversity regions- Western Ghats & Sri Lanka, Indo-Burma and Himalaya. • All hotspots together cover only < 2% of the earth’s land area. But the species richness is extremely high. Protection of hotspots reduced the ongoing extinctions by 30%.

International Efforts for conserving biodiversity • The Earth Summit or Convention on Biological Diversity (Rio de Jeneiro, 1992) – 3 objectives: a. Conservation of biodiversity. b. Sustainable use of biodiversity. c. Sharing of benefits arising from genetic resources. • The World Summit on Sustainable Development (Johannesburg, South Africa, 2002): 190 countries pledged to reduce the current rate of biodiversity loss.

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Revision Notes for CBSE Class 12 Biology Chapter 1 (Biodiversity and Conservation) - Free PDF Download

An important grade, Class 12, is a crucial time for students and they are in pressure to perform well in the examinations. It is good to have notes handy for end time revision as well as clearing all doubts related to the subject. Here, we will learn about Biology that includes information about Class 12 Biology chapter 15 revision notes. NCERT book comprises various sections and topics and while preparing, it is easier if students get well-written notes with them. 

CBSE Class 12 Biology Biodiversity and Conservation revision notes can be easily available through online educational platforms. Students can access all major topics, subtopics and concepts on these platforms. It will help them to have rigorous study material for exam preparations. Often, students are worried and face nervousness while facing the paper despite good preparations. It is due to end moment anxiety but a good revision of the subject will help in this scenario. Revision notes Class 12 Biology Chapter 15 will be helpful for candidates to memorize the questions and answers thoroughly just before the big day.

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Biodiversity and Conservation Class 12 Notes Biology - Basic Subjective Questions

Section−a (1 mark questions).

1. What type of biodiversity is represented by the following? 

(i) The Amphibian population is richer in the Western Ghats than the Eastern Ghats.

(ii) Variation in the potency and concentration of the reserpine in Rauwolfia.

Ans. (i) Species diversity

(ii) Genetic diversity

2. How many species of plants and animals have been described by IUCN in 2004? What is global species diversity according to Robert May?

Ans. IUCN (2004) has described slightly more than 1.5 million species of plants and animals. According to Robert May’s estimates, the global species diversity is about 7 million.

3. Explain co-extinction with a suitable example.

Ans. When a species becomes extinct, the plant and animal species associated with it in an obligatory way also become extinct. This is known as co-extinction. Example- In plant-pollinator mutualism, extinction of one leads to the extinction of the other.

4. What is the IUCN red list?  

Ans. IUCN (International Union of conservation of nature and natural resources) maintains a “Red data list” which is a catalog of taxa facing the risk of extinction. 

5. What are endemic species?

Ans. Species exclusively confined to one region and nowhere else in the world are endemic species.

Section−B (2 Mark Questions)

6. What do you mean by species diversity? Name two measures of species diversity.

Ans. Species diversity refers to the variety of species within a particular region. The two important measures of species diversity are:-

(i) Species richness:- It refers to the number of species per unit area.

(ii) Species evenness:- It refers to the relative abundance of different species is represented in an area.

7. What are sacred groves? What is their role in conservation?

Ans. Sacred groves are forests and natural habitats that are protected through religious faith and worship, by the locals of a region. In many cultures, some forest tracts were set aside. The trees and wildlife within those tracts were venerated (considered holy) and given total protection. In some areas, the sacred groves are the last refuges for a large number of rare and threatened plants.

8. Give reasons as to why is it difficult to estimate global diversity for prokaryotes.

Ans. It is difficult to estimate the global diversity of prokaryotes because

(i) Conventional taxonomic methods are not suitable for identifying microbial species.

(ii) Many of these species are not culturable under laboratory conditions.

(iii) If biochemical and molecular biology techniques are used to delineate species, their diversity would run into millions.

9. List the important attributes of a stable community.

Ans. The important attributes of a stable community are:

(i) It must not show too many variations in the year–to–year productivity.

(ii) It must be either resistant or resilient to seasonal disturbances.

(iii) It must be resistant to invasion by alien species.

10. Give below is the graph for the species-area relationship.

Ans. Equation for curve ‘a’: S = CA Z  

Equation for curve ‘b’: Log S = log C + Z log A

S= Species richness

Z = Slope of the line (regression coefficient)

C = Y-intercept

11. Name any four approaches each for ex-situ conservation and in situ conservation as a strategy for biodiversity conservation.

Ans. In-situ conservation: Biodiversity hotspots, Sacred groves, Wildlife sanctuaries, Biosphere reserves.

Ex-situ Conservation: Zoological parks, Botanical garden, Arboretum, Gene bank.

PDF Summary - Class 12 Biology Biodiversity and Conservation Notes (Chapter 15)

Large and diverse communities of biota occupy distinct zone-forming ecosystems.

The term biodiversity was first coined by W.G. Rosen in the year 1980.

It is a shortened combination of two words- “biological” and “diversity”.

Biodiversity or biological diversity is often defined because of the vast diversity of species and sorts of all the life forms existing on earth. They include the species of microorganisms, algae, fungi, plants, animals, occurring on the earth in various habitats and the ecological complexes and niches of which they are apart.

Whether or not a species can survive and colonize a neighborhood depends on the environmental conditions of the world also because of the range of tolerance of the species.

Magnitude of Biodiversity

Approximately 45,000 species of plants and nearly twice as many species of animals are found in India. Therefore, India is said to be one of the 12 mega diversity-bearing countries on the planet.

Numerous species that are yet to be identified are believed to inhabit tropics and coral reefs. 

The number of species present in the tropics can be estimated by comparing species richness between tropics and temperate areas. Inventories are nearly complete for most groups of organisms in temperate areas. 

Scientists have calculated approximately 5.50 million species of organisms present in the world. 

The most interesting aspect of biodiversity is that more than ${ 70 }$% of all species are animals while plants account for only ${ 22 }$%. 

Among the animals, insects are the most numerous at about ${ 70 }$% with a present estimate of 7 out of 10 animals. 

The knowledge about protists, archaebacteria, and viruses is somehow less and with the help of that information, the magnitude of biodiversity will increase further.

Levels of Biodiversity 

1. Genetic Diversity 

It is the diversity in the number and type of genes as well as chromosomes present in different species and also the variations in the genes and their alleles in the same species. 

On average a bacteriophage has 100 genes, Drosophila melanogaster has 13000 genes, whereas the Homo sapiens has 30,000 – 40,000 genes. 

Variation in the genes of a species increases with the increase in size and environmental parameters of the habitat. 

Genetic diversity is useful in adapting to changes in environmental conditions. 

It helps in the speciation or evolution of new species. 

Lower genetic diversity within a species or variety is very much useful for uniformity in yield as well as higher yield.  

At the hands of fungal or insect attacks, the lower genetic diversity is more susceptible to degradation and prone to mass-scale destruction. 

2. Species Diversity 

It is the diversity and variety in the number and richness of the species of a particular region. 

Species richness is the number of species present per unit area. 

Species evenness or species equitability is represented by the number of individuals of different species in a given area. 

Those communities exhibit evenness where species are represented by more or less the same number of individuals. 

Communities where one or more species have more individuals than others show dominance or unevenness. 

The product of species richness or evenness or equitability is known as species diversity.  

Odum et al in the year 1960 calculated species diversity as several species per thousand individuals whereas Menhinick in the year 1964 calculated it as the number of species about the square root of a total number of individuals.

The Shannon index is the diversity index commonly used in ecological studies. 

3. Community and Ecosystem Diversity 

Community Diversity is of Three Types:

(i) Alpha diversity exists within community diversity. It is species diversity that is dependent upon species richness and evenness. Amongst the members of the same community, there is a lot of competition, adjustments, and inter-relationships. Here variations are limited. 

(ii) Beta diversity exists between communities. It appears along a gradient of habitat within the geographical area. Due to differences in microhabitat, niches, and environmental conditions, there may occur changes in communities that could lead to the replacement of species. 

(iii) Gamma diversity is the diversity that is present in ranges of communities as represented by the diversity of habitats or ecosystems over a total landscape of the complete geographical area. 

