Important Questions for CBSE Class 12 Biology Chapter 13 - Biodiversity and Conservation 2024-25

Very Short Questions and Answers (1 Mark Questions)

1. Habitat loss and fragmentation have caused severe damage to a particular type of ecosystem. Name it. 

Ans: Habitat loss and fragmentation have caused severe damage to the tropical rainforest.

2. What trend is observed in respect of species diversity when we move from the equator to the poles? 

Ans:  When we move from the equator to 202the poles, generally the species diversity decreases. 

3. Which region is considered the one with the highest biodiversity on earth? What is the name given to such a region's forests? 

Ans: Amazonian rain forests are considered the region with the highest biodiversity on earth. They are also called the ‘Lungs of the planet’. 

4. Ecologists have discovered that the value of Z lies in the range of 0.1 to 0.2 regardless of taxonomic group or region. When will the slope of the line be steeper in a species-area relationship? 

Ans: Regardless of taxonomic group or region, the ecologists have discovered that the value of Z lies in the range of 0.1 to 0.2  the slope of a line is much steeper if one analyses the species-area relationship among very large areas such as entire continents. 

5. Define cryopreservation. Why is it useful in conserving biodiversity? 

Ans: Cryopreservation is preserving material in liquid nitrogen at -196^oC. It is useful in conserving biodiversity because it can be done to preserve threatened species in viable and fertile conditions for a long period. 

6. What is the reason for genetic variation shown by medicinal plant Rauwolfiavomitoria? 

Ans: Genetic variation might be in terms of potency and concentration of the active chemical reserpine produced by medicinal plants. 

7. Expand:

i) IUCN 

Ans: IUCN – International Union of Conservation of Nature and Natural Resources

ii) MAB  

Ans: MAB – Man and Biosphere program. 

8. What are hot spots? 

Ans: Hot spots are the priority areas of conservation that are extremely rich in species that have high endemism and are under constant threat of extinction. 

9. Name any two threatened animal species of India? 

Ans: Swamp Deer and Great Indian Rhinoceros are two threatened animal species of India.

10. Name the two most biodiversity-rich zones of India? 

Ans: The two most biodiversity-rich zones of India are The Western Ghats and the eastern Himalayas. 

11. Expand: 

i) WWF 

Ans: WWF – World wildlife fund 

ii) IBWL 

Ans: IBWL – Indian Board of wildlife. 

12. What is cryopreservation? 

Ans: Cryopreservation is a technique used in the storage of materials at an ultra-low temperature either by rapid cooling or by grade cooling and simultaneous dehydration at very low temp. 

13. Write the scientific name of the plant that yields reserpine? 

Ans: Rauwolfia Serpentina is the scientific name of the plant that yields reserpine.

14. Name any two conventional methods of ex-situ conservation? 

Ans: Botanical gardens and zoological parks are two conventional methods of ex-situ conservation. 

15. What do you mean by “vulnerable species”? 

Ans: Species that are believed to move into the category of endangered species shortly if the causal factors continue operating are called vulnerable species. 

16. Name the national park for Rhinoceros & lions in India respectively? 

Ans: The national park for Rhinoceros in Kaziranga National Park whereas the national park for lions is Gir National Park respectively. 

Short Answer Questions: (2 Marks) 

1. 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 in the year 2004 has described slightly more than 1.5 million species of plants and animals. According to Robert May, 7 million is the global species diversity. 

2. Explain co-extinction with a suitable example. 

Ans: Coextinction refers to the disappearance of a species with the extinction of another species of plant or animal with which it was associated in an obligatory way. e.g., Plant-pollinator mutualism. 

3. Study the pie diagram and answer the questions which follow: 

What do A, B, C, and D represent in these diagrams? 

Ans: In the given pie diagram 

A represents Crustaceans 

B represents Insects 

C represents Mosses and

D represents Fungi 

4. What is the IUCN red list? Give any two uses of this 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. The main uses of this list are as follows: 

i) It helps to identify and document the species with a high risk of extinction. 

ii) Also helps to provide awareness to the degree of threat to biodiversity. 

5.“Species diversity of plants is much less than that of animals” Why? 

Ans: The species diversity of plants is much less than that of animals because most animals possess nervous systems that control and coordinate various activities of animals. They also possess receptors to receive environmental stimuli; some of these responses are adaptive and ensure the survival of organisms in changing environmental conditions. 