Ecosystem diversity is the variety of forms in the ecosystem due to the diversity of niches, trophic levels, and ecological processes like nutrient recycling, food webs, energy flow, the role of dominant species, and various biotic interactions. 

Diversity helps in attaining more productive and stable ecosystems which can tolerate various environmental stresses such as prolonged drought. 

India as Mega Diversity Region 

As India has been assigned the status of mega diversity nation it has attained a unique distinction. 

The country has 10 biogeographical regions. Trans Himalaya, Himalaya, Desert, Semi-arid, Western  Ghats, Deccan peninsula, Gangetic Plain, Coasts, North-East, and Islands belongs to the biogeographical regions of India.

India has 89 national parks, 492 wildlife sanctuaries, 14 biosphere reserves, 6 wetlands, and 5 world heritage sites. The country also has 27 tiger reserves. 

The largest biogeographical region is the Deccan peninsula and the Western ghat and northeast are regions richest in biodiversity. 

${ 33 }$% of flowering plants, ${ 10 }$% of mammals, ${ 36 }$% reptiles, ${ 60 }$% of amphibians, and ${ 53 }$% of freshwater fish are endemic. The Himalayas and the Western Ghats are the richest regions. Indian Islands and North-Eastern Hills

Patterns of Biodiversity Latitudinal and Altitudinal Gradients  

(i) Latitudinal Gradient 

There was little biodiversity at the poles. Biodiversity is more in temperate areas but it occurs maximum in tropical rainforests. This is because the tropical rain forests have more favorable conditions for more varieties of organisms and with fewer or no catastrophes. This has allowed for stability in the environment and also allowed more species to develop. 

Only during the cold season in temperate areas the harsh conditions exist. However, in arctic regions there remains very harsh conditions for most of the year.

In tropical forests, the number of vascular species is 118-236/0.1 ha, and in temperate forests 21-48 species 0.1 ha. Their number would be 10/0.1 ha in arctic regions.

(ii) Altitudinal Gradient 

As we ascend high mountains a decrease in species diversity occurs due to a drop in temperature and greater seasonal variability.

Species – Area Relationship 

Alexander von Humboldt, a German geographer, and naturalist observed that species richness within a region increases with the increasing area but only up to a certain limit. 

For a wide variety of taxa whether they are birds, bats, freshwater fishes, or flowering plants the relationship between species richness and area is a rectangular hyperbola. 

It is represented as a straight line on a logarithmic scale. 

Here species richness is represented by S,  the slope of the line or regression coefficient is represented by Z, C represents the y-intercept whereas A represents the area. 

The regression coefficient is generally 0.1-0.2, regardless of taxonomic group or region e.g. plants found in Britain, birds that are seen in  California, or mollusks that exist in New York.  

However, when the species-area relationship is considered for a very large area like the whole continent, the geographical retrogression coefficient or slope of the line will have a Z value of 0.6 – 1.2, e.g. frugivorous birds and mammals of tropical forests of different continents will represent a steeper line of 1.15. 

Importance of Biodiversity 

1. Source of Food 

Out of 3000 species of food plants, only 150 species have been commercialized. It can be seen that ${ 85 }$% of the food output is produced by less than 20 species. 

Two-third of food is being produced by only three crops that are rich in carbohydrates: wheat, corn or maize, and rice. 

Utilization of more and more food plants has to be made.

2. Source of fats and oils 

The major oilseed plants are soybean, coconut, cottonseed, peanut and sunflower, sesame, safflower, mustard, and oil palm. 

For obtaining high-performing lubricants some newer species of oil are being investigated. E.g. Bitter colocynth, and jojoba seed.

3. Fibres 

The major sources of fiber are cotton, jute, flax, hemp, sun hemp, rosella, coir, and agave. Search is continuously going on for new superior fiber yielding plants.

4. New Varieties 

Domesticated commercial species have been improved for various traits, especially disease resistance by crossing them with their wild relatives. 

Rice has been made resistant to four main diseases by crossing it with its wild species namely Oryza nivara from India. 

Potato has been made resistant to late blight (a trait from Solanum demissum), Potato Mosaic Virus Y (a trait from  Solanum stolonifera), Fusarium, and five races of cyst nematodes (a trait from Solanum spegazzini)

5. Drugs and Medicines 

Several drugs are based on plant products. 

Rosy periwinkle (Catharanthus roseus = Vinca rosea) yields alkaloids (Vincristine and vinblastine) which are useful for the treatment of leukemia. The same is now being synthesized chemically. 

Other drugs derived from plants are Morphine (Papaver somniferum for pains), quinine (from the bark of Cinchona ledgeriana for malaria), taxol (from the bark of Yew; Taxus brevifolia and Taxus baccata for treating cancers),  reserpine (from Rauwolfia serpentina for treating blood pressure and schizophrenia), etc. 

${ 25 }$% of all drugs are currently sourced from 120 species of plants. 

Traditional systems of medicine the world over use thousands of local or wild plants for treating various maladies. Plant chemicals are also called botany chemicals and it is possible to manufacture innumerable synthetic products from Plant chemicals.

6. Aesthetic Value 

Biodiversity features a lot of value in terms of aesthetics and attraction of individuals towards a specific place. Biodiversity's aesthetic value is frequently exploited in ecotourism, bird watching, wildlife conservation, pet ownership, and gardening.

7. Cultural Benefits  

Historically people have attached themselves to certain specific plants and animals.  

Many Indian homes have varieties of Ocimum sanctum (Tulsi) growing in the gardens and pots.  

Trees of Ficus religiosa commonly called Peepal and Prosopis cineraria known as Khejri are considered sacred. They are worshipped too.

Many birds are believed to be sacred. Snakes are also worshipped.  

Every country and state recognizes a particular plant and particular animal as a symbol of national and state pride and cultural heritage.  

8. Ecosystem Services  

Biodiversity is required to maintain and utilize products and services of various ecosystems and individual species.  

Forest and oceanic systems control climate and maintain the gaseous composition of the atmosphere.  

Amazon rain forests are considered the lungs of planet earth as they give out  ${ 28 }$% of total oxygen.  

Biodiversity is essential for natural pest control and the maintenance of populations of various species. It is very important for pollination by insects and birds, nutrient cycling, conservation and purification of water, formation, and protection of soil, etc. The services are valued at 16-54 trillion dollars per annum.

Threats to Biodiversity 

The world is facing an accelerated rate of species extinction, largely due to human interference. There are four major  causes which are also called the evil quartet: 

i) Habitat Loss and Fragmentation: -  

Overpopulation, urbanization, and industrialization require additional land every year.  

It can come through the destruction or fragmentation of natural habitat through filling wetlands, plowing grasslands, cutting down trees, burning a forest, and clearing some area of vegetation.  

Animals requiring large territories are badly affected.  

Migrating animals would surely go astray and must get killed.

ii) Overexploitation:-  

Excessive exploitation of a species, whether a plant or animal reduces the size of its population so that it becomes vulnerable to extinction.  

In the last 500 years three subspecies of Tiger, dodo, stellar sea cow, and passenger pigeon have become extinct due to overexploitation by humans.  

Nowadays several marine fish populations are declining around the world.

iii) Alien Species Invasions:-  

Non-native or alien species are often used inadvertently for their economic and other uses. Many times they become invasive and inhibit the growth and survival of local species.  

Island ecosystems are the most vulnerable. This is mainly because of their small size and a small number of species.  

Water hyacinth (Eichhornia crassipes) was introduced with the intent to reduce pollution in Indian waters.  

It has led to the clogging of water bodies including wetlands in many places. This has resulted in the death of several aquatic plants and animals.  

Nile perch may be a predator fish that was introduced in Lake Victoria of South Africa. it's since then killed and eliminated the ecologically unique diversity of over 200 native species of small cichlid

iv) Co-Extinctions:-  

Certain obligatory mutualistic relationships exist in nature e.g. Yucca moth and Yucca flower.  

The extinction of one will automatically cause the extinction of the other.  

If the host fish becomes extinct, all the parasites exclusively found on that will automatically become extinct.

Wildlife Conservation 

Wildlife conservation is necessary for a lot of reasons. 

i) Balance of Nature:  

In an ecosystem, there is a natural balance. The different types of living organisms live together in equilibrium.  

The food web consists of an interlocking system of the food chain, the destruction of any species of wildlife in an ecosystem can disrupt the entire balance of nature.

ii) Commercial value of Wildlife:  

We have a rich variety of wildlife. National parks and sanctuaries which were established by the Government will attract many tourists from abroad. This is a valuable source of foreign exchange.  

Surplus animals are sold to international zoos and parks, earning foreign exchange in the process.

iii) Biological studies: 

Naturalists, zoologists, and behavior biologists can study the ecology, physiology, and behavior of the varied sorts of wildlife in their natural habitats. This improves our knowledge of biology.

iv) Sports and Recreation: 

The sport of hunting is restricted to an excellent extent due to the rapidly declining number of animals. Good recreation is often provided within the sort of camping, trekking, and other adventure activities by wildlife centers.

Conservation of Biodiversity 

Conservation of biodiversity is considered under three categories 

A. Narrowly utilitarian 

B. Broadly utilitarian 

Narrowly Utilitarian 

Human beings obtain several direct economic benefits from nature. 

Food like cereals, pulses, fruits, etc., then firewood, fiber, construction material are obtained from nature.  

Industrial products such as tannins, lubricants, dyes, resins, perfumes are also made using natural products. 

Products of medicinal importance too. 

Bioprospecting is the method of exploring genetics and species-level diversity to get and develop products of economic importance.

Broadly Utilitarian 

Amazonian forests alone produce nearly ${ 20 }$% of oxygen during photosynthesis. 

Pollinator layer: bees, bumblebees, birds, and bats that pollinate the plant without which seed cannot be produced by plants.  

The aesthetic pleasure we get from the conservation of biodiversity.

Ethical:  

Humans depend on their existence to all other organisms that inhabit and have inhabited this earth.  

Each species and variety has its intrinsic value.  

It is our moral obligation to safeguard and pass on the biological legacy that we have been given.

Conservation of Biodiversity: 

There are two types of conservation strategies – in situ (on-site) and ex-situ (off-site) 

In situ Conservation  

It is the conservation and protection of the whole ecosystem and its biodiversity at all levels to protect the threatened species. It is however neither economically possible nor possible to conserve all existing biological wealth and all the existing ecosystems. 

Hot spots 

These are areas with a high density of biodiversity or megadiversity. These are also the most threatened ones. Ecological hot spots are determined by the following four factors: 

(i) Number of species or species diversity 

(ii) Degree of endemism 

(iii) Degree of threat to a particular habitat due to its degradation and fragmentation 

(iv) Degree of exploitation: 

Mayers (1988) initially identified 12 hot spots with ${ 14 }$% of plant species in an area of only ${ 0.2 }$%. 

Today the number of hotspots identified by ecologists is 34 covering an area of less than ${ 2 }$% of land surface with about ${ 20 }$% of the human population living there. 

India has three hot spots: Indo-Burma, Himalayas and the Western Ghats, and Srilanka. 

Protected Areas 

They are ecological or biogeographical areas where biological diversity is protected, maintained, and managed through legal or other effective measures along with natural and cultural resources. 

They are defined and delimited based on biological diversity e.g. cold desert in Thar, a wetland in Assam, saline swampy area of Sundarbans, etc. Protected areas involve national parks, sanctuaries, and biosphere reserves.

National Park 

They are government-managed areas set aside for the enhancement of wildlife cultivation. In National parks, human activities such as grazing, forestry, and habitat manipulation are not allowed. 

89 national parks in India occupy nearly ${ 1.1 }$% of the geographical area

Sanctuaries 

They are large swaths of land with or without lakes where wild animals and flora can hide from hunters. Certain other humans interfering activities such as the collection of forest products, harvesting of timber, private ownership of land, tilling of land, etc., are allowed.

Biosphere Reserves 

They have protected areas that have been designed for multiple purposes. They are created to preserve genetic diversity in representative ecosystems of various natural biomass and unique biological communities.  This is done by protecting wild populations, traditional lifestyles of tribal and domesticated plant and animal genetic resources. 

The creation of biosphere reserve was initiated in 1975 under the MAB program of UNESCO. 

Till the year 2002, there were 408 biosphere reserves had been established in 94 countries. 

In India, 17 biosphere reserves have been set up by now. 

Each biosphere reserve has:

i) Core or Natural zone: No human activity is allowed. The area is an undisturbed and legally protected ecosystem. 

ii) Buffer zone: It surrounds the core area. Human activities such as resource consumption, strategy development, and education is restricted.

iii) Transition zone: It is the outermost or peripheral part of the biosphere reserve where active cooperation is present between reserve management and local people for activities like settlements, cropping recreation, forestry, and other economic uses without making any disturbance to ecology.

The transition zone has different parts like forestry, agriculture, and tourism, and restoration regions. 

Restoration region is a degraded area that is selected for restoration to near natural form.

a. Importance of Biosphere Reserves Includes: 

i) Restoration – Biosphere reserves help in the restoration of degraded ecosystems and habitats. 

ii) Conservation – They aid in the conservation of genetic resources, animals, ecosystems, and landscapes while avoiding uprooting local populations.

iii) Development –By maintaining cultural, social, and ecological sanctity they ensure sustainable economic development. 

iv) Monitoring - Regular monitoring of development and conservation progress is necessary to be done. 

v) Education and Research –Each biosphere reserve promotes teaching and study in the ecosystem/different biome's ecological features. There is also an exchange of information about research, restoration, conservation, and development aspects at the national and global levels.

b. MAB Program 

Man and biosphere program is an international biological program of UNESCO which was started in 1971 but was introduced in India in 1986. 

MAB has studied the impact of human interference and pollution on abiotic and biotic components and develops conservation strategies for the present as well as the future. 

c. Ex-Situ Conservation 

These are means of conservation of any desired species or variety far away from their natural habitats. They are off-site collections.

They are live collections of untamed and domesticated species in botanical gardens, zoos, etc.

Currently, there are quite 1500 botanical gardens and arboreta (gardens with trees and shrubs) with quite 8000 species.

Many of them possess seed banks, tissue culture facilities, and other ex-situ technologies.

There are more than 800 zoological parks.

Together they need about 3000 species of mammals, birds, reptiles, and amphibians.

Most of them also have a well-managed captive breeding program.

Captive breeding is resorted to in those cases where the amount of surviving individuals is so small that there's no realistic chance of in-place survival.

As the number of surviving organisms increases, individuals are selectively released within the wild.

Offsite collection could also be used to replenish depleted populations, reintroduce wild species, and repair degraded habitats.

d. Gene Bank 

Seed banks, live growing plants (Orchards), tissue cultures, and frozen germplasm with the full range of genetic variety are all maintained by these institutes.

(i) Seed banks: Seeds are of two types- orthodox and recalcitrant.

Orthodox seeds are those which can tolerate a reduction in moisture content up to ${ 5 }$%, anaerobic conditions, and low temperature of to or even lower for prolonged periods e.g. cereals, legumes.

Seeds are allowed to germinate at intervals into plants and thus fresh seeds are developed for storage.

Recalcitrant seeds are those seeds that get killed on reduction of moisture and exposure to lower temperature e.g. Tea, cocoa, jackfruit, coconut.

They can be stored for a shorter duration after treatment with fungicides in rooms having air and normal oxygen.

(ii) Orchards: Orchards are grown from plants with recalcitrant seeds. At orchards, all possible strains and varieties are maintained e.g. Litchi, oil palm, rubber tree, etc.

(iii) Tissue culture: it's administered through callus formation, embryoids, pollen grain culture and shoot tip culture for those plants which are either seedless, have recalcitrant seed, variable seed progeny, or where a clone is to be maintained.

The method is beneficial in maintaining an outsized number of genotypes during a small area, rapid multiplication of species, and for hybrid rescue.

Shoot tip cultures are often wont to maintain virus-free plants. It is used for the international exchange of germplasm in cultures multiplied by vegetative methods. e.g. Banana, Potato.