6. What is the difference between in-situ and ex-situ conservation? 

Ans: The difference between in-situ and ex-situ conservation is as follows:

7.“The Amazonian rainforest in South America has the greatest biodiversity on earth”. Justify the statement. 

Ans: The greatest biodiversity on earth is found in the amazonian rainforest in South America. The Amazonian rainforest is the birthplace of about 40000 species of plants, 1,25,000 species of insects, 3000 species of fishes, 427 amphibians, 378 reptiles, 1300 birds, and 427 mammals. 

8. Sometimes the introduction of an exotic species upsets native species of the ecosystem. Substantiate the statement with the help of an example? 

Ans: The alien species become invasive and it will compete with the native species resulting in the extinction of indigenous species e.g. introduction of African catfish or clarias gariepinus for aquaculture purposes, which is also a posing threat to ours.

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

Ans: Species diversity refers to the various types of species present within a region. The two important measures of species diversity are:- 

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

ii) Species evenness:- It refers to the relative abundance with which each species is representing its presence in an area. 

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

Ans: Sacred groves are sacred forest patches around the places of worship. Tribal people are not allowed to cut even a single branch of a tree in these sacred grooves due to which many endemic species flourish in this region. 

11. What do you mean by IPR? What are the drawbacks of IPR? 

Ans: IPR refers to Intellectual property rights, under which transformed plants, animals or microorganisms can be patented and become exclusive private property. 

Drawbacks of IPR:- 

i) Increase in price of seeds 

ii) On agriculture the multinational companies will have greater domination. 

iii) Slower diffusion of new varieties 

iv) Replacement of local varieties with exotic varieties. 

12. Which type of conservation measures – in situ or ex-situ will help the larger number of species to survive? Explain. 

Ans: In-situ conservation will help the larger number of species to survive because it provides a natural environment for the growth and development of species. 

13. What is Biodiversity? Why has it become important recently? 

Ans: Biodiversity means the variability that exists among living organisms from all sources including interaliaterrestrial, marine, and other aquatic ecosystems ecological complexes of which, they are parts, this includes diversity within species, between species, and of the ecosystem. In modern times, industrialization, civilization, and urbanization has developed to large-scale use of different species of plants and animals as a result of which the life of several species of organisms has been endangered thus, Biodiversity has become so important in recent times. 

14. List the important attributes of a stable community? 

Ans: A stable community contains the following  important attributes :

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

ii) It must be either resistant or resilient to the disturbances occurring in season. 

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

15. Given below are the representations of the global diversity of invertebrates and vertebrates. 

Mention the class of organism which belongs to each group in this representation. 

Ans: The class of organism which belongs to  invertebrates and vertebrates group in the above representation is given below:

16. Give a reason why it is difficult to estimate global diversity for prokaryotes? 

Ans: To estimate the climate diversity of prokaryotes is very much difficult because-

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

ii) Under laboratory conditions many of these species cannot be cultured. 

iii) Their diversity would be put into millions with the help of techniques of biochemical & molecular biology. 

Long Questions and Answers (3 Marks Questions)  

1. Hotspots are regions of exceptionally high biodiversity. But they have become regions of accidental habitat loss too. Name the three hot spots of our country. Why are they called ‘Hot spots’? 

Ans: The hot spots of our country are The Western Ghats and Sri Lanka,  Indo-Burma, and Himalaya. They are called biodiversity hot spots as they show- 

(i) High level of species richness. 

(ii) High degree of endemism.

2. Study the diagram of the earth given below. Give the name of the pattern of biodiversity therein. Suggest any two reasons for this type of occurrence. 

Ans: The pattern of biodiversity shown in the given diagram of the earth is Latitudinal gradients. The two reasons behind the occurrence of Latitudinal gradients are:

(i) More solar energy available in the tropics results in more productivity. 

(ii) Tropical environments are less seasonal, so they are more predictable. 

3. What is so special about tropics that might account for their greater biological diversity? 

Ans: The specialty about tropics that might account for their greater biological diversity is as follows:

a) Speciation is a function of time, unlike temperate regions which are subjected to frequent glaciations in the past, tropical latitude has remained relatively undisturbed for millions of years and thus they had a long evolutionary time for species diversification. 

b) Tropical environments are less seasonal, more constant, and predictable too.

c) More solar energy is available in the tropical region is contributing to high productivity which is leading to greater diversity. 