(iv) Cryopreservation: Preservation at 196°C (liquid nitrogen) can maintain tissue culture, embryos, animal cells/tissue, and spermatozoa indefinitely.

Special processes are used to bring the cryopreserved material back to life when it is needed.

Biodiversity act (2002) 

To safeguard India's rich biodiversity and associated knowledge against misuse by foreign persons and organisations who do not share the advantages that result from such use, as well as to combat biopiracy.

Convention on Biodiversity

“The Earth Summit” held in Rio de Janeiro within the year 1992 called upon all nations to require suitable required measures for the conservation of biodiversity and sustainable utilization of its benefits.

In the World Summit on Sustainable development held in the year 2002 in Johannesburg, South Africa, 190 countries pledged their genuine commitment to achieving by the year 2010 a big reduction within the current rate of biodiversity loss at the worldwide, regional, and native level.

Convention on Biodiversity 

“The Earth Summit” held in Rio de Janeiro in the year 1992 called upon all nations to take suitable required measures for the conservation of biodiversity and sustainable utilization of its benefits. 

In the World Summit on Sustainable development held in the year 2002 in Johannesburg, South Africa, 190 countries pledged their genuine commitment to achieving by the year 2010 a significant reduction in the current rate of biodiversity loss at the global, regional, and local level.  

CBSE Class 12 Biology Revision Notes Chapter 15 - Biodiversity and Conservation

Class 12 biology chapter 15 revision notes preparation.

Class 12 Biology Chapter 15 revision notes online are prepared with the help of expert professionals who are updated with the latest edition of NCERT. Available in the form of PDF files, these can easily be downloaded from the online platform for free. Besides, students can fetch other related documents online through established educational platforms like Vedantu. Mock test papers, PQYP, sample papers, etc. are available through the internet. Students can practice all of the papers for giving their best shot during examinations. Having know-how about the paper structure, pattern, type of questions, and important topics is a great help for preparations.

Topics Covered in NCERT Class 12 Revision Notes Biology Chapter 15 Solution

Working on the following Class 12 notes Biodiversity and Conservation with the help of the revision plan will work wonders:

Introduction to Biodiversity and Conservation

Magnitude of biodiversity

Invertebrates, vertebrates and plants representing global biodiversity

Levels of biodiversity including genetic diversity, species diversity, community and ecosystem diversity, alpha diversity, beta diversity, gamma diversity

India as a mega diversity region

Patterns of biodiversity latitudinal and altitudinal gradients

Species-area relationship

Importance of biodiversity as a source of food, source of fats and oils, fibres, new varieties, drugs and medicines, aesthetic value, cultural benefits and ecosystem services

Threats to biodiversity that includes habitat loss and fragmentation, overexploitation, alien species invasions and co-extinctions

Wildlife conservation and its importance

Balance of nature, the commercial value of wildlife, biological studies and sports and recreation

Conservation of biodiversity

About narrowly utilitarian, broadly utilitarian and ethical practices

In Situ conservation

Hot spots and factors determining that include number of species, degree of endemism, degree of threat to habitat and degree of exploitation

Protected areas

National Park

Sanctuaries

Biosphere reserves

Transition zone

Importance of biosphere reserves that include restoration, conservation, development, monitoring and education and research

MAB program

Ex-situ conservation

Gene bank that includes seed banks, orchards, tissue culture and cryopreservation

Biodiversity Act (2002)

In addition to these briefly well-explained topics, students will also get access to multiple Youtube links for more understanding. All the topics mentioned in the above points are part of chapter 15- Biodiversity and Conservation and these are well explained briefly and with the help of charts, paragraphs, pointers, graphs, figures, and other highlights. It is easy to understand the approach for students who can give a quick look before their examination day and get all the information accessed on time.

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Class 12 Biology Chapter 1 Revision Notes 

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FAQs on Biodiversity and Conservation Class 12 Notes CBSE Biology Chapter 15 (Free PDF Download)

Q1. How do I study for  Chapter 15 of Class 12 Biology?

Ans: Students can avail PDF for NCERT Solutions and Revision Notes for Biodiversity chapter in Class 12th Biology at Vedantu. The massive course structure may overwhelm the students. Hence, the solutions and notes are designed by subject experts to aid the students in their preparations for their boards. The revision before examination is also made easier with the help of Notes for the chapter that incorporate all the important topics. The solutions and notes provided by Vedantu are free of cost. They are available on both Vedantu’s website(vedantu.com) as well as Vedantu Mobile app.

Q2. What is conservation of biodiversity according to Chapter 15 of Biology of Class 12?

Ans: Biodiversity is the variety of plants and animals on the planet. Biodiversity Conservation refers to the protection, upliftment and management of biodiversity i.e. plants and animals. This can be done by two methods:

In-situ Conservation: Sanctuaries, national parks, biosphere conservations and so on are in-situ biodiversity conservation where plants and animals are protected with boundaries within their natural habitat.

Ex-situ conservation: Zoological parks, botanical gardens, and the kind where endangered species of plants and animals are kept to maintain their numbering.

Q3. What are the reasons for the conservation of biodiversity according to Chapter 15 of Biology of Class 12?

Ans: Conservation of Biodiversity is important for the following reasons:

Plants and animals fulfil several basic and economic human needs.

They should be saved for our future generation.

Plants are our only source of oxygen.

Birds and animals are essential for pollination.

Humans derive a number of benefits from various plants like food, raw materials for construction, fibre and even medicine ingredients. It is not only essential to save the plants and animals for their uses but also for income generation.

Q4. What are the different types of biodiversity according to Chapter 15 of Biology of Class 12?

Ans: Biodiversity is categorized into three main types known as genetic biodiversity, species biodiversity, and ecological biodiversity. Genetic biodiversity is the distinction of individuals based on their genes. Species biodiversity distinguishes each community of species based on their characteristics. While ecological biodiversity includes all the diversity in a particular ecology of a region. Learn more about biodiversity and its types from Revision Notes for according to Chapter 15 of Biology of Class 12 by Vedantu.

Q5. How is biodiversity threatened according to Chapter 15 of Biology of Class 12?

Ans: The growing population has led to urbanization and an increase in industrialization. It results in the destruction of forests and plants and an upsurge in the number of stray animals. Hence, a growing danger to biodiversity. With time the demand for things derived from various diversities has increased leading to an imbalance in the ecosystem. If we do not take proper measures to save biodiversity it may be hazardous because every diversity has its own importance.

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Biodiversity and Conservation Class 12 Notes (Handwritten Short & Revision Notes)

Scoring higher marks in questions related to the Class 12 Biology chapter is not that difficult, it just needs proper understanding of topics with the help of Biodiversity and Conservation Class 12 notes and in practising a vast amount of questions. Through this students can build a strong foundation for the chapter Biodiversity and Conservation as well as it can be helpful in completing other chapters. 

Biodiversity and Conservation Class 12 Notes PDF

The Biodiversity and Conservation Class 12 notes PDF are so convenient for students that it is ready to use and learn; accordingly they can solve all the doubts as well as confusions regarding the chapter. Students can access the PDF from anywhere they want to and can complete the chapter Biodiversity and Conservation from their own place. 

Biodiversity and Conservation Class 12 Notes PDF Download links are given on this page as well as the steps to download the PDF are given below.

Where Can You Find Biodiversity and Conservation Class 12 Notes?

Students can find the Biodiversity and Conservation Class 12 notes from the Selfstudys website, steps to download are explained below: 

• Visit the Selfstudys website. 
• Bring the arrow towards the CBSE which can be seen in the navigation bar/ button. Select New Revision notes from the given list.

• A new page will appear, select Class 12th from the list of classes.

• Again a new page will appear, select the Biodiversity and Conservation to access the Notes. 

Things You Should Know About Biodiversity and Conservation Class 12 Notes

Before covering the chapter with the help of Biodiversity and Conservation Class 12 notes, students need to know everything about the class notes: 

• Free of Cost: While downloading the portable document format of Class 12 notes of the chapter Biodiversity and Conservation, students don’t need to pay any amount.
• Availability of Simple Language: The content in the Class 12 Biodiversity and Conservation notes provides simple language that students can understand the first time while they read or hear. 
• Explained in a Point Wise Manner: The topics and concepts explained in the Class 12 Biology Biodiversity and Conservation notes are explained in a point wise manner; through this students can also score in advanced topics. 
• All Topics are Covered: In the PDF of Class 12 Biodiversity and Conservation notes, all topics are covered in a genuine way so that students don't get stuck in any of the topics. 
• For CBSE Board: The Class 12 chemistry Biodiversity and Conservation notes is designed in such a way that students from CBSE can benefit the most. 
• Colourful Diagrams are Given: In the Class 12 Biology Biodiversity and Conservation notes, colourful diagrams are given; this can influence many students to complete the chapter. 

Why Is Biodiversity and Conservation Class 12 Notes Important?

It is very important for students to complete the chapter with the help of notes as it provides many benefits, those benefits are: 

• Helps to Improve Focus: The Biodiversity and Conservation Class 12 notes PDF helps to improve focus during the class; with this students can easily understand topics. 
• Boosts Comprehension Skills: All the topics and concepts in the Class 12 Biodiversity and Conservation notes are explained in a comprehensive way; through this students can also improve their comprehension skills while attempting the questions. 
• Helps to Extend Attention Span: The Class 12 Biodiversity and Conservation notes helps to increase attention span: ability to remain interested; accordingly students can score well in questions. 
• Improves Organisation Skills: The notes of Biodiversity and Conservation Class 12 are arranged in systematic and organised manner; through this students can increase their organisation skills. 
• Increases Creativity Skills: The Class 12 Biology Biodiversity and Conservation notes helps students to improve their creativity skills; accordingly they can absorb the knowledge more easily and quickly. 
• Promotes Active Learning: By going through the Class 12 notes of the chapter Biodiversity and Conservation, students can be actively involved in the learning process; thus it helps students to increase their productivity. 

When Should Students Use the Biodiversity and Conservation Class 12 Notes?

Students can use the Biodiversity and Conservation Class 12 notes whenever they want to, as it is an extra help for them to score good. Some general guidelines of when to use these notes are given below: 

• To Prepare for Test: Usually the Class 12 notes for the chapter Biodiversity and Conservation provides a short summary which includes important concepts for students; accordingly they can take the help of notes while preparing for tests.  
• To Revise: Students can take a look at Class 12 Chemistry Biodiversity and Conservation notes during the last minute revision; through this they can memorise the key concepts on the fingertips. 
• To Understand Topics and Concepts: To understand topics and concepts of the chapter Biodiversity and Conservation, students can seek the help of Class 12 Biology Notes as all topics are explained in a brief way. 
• After the Class: Students can take the help of notes of Biodiversity and Conservation Class 12 after completing each class; through this they can form a strong foundation for that topic completed during the class. 
• To Practise Questions: It is a must for students to practise vast amounts of questions, for this they can take the help of Class 12 Biodiversity and Conservation notes as in it questions are mentioned referring to the Previous Year Question Papers as well as CBSE Class 12 Sample Papers.
• Before Class: Students can take the help of Class 12 notes before going to the class of Biodiversity and Conservation; through this students can have a basic understanding of the chapter. 

Strategies to Cover the Chapter Chemical Reaction and Equation with the Help of Class 12 Biology Notes

Strategies is a perfect plan used to achieve any task; the same is applied to complete the chapter Biodiversity and Conservation with the help of Class 12 Biology notes, some of the basic tips are discussed below: 

• Set a Study Schedule As Per Priority: While completing the Biodiversity and Conservation Class 12 notes, students need to set a study schedule as per the priority for important topics as well as high weightage topics; accordingly by completing it they can get better results. 
• Don’t Keep Those Things Which Can Distract: Students are advised not to keep those things near them which can distract them like Comic book, portable video games, etc. while covering the Class 12 Biology Biodiversity and Conservation notes. Instead, they should keep important things near them like laptop, notebook, syllabus, highlighter etc. 
• Change Location As Per the Needs: Students can change the particular location as per their needs while completing notes of Biodiversity and Conservation Class 12; this can help them to stay attentive while completing the chapter. 
• Create a Good Sleep Schedule: While completing the chapter Biodiversity and Conservation with the help of Class 12 notes, students are advised to create a sleep schedule of at least 8 hours so that they can improve their memorisation skills.  
• Analyse the Repeated Questions: After completing the Class 12 Biology Biodiversity and Conservation notes, students are advised to analyse the repeated questions or frequent questions related to the chapter so that they can improvise the overall score. 
• Seek Help: If students are facing doubts while completing the Class 12 Biodiversity and Conservation notes, they can seek the help from concerned teachers and can easily solve confusions.  

6 Ways Biodiversity and Conservation Class 12 Notes Can Change Student’s Preparation

The Biodiversity and Conservation Class 12 notes can change student’s preparation in following ways: 

• Helps to Improve the Grip: The Class 12 Biodiversity and Conservation notes explains the concepts in a comprehensive way; this in turn can improve the grip as well as can impact the student’s preparation. 
• Improves the Clarity of the Concepts: The notes of Biodiversity and Conservation Class 12 improves the clarity and understanding of the concepts; this can help students to learn the topics and concepts effectively. 
• Improves Problem Solving Skills: Each topic and concept in the Class 12 notes of the chapter Biodiversity and Conservation are explained according to the weightage; this can automatically increase problem solving skills of a student as they will be able to practise in how many words an answer should be. 
• Saves Time: The Biodiversity and Conservation Class 12 notes are provided in the portable document format which saves time of both students and teachers as it is ready made. Accordingly, students can implement those saved time in the preparation process. 
• Improves Confidence: With the better understanding of topics through the Class 12 notes of the chapter Biodiversity and Conservation as well as solving questions can help students to improve their confidence.
• Accessible Anytime: The Class 12 Biology Biodiversity and Conservation notes can be accessible anytime and anywhere which means students can study at their own pace and convenience; this can lead to better performance. 

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Class 12 Biodiversity and Conservation Handwritten Notes PDF Download: Students can download all chapter wise notes of class 12 Chapter 15 Biodiversity and Conservation. We have collected and uploaded the PDF file for each chapter’s handwritten notes for class 12 Biodiversity and Conservation. We have also collected Class XII Handwritten notes for all subjects from the links provided in this article.

To score high marks in Biodiversity and Conservation, students need to memorize the formulas by heart. One way of doing so is going through the Biodiversity and Conservation notes for class 12 thoroughly. These formulas would not only help the student to achieve a high score in school exams, but also in CBSE Class 12 Biodiversity and Conservation Board Exam.

Class 12 Chapter 15 Biodiversity and Conservation Handwritten Notes PDF

Preparing for Class XII board exams is one of the biggest concerns for every student. And to help students in solving this issue we have prepared Biodiversity and Conservation handwritten notes for Class 12 Preparation. All these Class 12 Biodiversity and Conservation handwritten notes PDF are prepared by experienced teachers who have complete knowledge of the Biodiversity and Conservation subject. Chapter-wise important 12 class Biodiversity and Conservation handwritten notes for exam preparation and quick revision. The Biodiversity and Conservation study material includes most weightage chapters and their topics which will prominently be asked in the exam. The syllabus of the Class 12 Biodiversity and Conservation section includes complex topics that are quite difficult to manage with less time of exam preparation. To overcome this difficulty we have come up with the Biodiversity and Conservation important handwritten notes which help you focus only on major topics of the chapters. Check all notes & download their Class 12 Biodiversity and Conservation handwritten notes from the list shared below.

Class 12 Biodiversity and Conservation Notes Details

Importance of class 12 biodiversity and conservation handwritten notes pdf.