4. What do you mean by biodiversity? What are the different types of Biodiversity? 

Ans: Biodiversity can be defined as the totality of genes of species and ecosystem of a given particular region. Three types of Biodiversities are:- 

i) Genetic Biodiversity:- It refers to the diversity of genes within a species. The greater the genetic diversity among organisms of a species greater will be the sustainability it has against environmental perturbations. Whereas genetically uniform populations are highly prone to diseases or harsh environments. 

ii) Species Biodiversity:- It refers to the variety of species within a region. It has two important measures:- 

a) Species richness:- means the number of species per unit area. 

b) Species evenness:- means abundance with which each species is represented in an area. 

iii) Ecosystem Biodiversity:- It refers to the variety of habitats, community types, and abiotic environment present in an area. It is again divided into three types:- 

a) Alpha Diversity - It refers to the number of species in a given community. 

b) Beta Diversity - Biodiversity which appears in the range of communities due to the replacement of species with change in the community is called beta diversity. 

c) Gamma Diversity - It refers to the diversity of habitats over the total geographical area. 

5. What do you mean by latitudinal gradient? What could be the possible reasons for diversity between tropic and temperate regions? 

Ans: The latitudinal gradient in diversity means that species diversity usually decreases as we move away from the equator towards the poles. The Tropic area of the latitudinal range 23.50c harbors more species than the temperate or polar area. To explain this difference three hypotheses have been proposed, these are:-

i) Speciation is a function of time, which temperate regions were subjected to frequent glaciations in the past, the tropics have to remain unchanged and hence evolved more species diversity. 

ii) As compared to the temperate region, tropical environments are less seasonal, relatively more constant, and predictable. Niche specialization and greater species diversity have been promoted by such constant environments. 

iii) There is more solar radiation available in the tropical region which contributes directly to greater productivity and indirectly to greater species diversity. 

6. Why is it necessary to conserve biodiversity? 

Ans: Following are the reasons for conserving biodiversity that can be grouped into three categories. 

i) Narrow Utilitarian Reasons:- Several economic benefits have been derived by human beings. These benefits are food, fiber, firewood, industrial products, and medicinal products. 

ii) Broad Utilitarian Reasons:- Biodiversity plays a major role in providing ecosystem services like:- 

a) production of oxygen 

b) Pollination of flowers, without which seeds or fruits are impossible to be produced. 

c) Aesthetic pleasures which involve bird watching, watching the flowers of the spring season, walking through thick forest, working up to bulbul’s song, etc. 

iii) Ethical Reasons:- Every species has their intrinsic value even if they are not of any value to us economically. We have a moral duty to care for their well-being and pass on the biological legacy in a proper form to our future generation. 

7. What is the relation between species richness and area? What is the significance of the slope of regression? 

Ans: Alexander Von Humboldt has observed that within a region, species richness increased with increase explored area but only upto a limit thus the relationship between species richness and area for several taxa is considered to be a rectangular hyperbola. On a log scale, the relationship becomes linear and is described law equation:

Log S = Log C + Z Log A

The values of the slope of regression are identical regardless of the taxonomic group or the region. When such analysis is done among the species belonging to very large areas, the slope of regression would be much steeper. 

8. What are the different approaches to biodiversity conservation in India? 

Ans: In India, there are two major approaches to the conservation of biodiversity. They are:- 

i) In-situ Conservation:- It is the process of protecting the endangered species of plant or animal in the natural habitat lay either protecting or cleaning up the habitat or by defending species from predators It includes:- 

a) Biosphere Reserves:- There are 425 biosphere reserves in the world of which 14 are in India. Hotspots have been identified for maximum protection to endemic or endangered species. 

b) National Park or Wildlife Sanctuaries:- India has about 90 national parks and 448 wildlife sanctuaries. 

c) Sacred Forests:- These are undisturbed forests without any human intervention and are surrounded by highly degraded landscapes. 

ii) Ex-situ Conservation:- It is the process by which the endangered species of plants or animals are given protection by removing them from threatened habitat and placing them under the care of humans. It includes:- 

a) Botanical garden, zoological park, and arboreta are conventional methods of ex-situ conservation 

b) Cryopreservation to the storage of materials at an ultra-low temperature either by rapid cooling or by gradual cooling and simultaneous dehydration at low temperature. 

9. Give an account of Biodiversity in India? 

• India is among the 10 mega-biodiversity countries in the world, thanks to the presence of diverse climatic conditions and ecological habitats, ranging from tropical, subtropical, and temperate zones.