Just go through 4-5 times in Class 12 Biodiversity and Conservation handwritten notes per day and we bet you’ll end up retaining maximum facts. Along with the formulae and facts, we have also compiled some interactive examples and illustrations which have been picked up from the previous year papers of IIT JEE and other engineering exams. We’ll keep on adding more topics on a daily basis and you are also free to share your suggestions on the notes. You may also suggest a particular topic on which you would like us to present the Class 12 Chapter 15 Biodiversity and Conservation handwritten notes. Some of the benefits of these exclusive Biodiversity and Conservation Handwritten notes for Class 12 Mains include:

• Prepared by dexterous and adroit faculty consisting of ex-IITians.
• Based on the latest syllabus of Class 12 and other engineering exams.
• Cover almost all important facts and formulae.
• They have been presented in the most crisp and precise form.
• Easy to memorize.
• Supported with illustrations from past year papers.
• The solutions are elaborate and easy to understand.
• These Class XII Biodiversity and Conservation handwritten notes can aid in your last-minute preparation.
• These Class 12 Biodiversity and Conservation handwritten notes can actually help you improve your scores!!

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• Visit the website of hsslive .
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Class 12 Biodiversity and Conservation Chapter Wise Handwritten Notes PDF

Chapter-wise Class 12 Biodiversity and Conservation handwritten notes for exam preparation and quick revision. These Biodiversity and Conservation Notes PDF are very helpful for students who prepare for Jee Mains and Advanced without Coaching and Also helpful for Coaching Students. These Class 12th Biodiversity and Conservation Handwritten Notes are Prepared by the Best Jee Mains Faculty and are very Helpful for Crack Jee Mains Exam. Here is a break up of the topics Class 12 in the Biodiversity and Conservation chapter wise handwritten notes and syllabus.

Class 12th Biology All Chapter Handwritten Notes

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Students often face stress when the examinations are just round the corner but our Class 12 Biodiversity and Conservation Handwritten notes will help you guys in reducing that stress. Moreover, as the exams approach, it is not the subject matter that you need but it is the final revision that would prove to be of immense help. Revision is not just reading through the Biodiversity and Conservation handwritten notes you made in class. In fact, revision should include all the essential tips, be it theory or practical that would help you in attempting questions with ease.

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CLASS 12 NOTES

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NCERT Solutions Biodiversity and Conservation class 12 notes PDF

biodiversity and Conservation class 12 notes, Biodiversity and Conservation, in situ and ex-situ conservation of biodiversity, biodiversity and conservation class 12, biodiversity and conservation class 12 notes,

Table of Contents

biodiversity and Conservation class 12 notes 

Biodiversity and conservation class 12 notes.

1. Biodiversity is the term used to describe the total variety of biological organisations at all levels. The diversity is seen at all levels from organic molecules to ecosystems to biomes. The three most important levels of biodiversity are

(i) Genetic diversity A single species might show high diversity at the genetic level in terms of the number of chromosomes (or genes) and variation in genes (allelic forms) even in different members of the same species, e.g., The human, Homo sapiens-30000-40000 Number of genes in an E. coli-4000 In fruit fly, Drosophila melanogaster- 13000

(a) The genetic variation (in terms of allelic forms of the same gene) is expressed by the medicinal plant Rauwolfia vomitoria growing in different Himalayan ranges in terms of the potency and concentration of the active chemical (reserpine) that the plant produces.

(b) India has more than 50000 genetically different strains of rice and 1000 varieties of mango. 

(c) Genetic diversity affects the adaptability and capability of a species to survive in diverse habitats. It may help in speciation (evolution into new species).

(ii) Species diversity refers to the number and distribution of species in an area.

(a) It is expressed in terms of the number of species per unit area’ and also as the number of individuals of different species in an area. 

(b) e.g., the Western Ghats have a greater amphibian species diversity than the Eastern Ghats. Species diversity is the trait of a community and influences the interactions and stability of the community. 

(iii) Ecological diversity refers to the diversity at the ecosystem br level. This can include a variety of habitats, trophic levels, food webs, ecological processes and biotic interactions, etc. Ecosystem diversity makes communities more productive and stable.

now e.g., India has a greater ecosystem diversity (in terms of variety of habitats in deserts, rain forests, mangroves, coral reefs, wetlands, estuaries and alpine meadows) than a Scandinavian country like Norway.

2. According to the IUCN ( 2004), more than 1.5 million species have been recorded in the world and there might be about 6 million species on Earth waiting to be discovered and named. 

(i) Out of the total animals recorded, 70 % are insects. It means that out of every 10 animals on this planet, 7 are insects.

(ii) The group fungi has more species than all the vertebrate species (fishes, amphibians, reptiles and mammals) combined.

(iii) Nearly 45000 species of plants and about 90000 animals have been recorded from India. It is one of the 12 mega-diversity countries of the world. (iv) It is interesting to know that the diversity of microbial species alone might run into millions.

3. Patterns of Biodiversity The diversity of plants and animals, throughout the world, is not evenly distributed and shows some interesting patterns of distribution.

(i) Latitudinal gradients mean that species diversity decreases as we move away from the equator towards the poles.

(a) Generally, the tropics (latitudinal range of 23.5°N to 23.5°S) have more species than temperate or polar areas.

(b) The largely tropical Amazonian rain forest in South America has the greatest biodiversity on the Earth with more than 40000 species of plants, 3000 fishes, 1300 birds, 427 mammals, 427 amphibians, 378 reptiles and more than 125000 invertebrates.

(c) Some hypotheses proposed by scientists to explain the rich biodiversity in the tropics and less in temperate regions are:

The temperate regions were subjected to frequent glaciations in the past, whereas tropical latitudes have remained relatively undisturbed for millions of years and thus, had a long evolutionary time for species diversification.

Tropical environments provide continued favourable seasons that are relatively more constant and predictable. Such a constant environment promotes niche specialisation and leads to a greater species v diversity.

Availability of more solar energy in the tropics, boda contributes to higher productivity; this in turn might contribute indirectly to greater diversity.

(ii) Species-area relationships A German naturalist and geographer Alexander von Humboldt observed that within a region species richness increased with the increasing available area, but only up to a limit. 

(a) The relation between species richness and area, for a la wide variety of taxa (angiosperm plants, birds, bats, freshwater fishes) is a rectangular hyperbola. On a logarithmic scale, the relationship is a straight line described by the equation log Showing a species-area relationship. 

Note that on a log scale, the relationship becomes linear

where, S = species richness, A= area, Z = slope of the line (regression coefficient) and C=Y-intercept. 

(b) But, the ‘species-area’ relationships among very large areas like the entire continents, will give a much steeper slope of the line (Z values in the range of 0.6 to 1.2), e.g., for frugivorous (fruit-eating) birds and mammals in the tropical forests of different continents, the slope is found to be 1.15.

4. The Importance of Species Diversity to the Ecosystem Species diversity is important in terms of the following:

(i) Stability Communities with more species diversity, generally, tend to be more stable than those with less bo in species. This is because such communities are more resistant or resilient to occasional disturbances (natural or

man-made) and to invasions by alien species. 

(ii) Productivity Ecosystems with higher species diversity are much more productive, e.g., tropical forests. David Tilman’s long-term ecosystem experiments showed

that increased diversity contributed to higher productivity. 

(iii) Ecosystem health No species can exist independently Interactions among species ensure good health and stability,

5. Ecologist Paul Ehrlich gave an analogy rivet popper hypothesis to help understand the species. He compared each species with each rivet in the body of the aeroplane. 

(i) This hypothesis explains that the ecosystem is an aeroplane and the species are the rivets joining all parts together. 

(ii) If every passenger travelling in the aeroplane starts taking rivets home (causing a species to become extinct), initially it may not affect flight safety (properly removed, over some time, the plane becomes weak. 6. Loss of Biodiversity

(iii) The IUCN Red List (2004) documents the extinction of 784 species (including 338 vertebrates, 359 invertebrates and 87 plants) in the last 500 years.

(ii) Some examples of recent extinctions include the dodo (Mauritius), quagga (Africa), thylacine (Australia), Steller’s Sea Cow (Russia) and three sub-species (Bali, Javan, Caspian) of tiger.

(iii) The last twenty years alone have witnessed the disappearance of 27 species.

(iv) 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.

(v) The loss of biodiversity in a region may lead to

(a) Decline in plant production. 

(b) Lowered resistance of plants to environmental conditions like drought, etc.

(c) Negative impact on ecosystem processes such as plant productivity, water use pest and disease cycles. 

(D) Lowered plant productivity means loss of economically important materials for human usage and low food availability.

7 . The Causes of Biodiversity Loss are  

(i) Habitat loss and fragmentation Population explosion, air pollution, urbanisation and industrialisation have Tudestroyed forest land, which meant the loss of habit for several species, e.g.,

Once covering more than 14% of the Earth’s of beta land surface, the Amazonian rain forests now cover less than 6% as they are being cut and cleared for cultivation or conversion to grasslands for raising beef cattle. This has caused a loss of habitat for lots of species and has put tremendous pressure on the ecosystem.

(ii) Over-exploitation Uncontrolled overuse leads to A over-exploitation of natural resources and animals which harms the species. e.g., Many species extinctions in the last 500 years (Steller’s sea cow, passenger pigeon), many marine fish

populations were due to over-exploitation by humans. 

(iii) Alien species invasions When alien species are introduced unintentionally or deliberately in a habitat, some of them can cause the decline or extinction of indigenous species, e.g., Extensive environmental damage caused and the threat posed to our native species by invasive weed species like carrot grass (Parthenium), Lantana and water hyacinth (Eichhornia). 

(iv) Co-extinctions When a species becomes extinct, the plant and animal species associated with it, in an obligatory way, also become extinct, e.g., When a host fish species becomes extinct, its parasites also vanish. 8. Biodiversity Conservation There are several reasons that can be grouped into three categories narrowly utilitarian, broadly utilitarian and ethical.

(i) The narrowly utilitarian arguments for conserving biodiversity are that humans derive numerous direct economic benefits from

(a) food product (cereals, pulses and fruits).

(b) firewood.

(c) fibre (cotton, jute from plants and silk, wool from animals).

(d) construction material (timber for making furniture, houses, and sports goods).

(e) industrial products (tannins, lubricants, dyes, resins, perfumes).

(f) products of medicinal importance (about 25000 plants used in traditional medicine). (ii) The broadly utilitarian view is that biodiversity plays a major role in many ecosystem services that nature provides.

(a) Pure oxygen The Amazon forest is estimated to produce, through photosynthesis, 20% of the total oxygen in the Earth’s atmosphere.

(b) Pollination without which plants cannot give us fruits or seeds, is another service, ecosystems provide through pollinators-butterflies, bees, bumblebees, birds and bats.

(c) Flood and soil erosion control occur due to plants which help water retention, percolation and prevent soil erosion.

(d) Nutrient replenishment is due to plant biomass that falls on the ground being the biggest source of recycled nutrients after decomposition. 

• (e) Waste recycling by microbes and other insects, etc.

(f) Aesthetic pleasure that we derive from nature.

(iii) The ethical argument for conserving biodiversity relates to our moral obligation to conserve the planet that we share with millions of plant, animal and microbe species.

(a) We need to realise that every species has an intrinsic bot to value, even if it may not be of current or any economic value to us. 

(b) We have a moral duty to care for their well-being and pass on our biological legacy in good order to future ninth generations.

9. Conservation of biodiversity means protection, judicious and minimal use and rebuilding the damaged units. There are two basic approaches to the conservation of biodiversity. These are in situ conservation and ex-situ conservation.

(i) In situ conservation involves the protection of species in their natural habitat. 

(a) Hot spots are regions of high levels of species richness and a high degree of endemism. Endemic species are confined only to a limited region. There are 34 hotspots in the world. Three of these Hotspots in India are the Western Ghats and Sri Lanka Indo-Myanmar Eastern Himalaya-cover-our country’s exceptionally high biodiversity regions.

(b) Protected areas are ecologically unique and biodiversity-rich regions that are legally protected as biosphere reserves, national parks and sanctuaries. India has 14 biosphere reserves, 90 national parks and 448 wildlife sanctuaries.

There were areas in forests that were set aside and all the trees and wildlife within were venerated and given total protection. Such sacred groves are found in Khasi and Jaintia Hills in Meghalaya.

Aravalli Hills of Rajasthan. Western Ghat regions of Karnataka, Maharashtra.

The Sarguja, Chanda and Bastar areas of Madhya Pradesh. Meghalaya.

(ii) Ex situ conservation is the approach in which threatened animals and plants are taken out from their natural habitat and placed in special settings, where they can be protected and given special care. 

(a) Zoological parks, botanical gardens and wildlife safari parks are used for ex-situ conservation.

(b) many animals have become extinct in wildlife but continue to be maintained in zoological parks. 10. Scientific technology has enabled ex-situ conservation in the following ways:

(i) Cryopreservation of gametes of threatened species and keeping them preserved in viable and fertile conditions for long periods at very low temperatures.

(ii) In vitro fertilisation to propagate endangered species. Offsprings can be produced by using preserved sperm to fertilise the eggs in vitro and then implanted in female animals.

(iii) Tissue culture can be used to propagate plant species. 

(iv) Seed banks seeds of different genetic strains of commercially important plants can be kept for long periods, under specific conditions. Conventions on Biodiversity

(i) The historic convention on biological diversity (the Earth Summit) held in Rio de Janeiro in 1992, called upon all nations to take appropriate measures for the conservation of biodiversity and sustainable utilisation of its benefits.

(ii) The World Summit on Sustainable Development held in 2002 in Johannesburg, South Africa, 190 countries pledged their commitment to achieving by 2010, a significant reduction in the current rate of biodiversity loss at global, regional and local levels.

biodiversity and conservation class 12 Notes – Exercises

Question 1. Name the three important components of biodiversity.

Answer Three important components of biodiversity are genetic, species and ecological diversity.

Question 2. How do ecologists estimate the total number of species in the world?

Answer Ecologists make a statistical comparison of the species richness of systematically studied groups of insects of the temperate and tropical regions and extrapolate this ratio to other groups of animals and plants. It is to calculate the gross estimate of the total number of species existing on this planet.

Question 3. Give three hypotheses for explaining why tropics show the greatest levels of species richness.

Answer The three hypotheses for explaining why tropics show the greatest levels of species richness are 

(i) Speciation is generally a function of time and environmental stability. The temperate regions were subjected to frequent glaciations in the past, whereas tropical latitudes have remained relatively undisturbed for millions of years and thus, had a long evolutionary time for species diversification. 

(ii) Tropical environments provide continued favourable seasons that are relatively more constant and predictable. Such a constant environment promotes niche specialisation and leads to greater species diversity.

(iii) Availability of more solar energy in the tropics contributes to higher productivity; this in turn might contribute indirectly to greater diversity. 

Question 4. What is the significance of the slope of regression in a species-area relationship ? 

Answer When the analysis of a species-area relationship is done, amongst small areas, the values of slopes of regression are similar, irrespective of the taxonomic group or the region.

Nevertheless, when such an analysis is done amongst large areas, like continents, the slope of regression would be much steeper.

Question 5. What are the major causes of species losses in a geographical region?

Answer The major causes of species losses in a geographical region

(i) Habitat loss and fragmentation are:

(ii) Over-exploitation of natural resources.

(ii) Alien species invasions can cause the decline or extinction of indigenous species.

(iv) Co-extinctions When a species becomes extinct, the plant and animal species associated with it, in an obligatory way, also become extinct. 

Question 6. How is biodiversity important for ecosystem functioning?

Answer Biodiversity plays a major role in many ecosystem services that nature provides. 

(i) Pure oxygen The Amazon forest is estimated to produce, through photosynthesis, 20% of the total oxygen in the Earth’s atmosphere. 

(ii) Pollination without which plants cannot give us fruits or seeds, is another service, ecosystems provide through pollinators – butterflies, bees, bumblebees, birds and bats. 

(iii) Flood and soil erosion control plants help water retention, percolation and prevent soil erosion.

(iv) Nutrient replenishment plant biomass that falls on the ground is the biggest source of recycled nutrients after decomposition. en

(v) Waste recycling by microbes and other insects, etc., without which the Earth would simply become a huge pile of garbage and polluting material. 

(vi) Aesthetic pleasure that we derive from nature, by walking through thick woods, watching spring flowers in full bloom or waking up to a bulbul’s song in the morning.

biodiversity and conservation neet questions

Question 1. What characteristics make a community stable?

Answer The characteristics that make a community stable are 

(i) Less variation in productivity from year to year.