• India is home to around 47,000 plant species and 81,000 animal species.

• Despite occupying only 2-4% of the world's land area, India contributes 10-35% of global biodiversity.

• India has a large number of native species, including 5,000 species of flowering plants belonging to 141 genera and 47 families that originated in India.

• India has a high level of endemism, with 62% of amphibian species and 50% of lizards being endemic to the country, with many found in the Western Ghats.

• India is the origin of 166 species of crop plants and 320 species of wild relatives of cultivated crops.

• India is rich in marine biodiversity, with a coastline of 7,500 km.

• India has two of the world's 25 biodiversity hotspots: the Western Ghats and the Eastern Himalayas.

10. What is the significance of Biodiversity to Human beings? 

Ans: Biodiversity provides numerous direct or indirect services to human beings. These are:

i) Source of food and improved varieties:- Biodiversity directly or indirectly add as the source of food, cloth, and shelter. 

ii) Fats and Oils:- A variety of plants are used to extract different kinds of oils. 

iii) Fibres:- A variety of plants eg. cotton, hemp, jute are the chief sources of fibers. 

iv) Resins:- Resins are sticky exudation of plants. 

v) Gums, Timber, Paper, Tannins, Dyes:- Plants species provide a variety of useful products such as gums, raisins, dyes, similarly animal species also provide leather, fur, honey, silk, pearl, etc. 

vi) Drugs and Medicines:- Living organisms also contain several therapeutically useful substances. 

vii) Stability of Ecosystem:- The food web, food chain energy flow in various trophic levels, and biochemical cycles occurs in natural ways without any hindrance if there is proper availability of diversified species 

viii) Aesthetic, Scientific and Recreational values:- Indian people grow many plants because they regard them as sacred. 

Very Long Questions and Answers (5 Marks Questions)

1. Why is the sobriquet ‘The Evil Quartet’ used in the context of biodiversity? Name the members of this quartet. Why do we grieve for the genes when a species is lost? 

Ans: The term ‘Evil Quartet’ is used to refer to the cause of the loss of biodiversity. The members of the quartet are:

(i) Habitat loss and fragmentation: When due to various human activities, large habitats are broken up into smaller fragments the animals requiring large territories such as elephants, birds, etc. are getting affected badly and their populations decline. 

(ii) Over-Exploitation: When the need for a resource becomes greed. e.g., overexploitation of passenger pigeons led to its extinction. Also marine fish are on the brink of being endangered due to overexploitation. 

(iii) Alien Species Invasion: Introduction of an intentional or unintentional species to a nearby area may disturb the harmony of existing species. e.g., Eichhornia after its introduction posed a big threat to the native species. 

(iv) Co-extinction: Extinction of one species invariably leads to the extinction of another when they are associated with each other in an obligatory way. E.g: When a host species becomes extinct, the obligate parasites that are dependent on it also die. 

We grieve for the genes when a species is lost because the wild forms are hardy and more resistant to pathogen attack and can be beneficial in crop breeding programs. 

2. Describe at least two approaches each for ex-situ conservation and in-situ conservation as a strategy for biodiversity conservation. 

Ans:  As a strategy for biodiversity conservation the two approaches for in-situ and ex-situ conservation is as follows: 

In situ conservation : 

(i) Identification and maximum protection should be provided to ‘hot spots.’

(ii) Legal protection to ecologically rich areas. 

(iii) Biosphere reserves, national parks, and sanctuaries. 

(iv) Sacred groves. 

Ex-situ Conservation : 

(i) Creation of zoological parks, botanical gardens, a wildlife sanctuary. 

(ii) Cryopreservation 

(iii) Seed bank. 

3. Mention the major causes for loss of biodiversity? 

Ans: The four major causes that are responsible for loss of biodiversity are:- 

i) Habitat loss and fragmentation of crops or conversion into grassland for raising beef cattle. Total loss of habitat deprives many plants and animals of their home and they face extinction. Similarly, when a large Habra becomes fragmented, then the animals requiring large territory and also those with migratory habits are getting affected adversely. 

ii) Overexploitation:- when nature is over-exploited by man for natural resources, many species become extinct. 

iii) Invasion of alien species:- The alien species become invasive and compete with native species and cause the extinction of indigenous species. 

iv) Co-extinction:- Co-extinction is a phenomenon in which when a species becomes extinct, the plant and animal species associated with it in an obligatory manner become extinct.

Important Related Links for CBSE Class 12 Biology