(ii) Resistance or resilience to occasional disturbances (natural man-made). 

(iii) Resistance to invasions by alien species. or

Question 2. What could have triggered mass extinctions of species in the past?

Answer Nobody knows the real reason but scientists believe that any one of the following could have triggered mass extinctions of species in the past

(i) Fall of sea levels.

(ii) Change of temperatures (freezing or warming).

(iii) Asteroid/meteorite hitting the planet. (iv) Poisonous hydrogen sulphide emissions from the seas. Nova/supernova/gamma-ray burst.

(vi) Plate tectonics.

Question 3. What accounts for the greater ecological diversity of India?

Answer The greater ecological diversity of India is because of the geographical diversity in terms of varying topography, e.g., deserts, rain forests, mangroves, coral reefs, wetlands, estuaries and alpine meadows. This results in the building of a different variety of ecosystems.

Question 4. What does ‘Red’ indicate in the IUCN Red list (2004)? 

Answer ‘Red’ indicates the taxa at the highest risk of extinction.

Question 5. Explain as to how the protection of biodiversity hot spots alone can reduce up to 30% of the current rate of species extinction.

Answer The biodiversity hotspots are regions with very high levels of species richness. These regions can be protected as biological reserves, national parks and sanctuaries.

Question 6. How does species diversity differ from ecological diversity? 

Answer Species diversity refers to the number and distribution of species in an area. It is expressed in terms of the ‘number of species per unit area’ and also as the number of individuals of different species in an area. Ecological diversity refers to the diversity at the ecosystem level. This can include a variety of habitats, trophic levels, food webs, ecological processes and biotic interactions, etc.

Question 7. Define gene pool.

Answer Gene pool refers to the total of genes of every y individual in an interbreeding population.

Question 8. What does the term ‘Frugivorous’ mean?

Answer The term ‘Frugivorous’ refers to fruit-eating birds.

Question 9. Define the terms (i) Bioprospecting and (ii) Endemism.

(i) Bioprospecting is a term that describes the process of discovery and commercialisation of new products based on biological resources. 

(ii) Endemism refers to a phenomenon of the presence of some species in particular regions only and nowhere else. 

biodiversity and conservation class 12 ncert solutions

Question 1. Of the four major causes for the loss of biodiversity (Alien species invasion, habitat loss and fragmentation, over-exploitation and co-extinctions which according to you is the major cause for the loss of biodiversity? Give reasons in support.  

Answer The major causes of the loss of biodiversity are

(i) Habitat loss and fragmentation caused by clearing and overexploitation of forest areas for agriculture, urbanisation and industrialisation. 

(ii) Increasing human population has overburdened the forest resources and has destroyed forest land, which meant the loss of habitat for several species. 

(ii) In addition, large habitats are broken up into small fragments because of which mammals and birds requiring large territories and with migratory habits are badly affected, leading to population decline.

Question 2. A species-area curve is drawn by plotting the number of species against the area. How is it that when a very large area is considered the slope is steeper than that for smaller areas?

Answer In very large areas, the number of species is much which is why the curve is much steeper. This is because the area is more, the food availability and other resources are much greater, so obviously more species can thrive.

Question 3. Is it possible that the productivity and diversity of a natural community remain constant over some time of, say one hundred years?

Answer Yes, the productivity and diversity of a natural community may remain constant over the period provided.

(i) The natural habitat is maintained. 

(ii) reasonably abundant resources are available.

(iii) environmental conditions for survival and conducive. 

All these factors encourage healthy interaction between species and the environment leading to continuous productivity and proliferation.

Question 4. What criteria should one use in categorising a species as threatened?

Answer The criteria that should be used in categorising a species as threatened are

(i) numbers of the members of the species are declining at an alarming rate.

(ii) their habitat is being modified or destroyed.

(iii) predator or poacher activities are increasing.

Question 5. What could be the possible explanation for the greater vulnerability of amphibians to extinction as compared to other animal groups?

Answer This is because of

(i) Habitat modification or destruction Amphibians generally need aquatic and terrestrial habitats to survive; threats to either habitat can affect populations. Hence, amphibians may be more vulnerable to habitat modification than organisms that only require one habitat type

(ii) Habitat fragmentation which means the isolation of a few areas by habitat modification. Small populations that survive within such fragments are often susceptible to inbreeding, genetic drift or extinction due to small fluctuations in the environment.

(iii) Large-scale climate changes can further modify aquatic habitats, preventing amphibians from spawning. 

Question 6. Humans benefit from the diversity of life. Give two examples.

(i) Humans derive numerous direct economic benefits from a diversity of organisms. 

• (a) Food product (cereals, pulses and fruits).
• (b) Firewood.
• (c) Fibre (cotton, jute from plants and silk, wool from animals). 
• (d) Construction material (timber for making furniture, houses and sports goods).
• (e) Industrial products (tannins, lubricants, dyes, resins and shed perfumes): 
• (f) Products of medicinal importance (about 25000 plants used in traditional medicine). you

(ii) There are huge intangible benefits that humans derive from the diversity of life. 

• (a) Pure oxygen.
• (b) Natural pollinators.
• (c) Flood and soil erosion control. 
• (d) Nutrient replenishment.
• (f) Aesthetic pleasure and mental peace.

Question 7. List any two major causes other than anthropogenic causes of the loss of biodiversity. 

Answer The two major causes other than anthropogenic causes of the loss of biodiversity are

(i) Alien species invasions When alien species are introduced unintentionally or deliberately in a habitat, some of them can cause the decline or extinction of indigenous species.

(ii) Co-extinctions When a species becomes extinct, the plant and animal species associated with it, in an obligatory way, also become Textinct.

Question 8. What is an endangered species? Give an example of an endangered plant and animal species.

Answer An endangered species is a population of organisms that is facing a high risk of becoming extinct because of

(i) Its numbers are very low. 

(ii) It is threatened by changing environment.

(iii) It is facing predator threat. et disenchant

Endangered plant species– Venus fly trap Endangered animal species- Siberian tiger

Question 9. Suggest a place where one can go to study coral reefs, mangrove vegetation and estuaries.

Answer Coral reefs-Andaman and Nicobar Islands. Mangrove vegetation-West Bengal. Estuaries-Coastal areas of Karnataka.

biodiversity and conservation notes

Question 1. Can you think of a scientific explanation, besides the analogy used by Paul Ehrlich, for the direct relationship between? diversity and stability of an ecosystem?

Answer Scientific explanation could be as follows:

Imagine a forest area, where diverse species of plants are growing. Plants harbour a variety of insects for which a lot of bird species would depend for their food. If a specific plant species die, the harbouring insect population will be affected which would lead to food unavailability for the birds. 

In addition, if the plant was a nitrogen fixer, the death of these plants would mean no replenishment of soil with nitrogen. This will affect the other plants as well. So if the cycle continues, the whole habitat/ ecosystem will be negatively affected.

Question 2. Though the conflict between humans and wildlife started with the evolution of man, the intensity of the conflict has increased due to the activities of modern man. Justify your answer with suitable examples.

Answer The first humans evolved around 2.5 million years ago. Agriculture began 11 thousand years ago leading to a huge increase in population size. It is since then that humans have started to exploit forest land for agriculture. A few centuries ago, development in medical technology increased the lifespan of humans and decreased the mortality rate of mother and child, further aggravating the problem of the human howe population. 

Along with this, the industrial revolution caused enormous consumption of Earth’s resources and gave back nothing but a monumental amount of waste destroying the natural habitat of other species, be it aquatic or terrestrial, endangering and later causing extinction thereof. This is how human activities have led to the increase in conflict between humans and wildlife.

Question 3. Species diversity decreases as we move away from the equator towards the poles. What could be the possible reasons? 

Answer Species diversity decreases as we move towards the poles, because

(i) Temperature decreases and conditions become harsh. 

(ii) Solar radiation, amount and intensity both decrease.

(iii) Vegetation decreases.

(iv) Fewer resources available to support species.nd Speciation is generally a function of time and environmental stability, so if conditions are too harsh, it is difficult for the species to survive and adapt. This results in a decrease in biodiversity towards the poles.

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